Pregnancies following short interpregnancy intervals (conceived within 12 or 18 months of a prior delivery) have increased risks of adverse pregnancy outcomes, including preterm birth, small-for-gestational age, and infant death. Thus, current guidelines recommend that women wait at least 18 months before becoming pregnant again. However, experts have raised concerns that these guidelines may not be appropriate for specific high-risk populations, such as women whose index pregnancy ended in a perinatal loss, preterm birth, or those with a history of subfertility. These high-risk populations have an urgent need for specific, targeted pregnancy spacing recommendations, but currently have the least evidence available to inform decision-making.
Data access has been approved for a project which builds on the results of a previous study which determined the optimal interpregnancy interval for women who delayed childbearing to age 30. The latest project includes more specific high-risk obstetric populations and key covariates, and a longer study period.
One of the aims of the study is to establish the interpregnancy interval range associated with lowest risks of adverse pregnancy outcomes among women with a perinatal loss in the first pregnancy.
“Women with a previous perinatal loss are among the most vulnerable and high-risk obstetric patients,” says project lead Dr. Laura Schummers, Assistant Professor in the Faculty of Pharmaceutical Sciences at University of British Columbia. “Risk of recurrent stillbirth and neonatal mortality are 4-fold higher among women with an index loss than those with an index livebirth, and risks of fetal growth restriction and preterm birth are also increased. Thus, this population has a clear need for targeted recommendations to optimize outcomes in future pregnancies. It is not known whether short intervals further increase risks or whether short intervals may be advisable in this specific group.”
Other project objectives include: establishing the interpregnancy interval range associated with lowest risks of adverse pregnancy outcomes among women who conceived the first pregnancy using oral ovulation stimulation infertility treatment; and establishing the interpregnancy interval range associated with lowest risks of adverse pregnancy outcomes among women with a spontaneous preterm birth in the first pregnancy.
The study population includes all females of reproductive age (12-49) in British Columbia from April 1, 2004 and December 31, 2020. PopData will link seven data sets from the BC Ministry of Health with data from the BC Perinatal Data Registry for the project.