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\begin{document}

\title{Outcomes following the detection of fetal oedema in early pregnancy
prior to non-invasive prenatal testing: a retrospective cohort study}



\author[1]{Jayshree Ramkrishna}%
\author[1]{Melody Menezes}%
\author[1]{Kedar Humnabadkar}%
\author[1]{Cheryl Tse}%
\author[1]{Maria Maxfield}%
\author[2]{Fabrício  Da Silva Costa}%
\author[3]{Daniel Rolnik}%
\author[1]{Simon Meagher}%
\affil[1]{Monash IVF Group}%
\affil[2]{Monash University Faculty of Medicine Nursing and Health Sciences}%
\affil[3]{Monash Health}%


\vspace{-1em}



  
  \date{May 11, 2024}


\begingroup
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\selectlanguage{english}
\begin{abstract}
Objective: To investigate the incidence of structural and chromosomal
abnormalities in cases of fetal oedema on early ultrasound prior to
non-invasive prenatal testing (NIPT). Design: Retrospective cohort
study. Setting: Tertiary obstetric ultrasound clinic in Melbourne,
Australia. Population: Women undergoing pre-NIPT ultrasound examination
from January 2013-November 2018 with fetal crown-rump length (CRL) of
28-43 mm. Methods: Cases of reported fetal oedema or increased nuchal
thickness were included. Clinical information was collected from the
clinic's patient management database. Oedema was subclassified as
isolated nuchal oedema (\textgreater{}2.2 mm) or generalised
oedema/hydrops by two operators blinded to pregnancy outcomes. Main
Outcome Measures: Incidence of chromosomal or structural defects
following the detection of fetal oedema. Results: We identified 104
cases of reported fetal oedema with a CRL between 28-44 mm. Nuchal
oedema and generalised oedema were present in 40 (38.5\%) and 64
(61.5\%) cases respectively. Outcomes were available in 93 cases
(89.4\%). Relevant chromosomal anomalies were identified in 21.5\%
(20/93), occurring in 12.1\% (4/33) of the nuchal oedema and 26.7\%
(16/60) of the generalised oedema/hydrops cases. Structural anomalies
with normal karyotype were found in an additional four (4.3\%) cases.
Miscarriage occurred in four (4.3\%) cases and termination of pregnancy
in 18 cases (19.4\%). Oedema resolved by 11-13+6 weeks in 81.9\% and
these cases had less adverse outcomes than those with NT[?]3.5 mm (10.9\%
vs 76.5\%, p\textless{}0.001). Conclusions: Fetal oedema in early
pregnancy is associated with a high incidence of structural or
chromosomal abnormalities, and these rates increase with progressive
severity.%
\end{abstract}%



\sloppy


\textbf{INTRODUCTION}

Since the clinical implementation of non-invasive prenatal testing
(NIPT) by cell-free DNA analysis of maternal blood, the test has been
incorporated in prenatal care as a safe and accurate method for the
detection of common chromosomal abnormalities. While there are many
advantages to NIPT, the most significant is its high accuracy in
screening for trisomies 21, 18 and 13 with a detection rate of 99\% for
T21, and low false-positive rate of less than 0.1\%.\textsuperscript{1}

In its most recent guidelines on NIPT, the International Society of
Ultrasound in Obstetrics and Gynecology stated that all pregnant women
should be offered a first trimester ultrasound regardless of their
intention to undergo cell-free DNA screening.\textsuperscript{2}However,
there are no established guidelines or pathways around incorporating an
early pre-test ultrasound in current clinical practice. In a recent
study of 2,337 women who underwent an ultrasound between 10 and 14 weeks
of gestation, 16.1\% had an unexpected finding detected on the pre-NIPT
scan. These findings altered the clinical management for the patients
involved.\textsuperscript{3}

As a tertiary ultrasound unit our current model of care for NIPT is to
offer a pre-test scan between 9 and 10\textsuperscript{+6} weeks of
gestation and post-test genetic counselling. This scan provides an
opportunity to confirm viability, establish gestational age and identify
miscarriage, multiple pregnancy or early twin demise, all of which can
affect the choice of the first trimester aneuploidy screening method.
This creates an opportunity for early assessment of the fetus.

While the implications of increased nuchal translucency measurement (NT)
at the 11 to 13\textsuperscript{+6} weeks scan (crown rump length
{[}CRL{]} between 45 mm-84 mm) and its association with aneuploidy and
structural defects is well established\textsuperscript{4}, the
implications of increased nuchal translucency measurement at CRL [?] 44 mm
is unclear.

