Preeclampsia and fetal growth

Objective: To determine if the influence of preeclampsia on birth size vari es with clinical manifestations of the disease, and to evaluate whether mat ernal factors, such as smoking, modify the effect of preeclampsia on fetal growth. Methods: Among 12,804 deliveries in a population of approximately 239,000 o ver a 3-year period, 307 live singleton infants were born after preeclampti c pregnancies. We compared those with a sample of 619 control infants. Pree clampsia was defined as increased diastolic blood pressure (BP) (increase o f at least 25 mmHg to at least 90 mmHg) and proteinuria after 20 weeks' ges tation. Clinical manifestations were classified according to BP and protein uria into subgroups of mild, moderate, or severe (including cases with ecla mpsia and hemolysis, elevated liver enzymes, low platelets [HELLP] syndrome ) preeclampsia, and according to gestational age at onset, as early or late preeclampsia. Birth size was expressed as the ratio between observed and e xpected birth weights, and infants smaller than two standard deviations fro m expected birth weights were classified as small for gestational age (SGA) . Results: Preeclampsia was associated with a 5% (95% confidence interval [CI ] 3%, 6%) reduction in birth weight. In severe preeclampsia, the reduction was 12% (9%, 15%), and in early-onset disease, birth weight was 23% (18%, 2 9%) lower than expected. The risk of SGA was four times higher (relative ri sk [RR] = 4.2; 95% CI 2.2, 8.0) in infants born after preeclampsia than in control pregnancies. Among nulliparas, preeclampsia was associated with a n early threefold higher risk of SGA (RR = 2.8; 1.2 5.9), and among paras, th e risk of SGA was particularly high after recurrent preeclampsia (RR = 12.3 ; 3.9, 39.2]. In relation to preeclampsia and maternal smoking, the results indicated that each factor might contribute to reduced growth in an additi ve manner. Conclusion: Severe and early-onset preeclampsia were associated with signif icant fetal growth restriction. The risk of having an SGA infant was dramat ically higher in women with recurrent preeclampsia. Birth weight reduction related to maternal smoking appeared to be added to that caused by preeclam psia, suggesting that there is no synergy between smoking and preeclampsia on growth restriction. (Obstet Gynecol 2000;96:950-5. (C) 2000 by The Ameri can College of Obstetricians and Gynecologists.).