Abstract
Objective The purpose of our study was to evaluate the body mass index (BMI)-specific association
between early gestational weight gain (GWG) in dichorionic twin pregnancies and the
risk of preeclampsia.
Study Design We conducted a retrospective cohort study of all dichorionic twin pregnancies from
1998 to 2013. Data were obtained from a perinatal database and chart abstraction.
Prepregnancy BMI was categorized as normal (18.5–24.9 kg/m2), overweight (25–29.9 kg/m2), and obese (≥30 kg/m2). Early GWG was defined as the last measured weight from 160/7 to 196/7weeks' gestation minus prepregnancy weight. GWG was standardized for gestational duration
using BMI-specific z-score charts for dichorionic pregnancies. Preeclampsia was diagnosed using American
College of Obstetricians and Gynecologists criteria and identified with International
Classification of Diseases-9 coding. Early GWG z-score was modeled as a three-level categorical variable (≤ − 1 standard deviation
[SD], 0, 3 +1 SD), where −1 to +1 was the referent group. We estimated risk differences
and 95% confidence intervals (CIs) via marginal standardization.
Results We included 1,693 dichorionic twin pregnancies in the cohort. In adjusted analysis,
the incidence of preeclampsia increased with increasing early GWG among women with
normal BMI. Women with normal BMI and a GWG z-score < − 1 (equivalent to 2.6 kg by 20 weeks) had 2.5 fewer cases of preeclampsia
per 100 births (95% CI: −4.7 to − 0.3) compared with the referent; those with GWG
z-score > +1 (equivalent to gaining 9.8 kg by 20 weeks) had 2.8 more cases of preeclampsia
per 100 (95 % CI: 0.1–5.5) compared with the referent. In adjusted analyses, early
GWG had minimal impact on the risk of preeclampsia in women with overweight or obesity.
Conclusion GWG of 2.6 kg or less by 20 weeks was associated with a decreased risk of preeclampsia
among women pregnant with dichorionic twins and normal prepregnancy BMI. Current GWG
guidelines focus on optimizing fetal weight and gestational length. Our findings demonstrate
the importance of considering other outcomes when making GWG recommendations for twin
pregnancy.
Key Points
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Early GWG decreased with increasing BMI category.
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Among women with normal weight, as early GWG increased so did the risk of preeclampsia.
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There was no association between early GWG and preeclampsia among women with overweight
or obesity.
Keywords
gestations - preeclampsia - early gestational weight gain - dichorionic twins
