Inter-pregnancy interval and long-term neurological morbidity of the offspring.

Purpose: The purpose of our study was to evaluate the effect of IPI on long-term neurological morbidity of the offspring.
Methods: In this retrospective cohort study, 144,397 singleton infants born to multiparous mothers, between the years 1991 and 2014 in a tertiary medical center, were evaluated for different perinatal outcomes and were followed until 18 years of age for long-term neurological morbidity according to three IPI groups: Short IPI (< 6 months), long IPI (> 60 months) and intermediate IPI (6-60 months). We used a Kaplan-Meier survival curve to compare cumulative incidence of long-term neurological morbidity, and a Cox regression analysis to control for confounders such as gestational age, birth weight and maternal age.
Results: Offspring born to mothers with long IPI had higher rates of neurological morbidity (3.62% among offspring born after long IPI vs. 3.18% and 3.19% among offspring born after short and intermediate IPI, respectively, p = 0.041). The cumulative incidence of long-term neurological morbidity was significantly higher in the long IPI group (Kaplan-Meier log-rank test p < 0.001). Being born after a long IPI was found to be an independent risk factor for long-term neurological morbidity of the offspring (adjusted hazard ratio 1.2; 95% confidence interval 1.1-1.4; p < 0.001).
Conclusion: Long IPI is independently associated with an increased risk of long-term neurological morbidity of the offspring.