\documentclass[10pt]{article}

\usepackage{fullpage}
\usepackage{setspace}
\usepackage{parskip}
\usepackage{titlesec}
\usepackage[section]{placeins}
\usepackage{xcolor}
\usepackage{breakcites}
\usepackage{lineno}
\usepackage{hyphenat}





\PassOptionsToPackage{hyphens}{url}
\usepackage[colorlinks = true,
            linkcolor = blue,
            urlcolor  = blue,
            citecolor = blue,
            anchorcolor = blue]{hyperref}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{%
  \errmessage{\noexpand\@combinedblfloats could not be patched}%
}%
\makeatother


\usepackage{natbib}




\renewenvironment{abstract}
  {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize}
  {\bigskip}

\titlespacing{\section}{0pt}{*3}{*1}
\titlespacing{\subsection}{0pt}{*2}{*0.5}
\titlespacing{\subsubsection}{0pt}{*1.5}{0pt}


\usepackage{authblk}


\usepackage{graphicx}
\usepackage[space]{grffile}
\usepackage{latexsym}
\usepackage{textcomp}
\usepackage{longtable}
\usepackage{tabulary}
\usepackage{booktabs,array,multirow}
\usepackage{amsfonts,amsmath,amssymb}
\providecommand\citet{\cite}
\providecommand\citep{\cite}
\providecommand\citealt{\cite}
% You can conditionalize code for latexml or normal latex using this.
\newif\iflatexml\latexmlfalse
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}%

\AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}}

\usepackage[utf8]{inputenc}
\usepackage[ngerman,greek,english]{babel}



\usepackage{float}








\begin{document}

\title{Enhanced elimination of betamethasone in dichorionic twin pregnancies}



\author[1]{Grazielle Rodrigues}%
\author[2]{Jhohann Benzi}%
\author[1]{Luísa Matos}%
\author[1]{Stella Freitas}%
\author[2]{Maria Marques}%
\author[1]{Ricardo Cavalli}%
\author[1]{Elaine Moisés}%
\author[1]{Geraldo Duarte}%
\author[2]{Vera Lanchote}%
\author[1]{Alessandra Marcolin}%
\affil[1]{USP FMRP}%
\affil[2]{FCFRP-USP}%


\vspace{-1em}



  
  \date{May 16, 2024}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
Aims: No study has evaluated the BET pharmacokinetics in twin
pregnancies separated by chorionicity. The aim this study is to describe
and compare the BET pharmacokinetic parameters in singleton, dichorionic
(DC) and monochorionic (MC) twin pregnancies in the third trimester of
pregnancy. Methods: Twenty-six pregnant women received an intramuscular
dose of 6 mg of BET sodium phosphate plus 6 mg BET acetate. Serial blood
samples were collected for 24 hours after the first intramuscular BET
esters dose. BET plasma concentrations were quantified using a validated
HPLC analytical method. BET pharmacokinetic parameters were obtained
employing a non-compartment model, and were compared using ANOVA's test
with Tukey's multiple comparisons test. Correlations between clinical
features and pharmacokinetic parameters were analyzed using Pearson's
correlation. Preliminary data on the BET placental transfer were also
presented. Results: The geometric mean (IC 95\%) of AUC0-[?] 670.0
(504.3-805.2) vs 434.9 (311.2-539.6) ng.h/mL and the CL/F 18.38
(13.84-22.65) vs 29.40 (21.17-36.69) were significantly lower and
higher, respectively, in DC twin pregnancies compared to singleton.
Others pharmacokinetic parameters did not differ among the groups.
Conclusions: Data from this study suggest that the presence of two
fetoplacental units may increase the BET metabolism by CYP3A4 enzyme and
increase its elimination. Pharmacokinetic-pharmacodynamic clinical
studies are needed to investigate whether this BET pharmacokinetic
changes have clinical repercussions for the newborns and require dose
adjustment in DC twin pregnancies.%
\end{abstract}%



\sloppy


\textbf{Introduction}

Antenatal corticosteroids administration to pregnant women at imminent
risk of premature birth is strongly recommended in clinical practice
worldwide.\textsuperscript{1,2} It reduces the relative risks for
respiratory distress syndrome, intraventricular hemorrhage, necrotizing
enterocolitis, and systemic infections in the first 48 hours of life,
which are common causes of morbidity and mortality in preterm
newborns.\textsuperscript{3} Current data demonstrate that
corticosteroids administration is most beneficial within one week of
therapy. Based on the scientific evidence, the World Health
Organization, the American College of Obstetricians and Gynecologists,
the Royal College of Obstetricians and Gynaecologists, and the Society
of Obstetricians and Gynaecologists of Canada, all recommend antenatal
corticosteroids administration to women at risk for preterm delivery
between 24--34 weeks of gestation.\textsuperscript{4--7}

