Association between inter-pregnancy interval and risk of adverse birth outcomes in subsequent pregnancy: A retrospective study from Jordan

Background: Adverse birth outcomes, such as preterm birth and low birth weight (LBW), are leading causes of neonatal morbidity and mortality. In this study, we aimed to estimate the association between inter-pregnancy interval (IPI) and the risks of adverse birth outcomes in a subsequent pregnancy. Methods: We conducted a retrospective analysis involving 630 mothers who delivered a singleton live infant at a leading tertiary hospital in northern Jordan from March to August 2021. Outcome variables were preterm birth (<37 weeks of gestation) and LBW (<2.5 kg). Using multivariable logistic regression, the association between IPI and these two adverse birth outcomes was investigated. Results: The rates of preterm birth and LBW were 12.4% and 16.8%, respectively. Compared with an optimal IPI (24–36 months), a short IPI (<24 months) was positively associated with preterm birth (aOR: 4.09; 95% CI: 1.48–6.55) and LBW (aOR: 3.58; 95% CI: 1.57–5.15). Infants conceived after a long IPI (≥ 60 months) had increased odds of preterm birth (aOR: 3.78; 95% CI: 1.12–5.78) and LBW (aOR: 2.65; 95% CI: 1.67–4.03). Preterm delivery was also significantly associated with the mother's age (aOR: 1.10; 95% CI: 1.04–1.17), history of multiple cesarean births (aOR: 2.67; 95% CI: 1.14–4.29), prolonged rupture of membranes (aOR: 2.46; 95% CI: 1.10–5.52), and perinatal death (aOR: 3.42; 95% CI: 1.10–5.49). A mother's history of prior LBW (aOR: 4.39; 95% CI: 1.08–6.80), hypertensive disorders (aOR: 1.95; 95% CI: 1.03–3.89), and multiple cesarean births (aOR: 4.35; 95% CI: 2.10–6.99) was associated with LBW. Conclusions: Both short and long IPIs were related to preterm delivery and LBW. Optimal birth spacing is recommended to improve birth outcomes and must be considered when designing effective family planning programs.