Fetal oedema at the pre-NIPT scan is a potential early marker for both
structural and chromosomal anomalies. However, in the absence of any
evidence-based guidelines this finding presents challenges in both the
counselling and management of pregnant women seeking aneuploidy
screening. In a prospective cohort study, Grande \emph{et al} .
constructed a reference range for NT in fetuses with CRL between 28-44
mm and concluded that an increased NT at this early gestation appeared
to be an effective marker for the common
aneuploidies.\textsuperscript{5} The objective of this study is to
investigate the incidence of structural and chromosomal abnormalities in
cases of reported fetal oedema on early ultrasound conducted before
NIPT.

\textbf{METHODS}

Study population

This was a single centre retrospective cohort study conducted between
January 2013 and November 2018. The cases were obtained from the
ultrasound database at Monash Ultrasound for Women, Melbourne,
Australia, which is a dedicated tertiary obstetric and gynaecological
ultrasound practice and centre for fetal diagnosis, offering first and
second trimester screening for chromosomal and structural anomalies
during pregnancy.

All patients were referred by their treating physician for cell-free DNA
screening and blood samples were collected onsite. Pre-test counselling
was provided, and informed consent was obtained. Women who opted to use
NIPT were offered an ultrasound prior to blood sampling to confirm fetal
number, viability and gestational age. They were subsequently advised to
return for fetal structural assessment between 12 and
13\textsuperscript{+6} weeks of gestational age.

Further genetic counselling was provided for those patients with fetal
oedema on the early scan and the option of either continuing with the
planned NIPT or undergoing invasive testing was made after review by an
obstetric sonologist in consultation with the referring physician and
wishes of the patient. If invasive testing was undertaken, fetal
chromosome analysis was performed by fluorescent in-situ hybridization
(FISH) plus conventional karyotyping (in cases of abnormal FISH) or
microarray analysis (in cases of normal FISH).

Procedures

The ultrasound database was searched for the terms ``oedema'', ``edema''
and for increased nuchal translucency measurements in the reports of all
pre-NIPT ultrasound examinations. Cases of singleton pregnancy with a
CRL between 28 mm and 44 mm were then selected for analysis. Early fetal
oedema was classified into two groups (see figure 1):

\begin{enumerate}
\tightlist
\item
  Nuchal oedema (figure 1B) -- increased oedema in the region of fetal
  neck \textgreater{} 2.2 mm (95\textsuperscript{th} percentile for
  nuchal translucency measurement at 10 weeks of
  gestation\textsuperscript{7}).
\item
  Generalised oedema (figure 1C) -- generalised subcutaneous oedema or
  fetal hydrops (subcutaneous oedema with at least one of pleural
  effusion, pericardial effusion or ascites).
\end{enumerate}

De-identified images and videos of cases with fetal oedema were reviewed
and classified independently by two operators with extensive experience
in obstetric ultrasound, both blinded to the outcomes. In case of
discordance, a third operator's opinion was requested.

Cases of multiple pregnancy, missed miscarriages, CRL below 28 mm or
above 45 mm or nuchal thickness less than 2.2 mm and without other signs
of fetal oedema were excluded. Ultrasound examinations were performed
using Voluson E10 (GE Healthcare Ultrasound, Zipf, Austria) machines,
equipped with a 3D 4-8 MHz probe for transabdominal and a 5-9 MHz probe
for transvaginal examinations.

Statistical analysis

Categorical variables were expressed as absolute numbers and
percentages, and continues variables were expressed in medians and
interquartile ranges (IQR). Differences in characteristics between the
study groups were examined with chi-square or Fisher's exact test in
case of categorical variables, and t test or Mann-Whitney U test for
continuous variables depending on the distribution. The agreement
between the two operators regarding classification of the type of oedema
was assessed with analysis of intraclass correlation coefficient (ICC).

The primary outcome of the study was the occurrence of chromosomal
abnormalities. Pregnancy outcomes, karyotype and microarray
abnormalities and ultrasound findings associated with early fetal oedema
are described as proportions within each group.

Finally, the association between oedema thickness with CRL 28 - 44 mm
and the nuchal translucency at 11 to 13\textsuperscript{+6} weeks was
assessed through linear regression analysis, and rates and outcomes of
persistently increased nuchal translucency above the
99\textsuperscript{th} percentile (3.5 mm) were reported. For this
purpose, adverse outcomes were defined as at least one of miscarriage,
termination of pregnancy, relevant chromosomal abnormality or major
structural defects.