Preterm birth is the most common perinatal morbidity associated with
twin pregnancies, present in 30 to 50\% of cases regardless of
chorionicity.\textsuperscript{8,9} Therefore, the current guidelines
also recommend administration of antenatal corticosteroids to women with
multiple pregnancy and threatened preterm delivery. However, it is
uncertain whether the benefits of antenatal corticosteroids observed in
singleton pregnancies are similar in twin pregnancies because of the
small number of twin pregnancies included in the
studies.\textsuperscript{10,11} Also, the efficacy of corticosteroids in
promoting lung maturation in twins may be reduced because of the more
remarkable maternal physiological changes in multiple pregnancies. These
changes could affect the pharmacokinetics of many drugs, including
half-life, volume of distribution, and clearance in singleton pregnancy
differently from that in twin
pregnancy.\textsuperscript{12--14}Consequently, that efficacy of
corticosteroids in inducing maturation could be reduced due to the lower
plasma exposure of twin fetuses to these drugs.

Betamethasone (BET) has been more commonly used in studies evaluating
the effect of antenatal corticosteroid therapy on neonatal outcomes. BET
is formulated as a fast releasing BET phosphate ester prodrug or a
dual-acting formulation containing BET phosphate plus BET acetate
esters. Both esters are fast and extensively metabolized to the active
glucocorticoid BET.\textsuperscript{15,16} As far as we know, there are
no bioavailability data after intramuscular BET esters administration.
Ke and Milad (2019) have assumed that 94\% of BET elimination is
dependent on CYP3A4 based on the BET renal clearance in healthy adults
of approximately 0.49 L/ h.\textsuperscript{17} Considering that CYP3A
is induced by 86-124\% in late pregnancy compared to postpartum
period,\textsuperscript{18} BET total clearance is probably enhanced in
pregnancy according to studies in healthy adults and pregnant
women.\textsuperscript{19--22,11,15,23} BET total clearance has also
been reported to be increased in twin pregnancies compared to singleton
ones.\textsuperscript{19} Although there are studies that have evaluated
the BET pharmacokinetics in twin pregnancies, they are few, and none of
them studied multiple pregnancies separated by chorionicity.

Therefore, the objectives of the present study were to describe and
compare the BET pharmacokinetic parameters in singleton, dichorionic
(DC) and monochorionic (MC) twin pregnancies in order to evaluate, in
the future trials, the need for adjusted doses of BET according to the
chorionicity of multiple pregnancies.

\textbf{Methods}

\textbf{Patients} A cross-sectional pharmacokinetic study of singleton
and twin pregnancies was performed, including pregnant women underwent
tocolysis in the local hospital because of preterm labour from August
2018 to September 2019. This study was approved by the local Ethics
Research Committee (protocol number 8676/2017) of University Hospital of
the Ribeir\selectlanguage{ngerman}ão Preto Medical School (São Paulo, Brazil), and patients gave
signed informed consent. The study protocol was registered on the
Brazilian Registry of Clinical Trials (ReBEC,
www.ensaiosclinicos.gov.br) under ID number RBR-2v2mwkz. Participation
in the study was limited to the inpatient population to ensure
compliance with serial blood sampling. Thirty-five pregnant women,
between 24 and 34 weeks of gestation, and \textgreater{}18 years old
were clinically eligible for the antenatal corticosteroid treatment and
were approached for enrollment. The following exclusion criteria were
applied: use of tobacco, alcohol or illegal substances; maternal
diseases with vasculopathy identified by laboratory tests or signals of
placental insufficiency; the use of drugs that interact with BET; or
maternal desire to withdraw. Finally, the data from 26 pregnant women,
divided into three groups (9 singleton pregnancies, 9 DC and 8 MC twin
pregnancies) were analyzed.

\textbf{Clinical protocol}

A maternal blood sample (5 mL) was obtained from each patient before
administering the first dose of BET esters to assess biochemical, renal,
hepatic, metabolic and haematological parameters. Laboratory tests were
carried out to assess the functional normality of the organ systems. All
pregnant women received a standard regimen of BET esters intramuscularly
(Celestone Soluspan®, Mantecorp, Anápolis, GO, Brazil -- equal amounts
of BET sodium phosphate and BET acetate at a dose of 12 mg every, two
times 24h apart). Serial blood samples (5 mL) were collected immediately
before and 5, 10, 15, 35 minutes and 1, 3, 6, 8, 10, 16 and 24 hours
after the first intramuscular BET esters dose to determine BET plasma
concentrations. In some cases, there was a failure to stop labour and
delivery occurred (n=5). Simultaneous samplings of maternal blood,
umbilical cord (for each fetus if twin pregnancy), and intervillous
space (the space near the umbilical cord insertion if twin pregnancy)
were performed to assess the placental transfer and distribution of BET
in these compartments. Blood was collected from the umbilical cord after
the cord was clamped and sectioned and the placenta expelled through the
birth canal, with no risk for the mother or neonate. The technique
described by Camelo Júnior et al. was adopted to collect blood samples
from the umbilical vein and the intervillous space.\textsuperscript{24}

