A latest study by researchers at the Mailman School of Public Health and Columbia University Medical Center reports that pre-eclampsia, characterized by an elevation in the blood pressure and excess protein in the urine of pregnant women, has a 1.5-fold to 2-fold higher incidence in first pregnancies. The condition, which causes complications in approximately 3-6% of all pregnancies, is also associated with high risks of preterm delivery, intrauterine growth restriction, placental abruption, and perinatal mortality. Findings are published online in the British Medical Journal.
The study by Drs. Cande Ananth, Katherine Keyes, and Ronald Wapner in the Departments of Epidemiology and Obstetrics and Gynecology, examined data on 120 million births in the United States between 1980 and 2010 from national hospital discharge surveys. This is the largest cohort study to analyze changes in rates of pre-eclampsia in the U.S.
According to findings, pre-eclampsia rates rose from 3.4% in 1980 to 3.8% in 2010. This increase was due to the rise in rates of severe pre-eclampsia — from 0.3% in 1980 to 1.4% in 2010, a relative increase of 322%. At the same time, rates of mild pre-eclampsia declined, from 3.1% in 1980 to 2.5% in 2010. Women born in the mid-1970s were at increased risk for mild pre-eclampsia, whereas women born in the more recent periods showed an increased risk of severe pre-eclampsia, suggesting a birth cohort effect. The researchers note that the increasing obesity and decreasing smoking rates in the United States across the last three decades explain, at least in part, the trends in the observed pre-eclampsia rates.
Particularly noteworthy is the fact that the researchers analyzed data collected across 30 years to understand the association of maternal age with time of disease occurrence and mother’s date of birth on rates of pre-eclampsia. Results suggest that reducing obesity rates could also be favorable to a reduction in pre-eclampsia rates.