Main Findings and Interpretation
As reported in previous studies, results of our analyses suggest that
there are racial/ethnic differences in the prevalence of PDM and GDM.
However, our findings expand on previous studies by reporting data on
trends in pregnancy-associated diabetes by race/ethnicity. Consistent
with earlier HCUP NIS studies, our results show an increasing trend in
the prevalence of PDM and GDM from 2002 to 2017.10 In
addition, our data suggest the prevalence of PDM and GDM is increasing
among NH-White, NH-Black and Hispanic hospitalized mothers. These
findings correlate with increasing trends in risk factors for diabetes
such as obesity, inactivity, and hypertension observed among specific
racial/ethnic minority women.25–30 Another possible
contributing factor is an increase in advanced maternal age
pregnancies.31–33
Note that the graphs in Figure 1 show an inflection point in trends for
PDM and GDM in 2015. This is likely caused by two factors. First, the
implementation of U.S. Prevent Services Task Force recommendations for
routine GDM screening in asymptomatic pregnant women after 24 weeks of
pregnancy in 2014.34 Secondly, a change in disease
reporting in 2015 due to the transition from the ICD-9 to ICD-10 coding
set.35 These changes likely increased screening for
PDM and GDM as well as disease reporting.
The majority of associations we found between pregnancy-associated
diabetes, race/ethnicity and maternal characteristics are consistent
with previously reported data.10,36,37 One exception
is the increase in GDM prevalence with increasing zip code income
observed among hospitalized NH-Black and Hispanic women. A previously
published study conducted in California found that high-income zip codes
had a lower prevalence of GDM compared to low-income zip
codes.38 These conflicting results suggest that
factors such as diabetes screening, exercise, and diet could be more
important than previously suspected to the prevalence of GDM in certain
racial/ethnic groups.
The highest prevalence rates for PDM and GDM were observed among
Hispanic and NH-Black pregnant mothers discharged against medical advice
(DAMA). Previously published data suggest DAMA is more common among
hospitalized pregnant women with PDM and GDM compared to those without
diabetes.39 DAMA among hospitalized pregnant women is
also associated with Black race, public insurance, substance abuse,
mental illness, chronic hypertension, neonatal morbidity and fetal
death.40 Additional research is needed to better
characterize this vulnerable group and develop screening tools for
intervention.
Another notable finding is the prevalence of PDM among NH-Black pregnant
women who died during hospitalization. Among pregnant women who died
during hospitalization, NH-Black had the highest prevalence of PDM when
compared to the other race/ethnic groups. Our results are consistent
with previously published NIS data.41 The causal
pathway between PDM and maternal mortality among hospitalized NH-Black
women is not clear but studies report African American race/ethnicity is
a significant independent risk-factor for pregnancy-related
cardiovascular conditions including venous thromboembolism and stroke
that can be fatal.42,43 Further, type 1 diabetes has
been associated with an increased risk of maternal mortality due to
complications such as hypoglycemia.44 These data
suggest NH-Black pregnant women with PDM could be predisposed to
glycemic and cardiovascular conditions that increase risk for maternal
mortality. However, additional research is needed.
Consistent with previously published data, stillbirth rates for
hospitalized pregnant women in our study were higher for women with PDM
than those with GDM.12,14 Unlike previous studies,
results of our analyses show that racial/ethnic differences in
stillbirth rates exist. Additionally, we are the first to report
adjusted odds of stillbirth for Hispanic mothers with PDM. Hispanic
mothers with PDM had the highest adjusted odds of stillbirth when
compared to their non-diabetic counterparts in our study, a previously
unreported finding. Reasons for differences across racial/ethnic groups
are likely underlying maternal and fetal characteristics that have not
been well-studied. Previously reported risks factors for stillbirth
among woman with PDM include maternal age, BMI, gestational infant size,
male gender, parity, tobacco use and type of
delivery.18,35,37,45 The extent to which these factors
are influenced by race/ethnicity is not clear and should be taken into
consideration.
Interestingly, after adjustment for maternal and hospital
characteristics, we found that GDM was protective for stillbirth in each
race/ethnic group, decreasing the odds of stillbirth by approximately
50%. Similar findings are reported by Lavery et al.46One possible explanation could be related to the large percentage
(70-78%) of women in our study with private or public medical coverage.
Medical coverage may result in more aggressive diabetes screening during
pregnancy and better access to follow-up care decreasing the occurrence
of stillbirth.