All blood samples for BET pharmacokinetics and transplacental transfer
studies were transferred to heparinized tubes protected from light and
containing 10 \selectlanguage{greek}µ\selectlanguage{english}L of stabilizing solution of 2 M of sodium arsenate
dibasic heptahydrate. The blood samples were then centrifuged within a
maximum period of 15 minutes at 21.500 [?] \selectlanguage{english}g for 5 minutes at 4\selectlanguage{ngerman}°C. The
plasma was separated and transferred to cryogenic tubes containing 10 \selectlanguage{greek}µ\selectlanguage{english}L
of a stabilizing solution of potassium fluoride 50\% and were stored at
-70\selectlanguage{ngerman}°C until analysis.\textsuperscript{25,16}

\textbf{Betamethasone assay and analytical validation}

BET determination in plasma was performed by an LC-MS/MS system
according to a method previously validated by the research group
(unpublished data -- Rodrigues et al., manuscript accepted by The
Brazilian Journal of Pharmaceutical Sciences). Briefly, 500 \selectlanguage{greek}µ\selectlanguage{english}L of plasma
were added to an internal standard solution (IS; deuterated
betamethasone-acetate; 1 \selectlanguage{greek}µ\selectlanguage{english}g/mL in methanol) and submitted to the
extraction process with 6 mL of diisopropyl ether.

Analytes were separated in a LiChrospher reversed-phase C-8 column with
a LiChrospher\selectlanguage{ngerman}® 100 RP-8 C-8 guard column, using a mixture of methanol
and ammonium formate 0.05 mM (90:10 v/v) as a mobile
phase.\textsuperscript{25,16} The MS/MS detection system was a Quattro
Micro LC triple quadrupole (Micromass, Manchester, United Kingdom)
equipped with an electrospray interface (ESI) operating in positive ion
mode. The method revealed linearity in the range of 2-250 ng/mL plasma
for BET. Coefficients of variation and inaccuracy percentage were \selectlanguage{english}[?]15\%,
indicating that the method was precise and accurate. Moreover, the
method showed selectivity and did not presented matrix or carry-over
effects. Stability tests also presented the coefficient of variation and
relative standard errors \selectlanguage{english}[?] 15\%. Therefore, the method for BET
pharmacokinetics studies had adequate confidence limits, ensuring the
results' reproducibility and repeatability.

\textbf{Pharmacokinetic analysis}

The BET pharmacokinetics was calculated based on the plasma
concentration versus time using
Phoenix\selectlanguage{english}\textsuperscript{}WinNonLin\selectlanguage{english}\textsuperscript{} software, version
6.3 (Certara, Princeton, New Jersey, USA), employing a noncompartmental
analysis. Maximum plasma concentration (Cmax) and time to reach Cmax
(Tmax) were obtained from data of the individual patients. Areas under
the plasma concentration-time curves were calculated by the trapezoidal
rule and extrapolated to the infinity. Apparent total clearance (CL/F)
was evaluated by the equation CL/F =
Dose/AUC\selectlanguage{english}\textsuperscript{0-\textbf{[?]}} and apparent volume of
distribution (Vd/F) was calculated by the equation of the software. The
BET placental transfer was evaluated by the umbilical cord to maternal
vein concentration ratio and intervillous space to maternal vein
concentration ratio.

\textbf{Statistical analysis}

Data was analyzed by GraphPad Prism software\selectlanguage{english}\textsuperscript{} (CA,
USA). The BET pharmacokinetics data are presented as median and
interquartile range. Pharmacokinetic parameters presented a normal
distribution (Shapiro-Wilk test; p-value\textless{}0.05) so they were
compared using ANOVA's test with Tukey's multiple comparisons test
(p-value\textless{}0.05).\textsuperscript{26,27} Correlations between
clinical features and pharmacokinetic parameters were analyzed using
Pearson's correlation (p-value \textless{}0.05).

\textbf{Results}

The 26 pregnant women were divided into three groups: singleton
pregnancies (n=9), DC twin pregnancies (n=9) and MC twin pregnancies
(n=8). The groups of pregnant women were compared regarding maternal
age, body mass index and gestational age at childbirth. There were no
significant differences among these features for the three groups. The
demographic and laboratory test results of the pregnant women are
presented in Table 1. Serum albumin concentration was significantly
higher in MC twin pregnancies compared to singleton and DC twin
pregnancies. On the other hand, the plasmatic urea concentration was
significantly lower in MC twin pregnancies.

