What is the optimal time between pregnancies for women over 30?

Date posted: 
Thursday, May 26, 2016

Women are increasingly delaying childbearing to pursue educational or career goals, or to achieve financial stability before having children. Pregnancies to women at older ages are at increased risk for adverse outcomes compared with pregnancies to younger women. In addition, short inter-pregnancy intervals, more common among women who have delayed childbearing, are associated with increased risks of adverse pregnancy and birth outcomes. Older women have to balance the potential risks associated with short inter-pregnancy intervals against their increasing age, with little data to inform this decision.

Laura Schummers, a doctoral student in Epidemiology at the Harvard T.H.Chan School of Public Health, aims to provide much needed evidence to help older women making their family planning decisions by identifying the optimal inter-pregnancy interval for women who delay childbearing until after they are 30.

The recommended inter-pregnancy interval for the general population is 18-23 months between delivery and subsequent pregnancy. The research project aims to find out whether this recommendation is applicable to women over 30 or whether specific guidelines targeting an older population are necessary.

“Most studies of age at pregnancy typically present risks in terms of odds ratios comparing women older or younger than 35 or 40,” says Ms Schummers, who is co-supervised by UBC Assistant Professor Jennifer Hutcheon, in the Faculty of Medicine’s Department of Obstetrics and Gynaecology. “Findings presented in this way are not easy to interpret either for clinicians or for the public. One of our aims is to estimate the absolute risk of important adverse pregnancy and birth outcomes, such as preeclampsia and gestational diabetes, according to 1-year increments of maternal age at pregnancy, to provide the most intuitive and interpretable results.”

Ms Schummers hopes that study findings will inform pre-pregnancy counseling and public health messaging and lead to improved population-level perinatal health outcomes.

For the study, Population Data BC will link BC Ministry of Health, BC Vital Statistics Agency and Statistics Canada data with data from PharmaNet and the BC Perinatal Database.

Page last revised: May 26, 2016