A two-tailed 0.05 significance level was adopted, and statistical
analyses were performed in SPSS version 25.0\selectlanguage{ngerman}\textsuperscript{®} (IBM
Corp. Released 2017. IBM SPSS Statistics for Macintosh, Version 25.0.
Armonk, NY: IBM Corp.).

\textbf{RESULTS}

During the study period, 10,478 pre-NIPT were performed at any
gestational age and 104 cases of reported fetal oedema with a CRL
between 28 mm and 44 mm were identified. Nuchal oedema was present in 40
(38.5\%) and generalised oedema in 64 (61.5\%) cases. Fetal hydrops was
present in six of the generalised oedema cases (9.4\%).

The characteristics of the study population and pre-NIPT ultrasound are
shown in Table 1. The median maternal age was 33.6 years (interquartile
range (IQR) 30.3-37.6) and there were no significant differences in the
maternal characteristics, gestational age, oedema thickness measurement,
nuchal translucency at 11 to 13\textsuperscript{+6} weeks or cell-free
DNA test results between the subgroups of fetal oedema.

The agreement between the two operators in subclassifying the cases into
nuchal oedema, generalised subcutaneous oedema or fetal hydrops was high
(ICC 0.91, 95\%CI 0.87 -- 0.94, p\textless{}0.001).

Pregnancy outcomes were available in 93 (89.4\%) cases. Overall, in
seven cases cell-free fetal DNA testing yielded high-risk results, and
they were all true positive findings (Table 2). Relevant chromosomal
anomalies were identified in 21.5\% (20/93), occurring in 12.1\% (4/33)
of the nuchal oedema and 26.7\% (16/60) of the generalised oedema or
hydrops cases. Of the six cases of fetal hydrops, three (50\%) were
affected by trisomy 18 and three resulted in a phenotypically normal
infant at birth after low risk cfDNA testing and normal NT at 11 to
13\textsuperscript{+6} weeks.

Other structural anomalies with normal karyotype were identified in
another four (4.3\%) cases. Seventy-one infants (76.3\%) were liveborn
(66 with normal ultrasound follow up examinations and phenotypically
normal infants at birth, one with monosomy X, two with major fetal
anomalies and normal chromosomal microarray, and two with variants of
unknown significance on the chromosomal microarray). Miscarriage
occurred in four cases (4.3\%), of which three had confirmed aneuploidy
on products of conception, and termination of pregnancy was performed in
18 cases (19.4\%, 16 with chromosomal abnormalities and two with normal
karyotype but major structural anomalies at 11 to
13\textsuperscript{+6}weeks, Table 2).

There was a significant association of the oedema thickness at early
gestational age and increased nuchal translucency at 11 to
13\textsuperscript{+6} weeks (p\textless{}0.001,
R\textsuperscript{2}=0.187, Figure 1). Nevertheless, the oedema resolved
(NT below 3.5 mm) by 11 to 13\textsuperscript{+6} weeks in 81.9\% of the
cases, and these cases had a significantly lower adverse outcome rate
than those with NT \selectlanguage{english}[?] 3.5 mm (10.9\% versus 76.5\%, p\textless{}0.001).

\textbf{DISCUSSION}

Main Findings

This study showed a high incidence of chromosomal anomalies in cases of
fetal oedema diagnosed in early pregnancy, with increasing rates seen in
progressively more generalised cases of oedema. The incidence of
chromosomal anomalies increased with severity of the oedema and the
presence of hydrops (12.1\% of the nuchal oedema and 26.7\% of the
generalised oedema cases). Fetuses with reported increased nuchal
translucency had a measurement over 2.2 mm which is the
95\textsuperscript{th} percentile for gestation, based on previously
published charts for NT in fetuses with CRL \textless{} 45
mm.\textsuperscript{5} Clinically relevant chromosomal anomalies in our
series were present in more than one fifth of the cases which is higher
than expected. While fetal oedema can be seen as the presentation of
various disorders other than chromosomal anomalies, namely fetal
infection, fetal anemia secondary to conditions like thalassemia and
twin-to-twin transfusion syndrome,\textsuperscript{6} the aim of this
study was to assess the outcomes of fetal oedema with a focus on
chromosomal and structural anomalies.

Strengths and Limitations

To our knowledge, this is the first study of outcomes following
detection of oedema in fetuses with CRL between 28 mm and 44 mm in women
requesting cell-free DNA testing for aneuploidy screening.