The median curves of plasma BET concentration versus time for the three
groups were determined during the 24h after a single intramuscular dose
of 12mg of BET sodium phosphate and BET acetate (Figure 1). Table 2
lists the pharmacokinetic parameters, demonstrating differences among
the groups of pregnant women. The AUC\selectlanguage{english}\textsuperscript{0-[?]} and CL/F were
significantly lower and higher, respectively, in DC twin pregnancies
compared to singleton and MC twin pregnancies. On the other hand, Cmax,
Tmax and Vd/F were not significatively different among the groups. Vd/F
(p=0.02; r=0.4530) was correlated to body mass index, but not to any
other demographic or biochemical data (Figure 2).

Figure 3 shows preliminary data on the BET placental transfer, expressed
by the umbilical cord to maternal vein concentration ratio and
intervillous space to maternal vein concentration ratio.

\textbf{Discussion}

The present study demonstrated significant differences in the BET
pharmacokinetics in DC twin pregnancies. The AUC\selectlanguage{english}\textsuperscript{0-[?]}and
CL/F were significantly lower and higher, respectively, in DC twin
pregnancies compared to singleton and MC twin pregnancies while there
were no differences in the other pharmacokinetic parameters. The
understanding of the pharmacokinetics of drugs during pregnancy is
crucial for the development of appropriate dosage regimens. The clinical
BET pharmacokinetics have been investigated in healthy
adults,\textsuperscript{20,21,23} as well as in pregnant
women.\textsuperscript{19,22,11,15}

Previous studies developed BET population pharmacokinetic
models\textsuperscript{19,22} or classical pharmacokinetic
approaches\textsuperscript{20,21} in both singleton and twin
pregnancies. However, none of these studies evaluated the BET
pharmacokinetics or BET placental transfer in twin pregnancies
discriminated by chorionicity. This study is unprecedented regarding the
BET pharmacokinetic studies in singleton, DC and MC twin pregnancies.

Many demographic and clinical variables such as body composition, blood
volume, hormonal levels, hepatic and placenta metabolism could interfere
with BET pharmacokinetics and explain the findings of the present
study.\textsuperscript{28,29,11} Furthermore, the influence of the
maternal physiological changes on the kinetics disposition of drugs is
more remarkable in the third trimester of pregnancy and multiple
pregnancies.\textsuperscript{28--30} It is worth mentioning that all
pregnant women included in this clinical trial were in the last
trimester of their pregnancies.

Few studies that investigated BET elimination in unchanged form in urine
evidenced that the contribution of renal clearance in total clearance is
not significant, supposing that BET is eliminated mainly by its
metabolism.\textsuperscript{17,23,31} Although pathways that mediate the
BET hepatic metabolism have not been fully established, some studies
have proposed a primary and fundamental role for the cytochrome P450
enzymes, mainly CYP3A4.\textsuperscript{17,32} Even though some authors
have suggested that BET placental metabolism seems to be low or
negligible,\textsuperscript{33} others have highlighted the possibility
of increased metabolism due to two or more fetoplacental units in twin
pregnancies.\textsuperscript{11}

Data on the impact of twin pregnancies on BET pharmacokinetics appear to
be contradictory to date. Our data show BET
AUC\selectlanguage{english}\textsuperscript{0-[?]}lower in DC twin pregnancies than in singleton
and MC twin pregnancies. The presence of two fetoplacental units in DC
twin pregnancies could result in a higher metabolism mediated by CYP3A
enzymes. Besides, potentially higher hormone levels in DC pregnancy
could induce CYP3A enzymes in both the placenta and maternal liver and
explain these changes. Also, the increased hepatic flow during pregnancy
could rise the BET clearance and reduce the AUC.

Although some studies have shown significant differences in CL/F or
t\textsubscript{1/2} between singleton and twin
pregnancies,\textsuperscript{19,11} other research groups have not found
similar results.\textsuperscript{22} Foissac and collaborators found a
28\% increase in BET CL/F in twin pregnancies without chorionicity
discrimination compared to singleton pregnancies.\textsuperscript{19} In
the present study, the BET CL/F values did not differ between MC twin
and singleton pregnancies, but DC twin pregnancies presented a 40\%
increase in this pharmacokinetics parameter compared other pregnancies.
Enhanced hepatic metabolism can also explain the pregnancy-related
increase in CL/F.

Our study showed a positive correlation between maternal body mass index
and BET Vd/F. This finding is similar to the Della Torre et al. study,
which showed that maternal lean body weight was a covariate for the Vd/F
using a population pharmacokinetic model.\textsuperscript{22} Also, the
magnitude of the values of the dose-independent parameters such as CL/F
and Vd/F in the present study were similar to those of previous studies
conducted with pregnant women (Table
2).\textsuperscript{19,22,11}Betamethasone is a lipophilic drug and can
bind significantly to tissue.\textsuperscript{34} The significant change
in pregnant women's body size with twin fetuses provides one more
possible explanation for the lower AUC in these pregnancies than
singleton ones.

