Interpregnancy interval and adverse perinatal outcomes in Somalia: a single-center retrospective linked-pregnancy cohort study

Short interpregnancy intervals (IPIs) are associated with adverse perinatal outcomes, but effect estimates vary across populations and evidence from Somalia is scarce despite frequent short birth spacing and substantial barriers to maternal and newborn care. We evaluated this association in a tertiary referral hospital in Mogadishu. This retrospective linked-pregnancy cohort included women aged 18–40 years with a singleton index delivery at ≥ 28 completed weeks between 1 January 2019 and 1 September 2025, an immediately preceding delivery at ≥ 28 weeks in the same hospital, and verifiable linked records for pregnancy chronology and dating, the primary outcome, and early neonatal vital status. IPI was calculated from the preceding delivery to the last-menstrual-period-equivalent estimated startstart of the index pregnancy and categorized as < 6, 6–11, 12–17, 18–23, or ≥ 24 months; 18–23 months was the reference. The primary composite comprised preterm live birth at 28 + 0–36 + 6 weeks, low birthweight, small for gestational age, stillbirth, or early neonatal death. Modified Poisson regression estimated adjusted risk ratios (aRRs). The primary model adjusted for demographic and reproductive-history confounders; a secondary conditional model additionally included antenatal-care attendance and maternal anemia. Standardized risks were estimated separately by marginal standardization using primary-model covariates. Of 12,686 delivery records screened, 464 unique women (one linked consecutive-pregnancy pair each) were included. The primary outcome occurred in 160 of 464 index pregnancies (34.5%), with rates of 58.5%, 67.9%, 39.2%, 13.9%, and 19.7% across increasing IPI categories. Compared with 18–23 months, primary-model aRRs were 2.35 (95% CI 1.32–4.19), 2.85 (1.69–4.80), 1.83 (1.06–3.18), and 1.36 (0.78–2.39), respectively. Separately standardized risks were 44.8%, 56.0%, 33.6%, 20.1%, and 26.0%. A + 14-day conception-dating sensitivity analysis modestly attenuated estimates without changing the pattern. In this selected hospital-based linked-record cohort of pregnancies reaching ≥ 28 completed weeks, IPIs < 18 months, particularly < 12 months, were associated with higher risk of the composite adverse perinatal outcome. The findings identify short IPI as a clinically relevant marker in this setting but do not establish causality and should be interpreted in light of exposure misclassification, residual socioeconomic confounding, selection related to linked-record eligibility, and incomplete ascertainment of out-of-hospital deaths.