Impact of interpregnancy interval on the subsequent risk of adverse perinatal outcomes

The aim of this study was to investigate the impact of interpregnancy interval as a risk factor on multiple adverse perinatal outcomes.

Interpregnancy intervals and confounding factors were determined for healthy pregnancies (controls [n = 357]) and for pregnancies complicated by adverse perinatal outcomes. Interpregnancy interval was categorized as <6, 6-11, 12-17, 18-23, 24-35 and ≥36 months. Adverse outcomes included spontaneous labor leading to preterm birth (n = 265), preterm premature rupture of membranes (n = 245), pre-eclampsia (n = 286), gestational diabetes (n = 302), abnormal placentation (n = 154), anemia (n = 314), congenital anomalies (n = 459), post-partum hemorrhage (n = 326) and small for gestational age (n = 168). Multivariate logistic regression analysis was performed to assess the association of each outcome with the interpregnancy interval categories.

Spontaneous labor leading to preterm birth (odds ratio [OR], 1.86; 95% confidence interval [CI], 1.13-1.97), preterm premature rupture of membranes (OR, 1.69; 95%CI, 1.28-2.39), congenital anomalies (OR, 1.38; 95%CI, 1.09-1.76) and small for gestational age (OR, 1.68; 95%CI, 1.14-2.34) were significantly associated with intervals of <6 months. Among congenital anomalies, short interpregnancy interval represents an increased risk for cardiac defects (OR, 1.55; 95%CI, 1.09-5.46), neural tube defects (OR, 2.06; 95%CI, 1.32-7.64) and central nervous system anomalies (OR, 1.45; 95%CI, 1.12-3.65).

Short interpregnancy interval is an independent risk factor for adverse perinatal outcomes.