The main limitations of this study are its retrospective design and the
fact that the database search relied on reported fetal oedema,
potentially underestimating the incidence of this finding by not
including cases where oedema was present but not mentioned in the report
due to poorly defined terms and the assumption by some reporting
physicians that mild oedema may be a normal transient finding in early
gestation. Nevertheless, it is likely that the cases with significant
oedema were captured and the incidence seems reasonable. Additionally,
fetal oedema in early pregnancy is rare and the number of cases with
fetal hydrops was small, but the higher incidence of poor outcomes in
the more severe cases is biologically plausible.

The lack of standardized definition for early fetal oedema and
differentiation between cystic hygroma and increased nuchal translucency
has been highlighted in various studies resulting in inconsistent
reporting of outcomes.\textsuperscript{6} The authors refrained from
using the term cystic hygroma to describe nuchal oedema as frequently
with the high resolution of the ultrasound probes fine septations are
seen in cases with increased nuchal translucency. Additionally, the
presence of fine septations as an independent risk factor for
chromosomal anomalies is not well established.\textsuperscript{7}

\emph{\textbf{Interpretation}}

The direct relationship of chromosomal anomalies with increasing nuchal
translucency measurements is well established in fetuses between 45 mm
and 84 mm in several studies.\textsuperscript{8, 9} However, there is
little known about this relationship in fetuses under 45 mm. A
prospective cohort study of 672 fetuses concluded that a nuchal
translucency measurement above the 95\textsuperscript{th} percentile in
fetuses at 9 to 10 weeks could be used clinically as a marker for
aneuploidy.\textsuperscript{5} The authors reported that NT was above
95\textsuperscript{th} percentile in 64\% of the fetuses with trisomy
21, 71\% of those with trisomy 13 or trisomy 18 and in all cases of
monosomy X.\textsuperscript{5} Scholl and Chasen\textsuperscript{10}have
compared the outcomes of fetuses with cystic hygroma both with CRL
\textless{} 45 mm and CRL \selectlanguage{english}[?] 45 mm and concluded that the rate of
chromosomal abnormalities and birth outcomes were lower in the CRL
\textless{} 45 mm fetuses with cystic hygroma as compared to the ones
with CRL \selectlanguage{english}[?] 45 mm. The cases in the mentioned study represent the extreme
end of the nuchal oedema group (median nuchal measurement 5.5
mm),\textsuperscript{10} while our cases included nuchal measurement
over 2.2 mm and had a median nuchal thickness of 3.1 mm. The results of
this study reinforce the value of a pre-NIPT ultrasound and suggest an
increased risk of chromosomal and structural anomalies in fetuses with
early subcutaneous oedema.

The high incidence of chromosomal and structural abnormalities in cases
of fetal oedema in early pregnancy found in this study also suggests
that in these cases and particularly in those with marked oedema or
hydrops, cell-free DNA testing may not be the ideal screening modality,
despite its high accuracy in detecting the most prevalent trisomies.
Women facing abnormal findings before 11 weeks of gestation should
receive appropriate genetic counselling and may opt for invasive testing
for genetic analysis. Regardless of which investigation method is
chosen, a detailed specialized anatomical assessment of the fetus at 11
to 13\textsuperscript{+6} weeks is needed, given that a significant
proportion of these cases, with or without chromosomal abnormalities,
will present with structural defects.

The rate of resolution of nuchal oedema at the 11 to
13\textsuperscript{+6} weeks ultrasound in our series was 81.9\%.
Although resolution of increased nuchal thickness before 14 weeks has
been previously described in only one fifth of the fetuses with early
nuchal enlargement, persistence of an increased nuchal translucency has
been consistently associated with adverse outcomes.\textsuperscript{11}

\textbf{CONCLUSION}

Fetal oedema in early pregnancy is associated with a high incidence of
structural and chromosomal abnormalities, and these rates increase with
progressive severity of fetal oedema. Identification of fetal oedema on
the pre-NIPT scan should be followed by a detailed 11 to
13\textsuperscript{+6} weeks fetal anatomy assessment and individualized
counselling regarding the different options for aneuploidy screening and
diagnosis should be offered in these cases.

\textbf{Acknowledgements}

The authors would like to acknowledge the sonographers, genetic
counselors, and doctors at Monash Ultrasound for Women involved in the
clinical care of the women in this study.

\textbf{Disclosure of interests}

The authors report no conflicts of interest.