Our study has some strengths. First, few studies have analyzed BET
pharmacokinetics in twin pregnancies, and no study to date has analyzed
BET pharmacokinetic parameters in twin pregnancies separated by
chorionicity. Second, there was only one researcher conducting the
clinical protocol. This ensured the correct interval between the BET
administration and the first blood sample and the serial blood sampling
intervals. Third, before BET pharmacokinetic analysis in the present
study, a BET assay and analytical validation were performed, and the
method showed suitable sensibility, linearity, accuracy and precision
for pharmacokinetics and placental transfer studies in a twin pregnancy.

Our study was not without limitations. Preliminary data on BET placental
transfer can be considered limited mainly due to the low number of
patients in each group and different intervals between drug
administration and delivery. On the other hand, a previous study showed
that BET concentration in cord blood decreases within
days.\textsuperscript{35} The analysis of umbilical vein/maternal vein
and intervillous space/maternal vein ratios showed that BET
concentration in intervillous space is higher than the fetal
compartments. The inclusion of a more significant number of pregnant
women and applying a protocol with greater precision in the intervals
between the BET administration and the collection of maternal and fetal
blood samples are being carried out to confirm this finding.

In conclusion, this study shows the influence of twin pregnancies on BET
pharmacokinetics, suggesting that the presence of two fetoplacental
units may increase the drug's metabolism by CYP3A4 enzyme and increase
its elimination. Pharmacokinetic-pharmacodynamic clinical studies are
needed to investigate whether this BET pharmacokinetic changes have
clinical repercussions for the newborns and require dose adjustment in
DC twin pregnancies.

\textbf{Data availability} : The data that support the findings of this
study are available on request from the corresponding author.

\textbf{Funding statement:} The authors thank the Sao Paulo Research
Foundation (FAPESP) {[}grant 2017/19256-6{]} and in part by the Higher
Education Improvement Coordination - Brazil (CAPES) {[}Finance Code
001{]}.

\textbf{Authorship statement:} G.F.P.R. and A.C.M. designed the clinical
study and wrote the manuscript; G.F.P.R., L.H.C.M. and S.F.F. performed
blood sample collections; G.F.P.R., M.P.P. and V.L.L. performed the BET
quantification in plasma. J.R.L.B and L.V.L. performed the
pharmacokinetic ans statiscal analysis. G.F.P.R., R.C., E.C.D.M., G.D.,
A.C.M, J.R.L.B and L.V.L. performed manuscript review.

\textbf{Conflict of interest disclosure} : The authors have no conflicts
of interest to declare.

\textbf{Ethics approval statement:} Protocol number 8676/2017, of
University Hospital of the Ribeirao Preto Medical School (Sao Paulo,
Brazil).

\textbf{Clinical trial registration:} The study protocol was registered
on the Brazilian Registry of Clinical Trials (ReBEC,
www.ensaiosclinicos.gov.br) under ID number RBR-2v2mwkz.

\textbf{ORCID:}

Grazielle de Fatima Pinto Rodrigues: 0000-0003-4883-1332

Jhohann Richard de Lima Benzi: 0000-0001-6986-6193

\textbf{References}

1. Gilstrap LC, Christensen R, Clewell WH, et al. Effect of
Corticosteroids for Fetal Maturation on Perinatal Outcomes: NIH
Consensus Development Panel on the Effect of Corticosteroids for Fetal
Maturation on Perinatal Outcomes. JAMA. 1995;273(5):413-418.

2. Roberts D, Dalziel S. Antenatal corticosteroids for accelerating
fetal lung maturation for women at risk of preterm birth. Cochrane
Database Syst Rev. 2006;(3):CD004454.

3. Roberts D, Brown J, Medley N, Dalziel SR. Antenatal corticosteroids
for accelerating fetal lung maturation for women at risk of preterm
birth. Cochrane Database Syst Rev. 2017;3:CD004454.

4. Skoll A, Boutin A, Bujold E, et al. No. 364-Antenatal Corticosteroid
Therapy for Improving Neonatal Outcomes. J Obstet Gynaecol Can.
2018;40(9):1219-1239.

5. ACOG. American College of Obstetricians and Gynecologists' Committee
on Practice Bulletins---Obstetrics. Practice Bulletin No. 171:
Management of Preterm Labor. Obstet Gynecol. 2016;128(4):e155-164.

6. WHO. World Health Organization. Recommendations on Interventions to
Improve Preterm Birth Outcomes.; 2015.

7. National Institute for Health and Care Excellence. Preterm Labour and
Birth. NICE Guideline NG25.; 2015.

8. Marleen S, Hettiarachchi J, Dandeniya R, et al. Maternal clinical
predictors of preterm birth in twin pregnancies: A systematic review
involving 2,930,958 twin pregnancies. European Journal of Obstetrics \&
Gynecology and Reproductive Biology. 2018;230:159-171.

