Chronic Hypertension and Pregnancy : Epidemiological Aspects on Maternal and Perinatal Complications

These studies were undertaken to investigate risks of maternal and perinatal complications in pregnant women with chronic hypertensive disease, and to investigate future risk of preeclampsia in women born small for gestational age (SGA). Population based cohort studies using the Swedish Medical Birth Register from different years were performed. The maternal complications mild and severe preeclampsia, gestational diabetes and abruptio placenta were studied in a population of 681 515 women, with a prevalence of 0,5% for chronic hypertension. Risk estimates were adjusted for differences in maternal characteristics as age, parity, BMI, ethnicity and smoking habits. Chronic hypertensive women wore found to have significantly increased risks of all complications. The perinatal complication SGA was studied in a population of 560 188, with a prevalence of 0,5% for chronic hypertension. Risk estimates were adjusted for differences in maternal characteristics and for the secondary complications mild and severe preeclampsia. Chronic hypertensive women were found to suffer a significantly increased risk of giving birth to an offspring that is SGA. The perinatal complication fetal/infant mortality was studied in a population of 1 222 952 with a prevalence of 0,6% for chronic hypertension. Risk estimates were adjusted for differences in maternal characteristics and for the complications mild and severe preeclampsia, gestational diabetes, abruptio placenta and offspring being SGA In the analysis an effect modification by gender was included. Chronic hypertensive women were found to have a significantly increased risk for stillbirth and neonatal death in male, but not in female, offspring. Thus a clear gender difference in mortality was revealed. The risk of mortality of offspring was mediated by severe preeclampsia, abruptio placenta and offspring being SGA. Mild preeclampsia and gestational diabetes did not affect the risk. No increased risk of post neonatal mortality was found. A generation study was performed in 118 634 girls of which 5.8% were born SGA. Their future risk for mild and severe preeclampsia in first pregnancy was analysed. Risk estimates were adjusted for age, smoking, BMI and for preeclampsia in the mothers while pregnant with the study population. Women who were born SGA were shown to have a significantly increased risk for severe preeclampsia, but not for mild preeclampsia