\textbf{Contribution to Authorship}

JR, KH, CT, MM, MJM were involved in the acquisition of data, analysis
and interpretation of data and drafting and critical revision of the
manuscript. SM, JR, DLR, MM and FC led the conception and design of the
study and revised article. DLR was involved in data analysis and
interpretation, construction of tables and figures, and article
revision. All authors approve the final article.

\textbf{Details of ethics approval}

The study was conducted in accordance with the policies outlined by the
National Health and Medical Research Council and was approved by the
Monash Health Human Research Ethics Committee (HREC Ref No.
RES-19-0000-021L) on 13 March 2019.

\textbf{Funding}

No source of monetary support was provided for this research. GE
provided an E10 Ultrasound machine for research purposes which was used
in this study.

\textbf{REFERENCES}

1. Gil MM, Accurti V, Santacruz B, Plana MN, Nicolaides KH. Analysis of
Cell-Free DNA in Maternal Blood in Screening For Aneuploidies: Updated
Meta-Analysis. Ultrasound Obstet Gynecol. 2017.

2. Salomon LJ, Alfirevic Z, Audibert F, Kagan KO, Paladini D, Yeo G, et
al. ISUOG updated consensus statement on the impact of cfDNA aneuploidy
testing on screening policies and prenatal ultrasound practice.
Ultrasound Obstet Gynecol. 2017;49(6):815-6.

3. Vora NL, Robinson S, Hardisty EE, Stamilio DM. Utility of ultrasound
examination at 10-14 weeks prior to cell-free DNA screening for fetal
aneuploidy. Ultrasound Obstet Gynecol. 2017;49(4):465-9.

4. Kagan KO, Sonek J, Wagner P, Hoopmann M. Principles of first
trimester screening in the age of non-invasive prenatal diagnosis:
screening for chromosomal abnormalities. Arch Gynecol Obstet.
2017;296(4):645-51.

5. Grande M, Solernou R, Ferrer L, Borobio V, Jimenez JM, Bennasar M, et
al. Is nuchal translucency a useful aneuploidy marker in fetuses with
crown-rump length of 28-44 mm? Ultrasound Obstet Gynecol.
2014;43(5):520-4.

6. Beke A, Joo JG, Csaba A, Lazar L, Ban Z, Papp C, et al. Incidence of
chromosomal abnormalities in the presence of fetal subcutaneous oedema,
such as nuchal oedema, cystic hygroma and non-immune hydrops. Fetal
Diagn Ther. 2009;25(1):83-92.

7. Mack LM, Lee W, Mastrobattista JM, Belfort MA, Van den Veyver IB,
Shamshirsaz AA, et al. Are First Trimester Nuchal Septations Independent
Risk Factors for Chromosomal Anomalies? Journal of ultrasound in
medicine : official journal of the American Institute of Ultrasound in
Medicine. 2017;36(1):155-61.

8. Kagan KO, Avgidou K, Molina FS, Gajewska K, Nicolaides KH. Relation
between increased fetal nuchal translucency thickness and chromosomal
defects. Obstet Gynecol. 2006;107(1):6-10.

9. Molina FS, Avgidou K, Kagan KO, Poggi S, Nicolaides KH. Cystic
hygromas, nuchal edema, and nuchal translucency at 11-14 weeks of
gestation. Obstet Gynecol. 2006;107(3):678-83.

10. Scholl J, Chasen ST. First trimester cystic hygroma: does early
detection matter? Prenat Diagn. 2016;36(5):432-6.

11. Muller MA, Pajkrt E, Bleker OP, Bonsel GJ, Bilardo CM. Disappearance
of enlarged nuchal translucency before 14 weeks' gestation: relationship
with chromosomal abnormalities and pregnancy outcome. Ultrasound Obstet
Gynecol. 2004;24(2):169-74.