9. Lee YM. Delivery of Twins. Seminars in Perinatology.
2012;36(3):195-200.

10. Magann EF, Haram K, Ounpraseuth S, Mortensen JH, Spencer HJ,
Morrison JC. Use of antenatal corticosteroids in special circumstances:
a comprehensive review. Acta Obstet Gynecol Scand. 2017;96(4):395-409.

11. Ballabh P, Lo ES, Kumari J, et al. Pharmacokinetics of betamethasone
in twin and singleton pregnancy. Clin Pharmacol Ther. 2002;71(1):39-45.

12. Koren G, Pariente G. Pregnancy- Associated Changes in
Pharmacokinetics and their Clinical Implications. Pharm Res.
2018;35(3):61.

13. Ansari J, Carvalho B, Shafer SL, Flood P. Pharmacokinetics and
Pharmacodynamics of Drugs Commonly Used in Pregnancy and Parturition.
Anesth Analg. 2016;122(3):786-804.

14. Tan EK, Tan EL. Alterations in physiology and anatomy during
pregnancy. Best Practice \& Research Clinical Obstetrics \& Gynaecology.
2013;27(6):791-802.

15. Petersen MC, Ashley JJ, McBride WG, Nation RL. Disposition of
betamethasone in parturient women after intramuscular administration. Br
J Clin Pharmacol. 1984;18(3):383-392.

16. Petersen MC, Nation RL, Ashley JJ. Simultaneous determination of
betamethasone, betamethasone acetate and hydrocortisone in biological
fluids using high-performance liquid chromatography. J Chromatogr.
1980;183(2):131-139.

17. Ke AB, Milad MA. Evaluation of Maternal Drug Exposure Following the
Administration of Antenatal Corticosteroids During Late Pregnancy Using
Physiologically-Based Pharmacokinetic Modeling. Clin Pharmacol Ther.
2019;106(1):164-173.

18. Hebert MF, Easterling TR, Kirby B, et al. Effects of pregnancy on
CYP3A and P-glycoprotein activities as measured by disposition of
midazolam and digoxin: a University of Washington specialized center of
research study. Clin Pharmacol Ther. 2008;84(2):248-253.

19. Foissac F, Zheng Y, Hirt D, et al. Maternal betamethasone for
prevention of Respiratory Distress Syndrome in neonates: population
pharmacokinetic and pharmacodynamic approach. Clinical Pharmacology \&
Therapeutics. 2020;n/a(n/a).

20. Jobe AH, Milad MA, Peppard T, Jusko WJ. Pharmacokinetics and
Pharmacodynamics of Intramuscular and Oral Betamethasone and
Dexamethasone in Reproductive Age Women in India. Clin Transl Sci.
2020;13(2):391-399.

21. Salem I I, Najib N. Pharmacokinetics of betamethasone after
single-dose intramuscular administration of betamethasone phosphate and
betamethasone acetate to healthy subjects. Clinical Therapeutics.
2012;34(1).

22. Della Torre M, Hibbard JU, Jeong H, Fischer JH. Betamethasone in
pregnancy: influence of maternal body weight and multiple gestation on
pharmacokinetics. American Journal of Obstetrics and Gynecology.
2010;203(3):254.e1-254.e12.

23. Petersen MC, Nation RL, McBride WG, Ashley JJ, Moore RG.
Pharmacokinetics of betamethasone in healthy adults after intravenous
administration. Eur J Clin Pharmacol. 1983;25(5):643-650.

24. Camelo Junior JS, Martinez FE, Jorge SM, de Sala MM. A new method
for sampling maternal blood in the placental intervillous space. Fetal
Diagn Ther. 1995;10(5):322-325.

25. Salem I I, Alkhatib M, Najib N. LC--MS/MS determination of
betamethasone and its phosphate and acetate esters in human plasma after
sample stabilization. Journal of Pharmaceutical and Biomedical Analysis.
2011;56(1):983-991.

26. Patricio M, Ferreira F, Oliveiros B, Caramelo F. Comparing the
performance of normality tests with ROC analysis and confidence
intervals. Communications in Statistics - Simulation and Computation.
2017;46(10):7535-7551.

27. Clinical Pharmacology and Therapeutics. Statistical guide for
clinical pharmacology \& therapeutics. Clin Pharmacol Ther.
2010;88(2):150-152.

28. Tasnif Y, Morado J, Hebert MF. Pregnancy-related pharmacokinetic
changes. Clin Pharmacol Ther. 2016;100(1):53-62.

29. Costantine MM. Physiologic and pharmacokinetic changes in pregnancy.
Front Pharmacol. 2014;5:65.

30. Tracy TS, Venkataramanan R, Glover DD, Caritis SN, National
Institute for Child Health and Human Development Network of
Maternal-Fetal-Medicine Units. Temporal changes in drug metabolism
(CYP1A2, CYP2D6 and CYP3A Activity) during pregnancy. Am J Obstet
Gynecol. 2005;192(2):633-639.

