Blood Pressure in Different Gestational Trimesters, Fetal Growth, and the Risk of Adverse Birth Outcomes

Researchers have suggested that maternal hypertensive disorders during pregnancy affect fetal growth. The authors examined the associations between systolic and diastolic blood pressures in different trimesters of pregnancy and both repeatedly measured fetal growth characteristics and the risks of adverse birth outcomes. The present study (2001-2005) was performed in 8,623 women who were participating in a population-based prospective cohort study from fetal life onwards. Blood pressure and fetal growth characteristics were assessed in each trimester of pregnancy. Information on hypertensive complications and adverse birth outcomes was obtained from medical records. The results suggested that higher blood pressure was associated with smaller fetal head circumference and femur length, as well as lower fetal weight from the third trimester onward. An increase in blood pressure from the second trimester to the third trimester was associated with an increased risk of adverse birth outcomes. Compared with women who did not experience hypertension during pregnancy, women with preeclampsia had increased risks of having children who were preterm (odds ratio = 5.89, 95% confidence interval: 2.63, 13.14), had a low birth weight (odds ratio = 8.94, 95% confidence interval: 6.19, 12.90), or were small for their gestational age (odds ratio = 5.03, 95% confidence interval: 3.31, 7.62). The present results suggest that higher maternal blood pressure is associated with impaired fetal growth during the third trimester of pregnancy and increased risks of adverse birth outcomes.