\textbf{FIGURES}

Figure 1: Oedema classification



\textbf{TABLES}

Table 1. Characteristics of the study population.\selectlanguage{english}
\begin{longtable}[]{@{}llll@{}}
\toprule
\begin{minipage}[b]{0.22\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[b]{0.22\columnwidth}\raggedright\strut
\textbf{Nuchal oedema} \textbf{n = 40 (38.5\%)}\strut
\end{minipage} & \begin{minipage}[b]{0.22\columnwidth}\raggedright\strut
\textbf{Subcutaneous oedema or hydrops} \textbf{n = 64 (61.5\%)}\strut
\end{minipage} & \begin{minipage}[b]{0.22\columnwidth}\raggedright\strut
\textbf{Total} \textbf{N = 104}\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Maternal age (years)}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
32.6 (30.1-37.5)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
33.7 (30.6-37.8)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
33.6 (30.3-37.6)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Weight (Kg)}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
61.0 (53.9-72.3)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
64.0 (58.0-70.0)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
64.0 (55.3-70.0)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Height (cm)}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
160.5 (158.0-166.5)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
163.0 (158.0-169.0)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
162.0 (158.0-168.0)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Body mass index (kg/m\textsuperscript{2})}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
23.0 (20.0-27.8)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
23.9 (21.1-26.3)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
23.4 (20.8-26.9)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Parity}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
\textbf{Nulliparous}\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
19 (47.5)\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
33 (51.6)\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
52 (50.0)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
\textbf{Parous}\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
21 (52.5)\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
31 (48.4)\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
52 (50.0)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Previous chromosomal abnormality}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
2 (5.0)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
4 (7.8)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
7 (6.7)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Gestational age at pre-NIPT ultrasound (weeks)}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
10.5 (10.4-10.7)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
10.6 (10.4-10.9)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
10.6 (10.4-10.9)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Conception}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
\textbf{Spontaneous}\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
36 (90.0)\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
56 (87.5)\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
92 (88.5)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
\textbf{IVF}\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
4 (10.0)\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
8 (12.5)\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
12 (11.5)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Crown-rump length (mm)}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
39.4 (35.8-40.7)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
39.4 (36.0-41.6)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
39.4 (26.0-41.3)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Oedema thickness [?] 10+6 weeks (mm)}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
3.2 (2.6-3.8)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
3.1 (2.5-4.1)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
3.1 (2.5-4.1)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{Nuchal translucency 11-13+6 weeks (mm)}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
2.5 (2.2-3.0)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
2.4 (1.9-3.2)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
2.5 (2.0-3.1)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
\textbf{High risk cell-free DNA test}\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
2/34 (5.9)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
5/51 (9.8)\strut
\end{minipage} & \begin{minipage}[t]{0.22\columnwidth}\raggedright\strut
7/85 (8.2)\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

Categorical variables are given in absolute number and percentages,
continuous variables are given in medians and interquartile ranges.

Table 2. Associations with chromosomal and structural abnormalities in
each fetal oedema subgroup.\selectlanguage{english}
\begin{longtable}[]{@{}llll@{}}
\toprule
\begin{minipage}[b]{0.22\columnwidth}\raggedright\strut
\strut
\end{minipage} & \begin{minipage}[b]{0.22\columnwidth}\raggedright\strut
\textbf{Chromosomal abnormalities}\strut
\end{minipage} & \begin{minipage}[b]{0.22\columnwidth}\raggedright\strut
\textbf{Structural abnormalities with normal CMA}\strut
\end{minipage} & \begin{minipage}[b]{0.22\columnwidth}\raggedright\strut
\textbf{Pregnancy outcomes}\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
\textbf{Nuchal oedema (n =33)\textsuperscript{*}}\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
Trisomy 18, one Trisomy 21, one Monosomy X, one Mosaic Monosomy X / 46,
X,idicY(q11.2), one\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
Right atrial isomerism, Bilateral thumb abnormalities, Duodenal
stenosis, one Transposition of the great arteries, one\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
Miscarriages, two TOP, three Live births with fetal abnormalities, two
Live births of phenotypically normal infants, 26 (two with VOUS)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
\textbf{Generalised oedema (n = 60)\textsuperscript{*}}\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
Trisomy 18, six Trisomy 21, three Trisomy 22, one Monosomy X, two
Trisomy 18 and trisomy X, one 2.48 Mb deletion 4p16.3, one Duplication
8p23.3p11.21 and deletion 9p24.3p22.3, one Heterozygous deletion 15q11.2
and CNG 17q12, one\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
Hypoplastic left heart syndrome, one Single umbilical artery and cord
cyst, one Short femur and FGR, one Duplex left kidney, one\strut
\end{minipage} & \begin{minipage}[t]{0.24\columnwidth}\raggedright\strut
Miscarriages, two TOP, 15 Live birth with monosomy X, one Live births of
phenotypically normal infants, 42\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

\textsuperscript{\textbf{*}} Including cases with known pregnancy
outcome. CMA: chromosomal microarray; Mb: mega-bases; CNG: copy number
gain; TOP: Termination of pregnancy; VOUS: variant of unknown
significance on chromosomal microarray\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-1A/Figure-1A}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-1B/Figure-1B}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-1C/Figure-1C}

\end{center}
\end{figure}

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