31. Murphy D, West HF, Bethel AM. SOME ASPECTS OF THE METABOLISM AND
DISPOSITION OF BETAMETHASONE. Acta Endocrinol (Copenh). 1964;45:498-508.

32. McCrea JB, Majumdar AK, Goldberg MR, et al. Effects of the
neurokinin1 receptor antagonist aprepitant on the pharmacokinetics of
dexamethasone and methylprednisolone. Clinical Pharmacology \&
Therapeutics. 2003;74(1):17-24.

33. Blanford AT, Murphy BE. In vitro metabolism of prednisolone,
dexamethasone, betamethasone, and cortisol by the human placenta. Am J
Obstet Gynecol. 1977;127(3):264-267.

34. Green B, Duffull SB. What is the best size descriptor to use for
pharmacokinetic studies in the obese? British Journal of Clinical
Pharmacology. 2004;58(2):119.

35. Gyamfi C, Mele L, Wapner RJ, et al. The effect of plurality and
obesity on betamethasone concentrations in women at risk for preterm
delivery. Am J Obstet Gynecol. 2010;203(3):219.e1-5.

\par\null

\textbf{Table 1} -- Demographic, clinical and laboratory data from
singleton and twin pregnancies.\selectlanguage{english}
\begin{longtable}[]{@{}lllll@{}}
\toprule
\begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
Variables (Reference value)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
Singleton (n=9)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
MC twin (n=8)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
DC twin (n=9)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
\emph{p} value*\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Age (years)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
27 (21 -- 31)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
29 (25 -- 33)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
26 (22 -- 30)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.5199\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Body mass index (kg/m\textsuperscript{2})\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
26.82 (22.97 -- 30.39)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
29.10 (25.13 -- 32.93)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
27.64 (23.61 -- 31.39)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.6403\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Gestational age (days)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
209 (193 -- 225)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
216 (207 -- 225)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
200 (180 -- 219)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.2773\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Glycemia (mg/dL) (70 -- 100)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
84 (61 -- 104)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
80 (68 -- 92)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
88 (60 -- 112)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.8488\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\selectlanguage{greek}α\selectlanguage{english}1-AGP (mg/dL) (50 -- 120)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
60.40 (54.17 -- 66.36)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
65.22 (52.76 -- 76.94)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
64.59 (46.15- 80.66)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.8390\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Albumin (g/dL) (3.5 -- 4.8)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
3.54 (3.47 -- 3.61)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
3.69 (3.45 -- 3.93)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
3.41 (3.28 -- 3.55)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\textbf{0.0222}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Total proteins (g/dL) (6 -- 8.5)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
6.23 (6.01 -- 6.44)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
6.04 (5.62 -- 6.47)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
5.81 (5.42 -- 6.18)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.1203\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Total bilirubin (mg/dL) (0.2 -- 1.2)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.40 (0.22 -- 0.56)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.33 (0.21 -- 0.44)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.82 (0.22 -- 0.95)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.3860\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Alkaline phosphatase (U/L) (65 -- 300)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
245 (168 -- 316)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
353 (289 -- 414)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
278 (181 -- 366)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.0960\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Gamma-GT (U/L) (11 -- 50)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
9.6 (7.2 -- 12)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
22 (12 -- 30)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
18 (9.8 -- 26)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.0734\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
AST (U/L) (\emph{\textless{}} 32)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
15.88 (12.05 -- 19.25)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
20.41 (10.89 -- 28.27)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
19.57 (15.81 -- 22.87)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.4880\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
ALT (U/L) (\emph{\textless{}} 31)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
12.06 (9.27 -- 14.48)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
18.17 (5.58 -- 25.30)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
18.01 (8.58 -- 25.93)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.5781\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Creatinine clearance (75-129 mL/min/1.73)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
203 (155 -- 245)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
213 (178 -- 247)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
203 (191 -- 215)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.8891\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Creatinine (mg/dL) (0.7 -- 1.5)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.56 (0.48 -- 0.64)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.55 (0.45- 0.65)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.58 (0.49 -- 0.65)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.8662\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Urea (mg/dL) (10 -- 50)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
13.43 (9.21 -- 17.13)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
11.41 (7.88 -- 14.76)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
17.31 (13.79 -- 20.49)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\textbf{0.0327}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Cholesterol (mg/dL) (\textless{} 200)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
212 (188 -- 235)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
255 (212 -- 296)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
241 (188 -- 291)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.1500\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Triglycerides (mg/dL) (\textless{} 150)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
153.1 (86.87 -- 205.1)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
203.8 (114.2 -- 286.2)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
236.7 (175.6 -- 293.2)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.166\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Hemoglobin (g/dL) (11,0 -- 15,5)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
12 (11 -- 13)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
12 (11 -- 13)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
12 (11 -- 12)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.620\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

Values are expressed as geometric mean (95\% confidence interval). DC:
dichorionic; MC: monochorionic; n: number of subjects; \selectlanguage{greek}α\selectlanguage{english}1-AGP: \selectlanguage{greek}α\selectlanguage{english}1-acid
glycoprotein; Gama-GT: gamma-glutamyl transpeptidase; AST: aspartate
aminotransferase; ALT: alanine transaminase. *ANOVA's test with Tukey's
multiple comparisons test (p-value \textless{} 0.05).

