Interbirth Interval and Pregnancy Complications and Outcomes: Findings from the Pregnancy Risk Assessment Monitoring System

INTRODUCTION:Although the definition of a short interbirth interval has been inconsistent in the literature, Healthy People 2020 recommends that women wait at least 18 months after a live birth before attempting their next pregnancy. In the United States, approximately 33% of pregnancies are conceived within 18 months of a previous birth. Pregnancies that result from short interbirth intervals can pose serious risks. The objective of this study was to determine the association between interbirth interval and understudied pregnancy complications and outcomes, including small for gestational age (SGA) infants, premature rupture of membranes (PROM), preterm PROM (PPROM), placenta previa, and gestational diabetes, using Pregnancy Risk Assessment and Monitoring System data from Mississippi and Tennessee. METHODS:This study collected self-reported information from 2212 women on interbirth interval (≤18 months, ie, short; 19-35 months, ie, intermediate; and ≥36 months, ie, long; referent), PPROM, placenta previa, and gestational diabetes. SGA and PROM data were obtained from birth certificates. Logistic regression was used to calculate odds ratios (ORs) and 95% CIs. RESULTS:After adjustment, there were no strong associations between interbirth interval and PPROM, gestational diabetes, or SGA infants. However, women with shorter intervals had increased odds of PROM (short: OR, 3.54; 95% CI, 1.22-10.23 and intermediate: OR, 4.09; 95% CI, 1.28-13.03) and placenta previa (short: OR, 2.58; 95% CI, 1.10-6.05 and intermediate: OR, 1.69; 95% CI, 0.94-3.05). DISCUSSION:The study's findings provide further support for encouraging women to space their pregnancies appropriately. Moreover, findings underscore the need to provide women with family planning services so that closely spaced pregnancies and unintended pregnancies can be avoided. Additional studies of the role of interbirth interval on these understudied pregnancy complications and outcomes are warranted.