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210: Fetal growth patterns in hypertensive disorders of pregnancy: the NICHD fetal growth studies

      Objective

      We lack an understanding of longitudinal patterns of fetal growth in pregnancies that develop hypertensive disease. Our objective was to compare longitudinal fetal growth trajectories between normotensive pregnancies and those complicated by pregnancy-induced hypertensive disorders.

      Study Design

      This is a secondary analysis of a multicenter longitudinal study of fetal growth. Dating was assured by ultrasound between 8w0d and 13w6d and women had six targeted ultrasounds across gestation. Women were grouped as mild or severe gestational hypertension (mild-GHTN or severe-GHTN), mild or severe preeclampsia (mild-PE or severe-PE), and no-hypertension (no-HTN) based on the discharge diagnosis. Growth curves for estimated fetal weight (EFW) and individual biometric parameters were created using linear mixed models with cubic splines. Global and weekly pair-wise comparisons were performed between groups to analyze differences adjusting for confounding variables.

      Results

      Of the 2,584 pregnancies analyzed, 2402 (92.9%) were normotensive, 65 (2.5%) mild-GHTN, 58 (2.2%) mild-PE, and 34 (1.3%) severe-PE. Seven women with severe-GHTN were excluded due to the small number. Compared to other groups, EFW was reduced in the severe-PE group distinguishing itself from 21 weeks onward (weekly pairwise P values <.05; Figure). Significant reductions were also noted in the abdominal circumference growth between no-HTN and severe-PE groups from 21 to 38 weeks’ gestation (weekly pairwise P values <.05), head circumference from 24 to 32 weeks, and some scattered differences in other parameters. EFW and individual biometrics had scattered differences among mild-GHTN, mild-PE, and normotensive pregnancies, but the magnitude of these differences was comparatively small.

      Conclusion

      Among hypertensive disorders of pregnancy, only pregnancies destined to develop severe-PE had a significant and consistent adverse effect on fetal growth. Severe-PE is associated with an early- onset fetal growth restriction.
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