\par\null

\textbf{Table 2 --} Betamethasone (BET) pharmacokinetic parameters and
placental transfer in singleton, monochorionic and dichorionic twin
pregnancies after a single intramuscular dose of 6 mg of betamethasone
acetate plus 6 mg betamethasone phosphate.\selectlanguage{english}
\begin{longtable}[]{@{}lllll@{}}
\toprule
\begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
BET pharmacokinetic parameter\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
Singleton pregnancies (n=9)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
MC twin pregnancies (n=8)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
DC twin pregnancies (n=9)\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
\emph{p}-value\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
C\textsubscript{max} (ng/mL)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
55.35 (36.48- 70.96)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
52.34 (40.07 -- 63.61)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
44.87 (29.44 -- 56.82)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.5299\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
t\textsubscript{max} (h)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
2.06 (1.03 -- 2.90)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
1,5 (0.86 -- 2.01)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
1.80 (0.83 -- 2.52)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.5665\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
AUC\textsuperscript{0-[?]} (ng.h/mL)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
670.0 (504.3 -- 825.2)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
494.9 (355.4 -- 624.1)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
434.9 (311.2 -539.6)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\textbf{0.0345}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
CL/F (L/h)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
18.38 (13.84 -- 22.65)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
25.46 (18.30 -- 32.13)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
29.4 (21.17 -- 36.69)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\textbf{0.0324}\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Vd/F (L)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
226.1 (112.7 -- 316.9)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
265.4 (172.0 -- 353.6)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
279.9 (159.6 -- 389.6)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.6746\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
BET transplacental transfer\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\textbf{Singleton pregnancies} \textbf{(n=1)}\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\textbf{MC twin} \textbf{(n=1)}\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\textbf{DC twin} \textbf{(n=6\textsuperscript{a})}\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Drug administration and delivery interval (h)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
20.34\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
6.04\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
2.02 (1.53 -- 2.62)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Umbilical vein/Maternal vein ratio\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.33\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.20\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.15 (0.09 -- 0.25)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
Intervillous space /Maternal vein ratio\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.54\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.31\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
0.22 (0.07 -- 0.60)\strut
\end{minipage} & \begin{minipage}[t]{0.19\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

Values are expressed as geometric mean (95\% confidence interval). BET:
betamethasone; DC: dichorionic; MC: monochorionic; n: number of
subjects; C\textsubscript{max}: maximum plasma concentration;
t\textsubscript{max}: time to reach C\textsubscript{max};
AUC\textsuperscript{0-[?]}: area under the plasma concentration vs time
curve extrapolated to infinity; CL/F: apparent clearance; Vd/F: apparent
volume of distribution. *ANOVA's test with Tukey's multiple comparisons
test (p-value \textless{} 0.05).\textsuperscript{a} Both twins were
included, thus, 6 samples of umbilical vein and intervillous space were
collected.

\textbf{Figures legends:}

\textbf{Figure 1} -- Plasma concentration versus time of betamethasone
in singleton pregnancies (n=9; circles), monochorionic (MC) twin
pregnancies (n=8; squares) and dichorionic (DC) twin pregnancies (n=9;
triangles) after a single dose of 6mg of betamethasone acetate plus 6mg
betamethasone phosphate. Values are expressed as geometric mean (95\%
confidence interval).

\textbf{Figure 2} -- Correlation between betamethasone apparent volume
of distribution (Vd/F) and body mass index (BMI) (p=0.02; r=0.4530).
Data are presented individually. Singleton pregnancies (n=8) are
represented as full circles, monochorionic (MC) twin pregnancies (n=9)
are represented as open circles and dichorionic (DC) twin pregnancies
(n=9) are represented as grey circles.

\textbf{Figure 3} -- Betamethasone concentration in the transplacental
transfer. Singleton pregnancies (n=1) are represented as circles,
monochorionic (MC) twin pregnancies (n=1) are represented as squares and
dichorionic (DC) twin pregnancies (n=3) are represented as hexagons.
Values are expressed as individual data. Symbols with a dot inside
represent maternal vein concentrations; Symbols with an ``x'' inside
represent intervillous space concentrations; Semi-full symbols represent
umbilical vein concentrations; Open symbols represent intervillous space
to maternal vein ratios, and solid symbols represent umbilical vein to
maternal vein ratios.

\selectlanguage{english}
\FloatBarrier
\end{document}

