Pregravid Oral Contraceptive Use and the Risk of Preterm Birth, Low Birth Weight, and Spontaneous Abortion: A Systematic Review and Meta-Analysis.

Although oral contraceptives (OCs) have been widely used by women of childbearing age, their influence on pregnancy and birth outcomes, such as preterm birth (PB), low birth weight (LBW), and spontaneous abortion (SAB), is unclear. The aim of this systemic review was to assess these complications in women who had used OCs before pregnancy compared with those in a control group. The databases of PubMed, EMBASE, and Web of Science were searched up to December 2018. We included studies where the primary outcome was the risk of PB, LBW, and SAB in women with pregravid OCs use compared with the control group. Odds ratio (OR) value was calculated to assess the risk. Eighteen studies were included in the systematic review, and a total of 148,406 subjects from 7 studies were pooled for the meta-analysis. Results showed that the risk of PB was slightly higher in the exposed group (OR = 1.17, 95% confidence interval [CI] = 1.07-1.27,  = 0.0005); however, there was a lower risk for SAB compared with the control group (OR = 0.63, 95% CI = 0.41-0.96,  = 0.03). No significant difference was found in the incidence of LBW (OR = 1.36, 95% CI = 0.92-2.02,  = 0.12). This systematic review and meta-analysis demonstrated a higher risk for PB and a lower risk for SAB in women with previous ORs use, whereas no association was found between ORs use and LBW risk.