Short Interpregnancy Intervals Are Linked to Elevated Perinatal Risks in Somalia

A retrospective cohort investigation conducted at a tertiary referral hospital in Mogadishu has found that short interpregnancy intervals are significantly associated with an elevated risk of composite adverse perinatal outcomes among women in Somalia. In the analyzed population, intervals under 18 months, and particularly those under 12 months, showed markedly higher rates of complications compared with an interpregnancy spacing of 18 to 23 months. Researchers observed that while short birth spacing is frequent and substantial barriers to maternal and newborn care persist in the region, rigorous empirical evidence regarding birth spacing outcomes has historically remained scarce.

The study evaluated a retrospective linked-pregnancy cohort spanning deliveries documented between January 1, 2019, and September 1, 2025. Researchers screened 12,686 hospital delivery records to assemble a precise cohort of 464 unique women, each contributing exactly one linked consecutive-pregnancy pair. Eligibility criteria required women to be aged 18 to 40 years, to have delivered a singleton index pregnancy at 28 or more completed weeks of gestation, and to have experienced an immediately preceding delivery at 28 or more weeks within the same facility. Inclusion also strictly required verifiable linked medical records tracking pregnancy chronology, gestational dating, the primary clinical outcome, and early neonatal vital status.

To measure birth spacing, investigators calculated the interpregnancy interval from the delivery date of the preceding infant to the estimated start of the index pregnancy, derived using last-menstrual-period-equivalent dating. The team categorized birth spacing into five distinct exposure groups: less than 6 months, 6 to 11 months, 12 to 17 months, 18 to 23 months, and 24 months or longer. The interval spanning 18 to 23 months served as the designated reference category across statistical models. The study’s primary composite endpoint comprised five distinct adverse perinatal events: preterm live birth between 28 weeks 0 days and 36 weeks 6 days, low birthweight, small for gestational age, stillbirth, or early neonatal death.

Across the entire cohort, the primary composite outcome occurred in 160 of the 464 index pregnancies, representing an overall occurrence rate of 34.5 percent. Complication frequencies differed substantially across the defined spacing intervals. The observed adverse outcome rates were 58.5 percent for intervals under 6 months, 67.9 percent for intervals between 6 and 11 months, and 39.2 percent for intervals between 12 and 17 months. In contrast, the reference category of 18 to 23 months exhibited an adverse outcome rate of 13.9 percent, while pregnancies conceived after an interval of 24 months or greater recorded a composite rate of 19.7 percent.

To account for confounding, investigators applied modified Poisson regression models to calculate adjusted risk ratios. In the primary statistical model, which adjusted for maternal demographic variables and reproductive history confounders, the adjusted risk ratio was 2.35 with a 95 percent confidence interval of 1.32 to 4.19 for intervals shorter than 6 months. For intervals between 6 and 11 months, the adjusted risk ratio peaked at 2.85 with a 95 percent confidence interval of 1.69 to 4.80. The 12 to 17 month interval yielded an adjusted risk ratio of 1.83 with a 95 percent confidence interval of 1.06 to 3.18, whereas intervals of 24 months or more showed an adjusted risk ratio of 1.36 with a 95 percent confidence interval of 0.78 to 2.39.

Researchers further quantified outcome probabilities through marginal standardization utilizing the primary model covariates. These standardized risk estimates were calculated as 44.8 percent for intervals under 6 months, 56.0 percent for 6 to 11 months, 33.6 percent for 12 to 17 months, 20.1 percent for the 18 to 23 month reference group, and 26.0 percent for intervals of 24 months or more. In secondary modeling, investigators developed a conditional framework that additionally accounted for antenatal care attendance and maternal anemia. Furthermore, a sensitivity analysis incorporating a plus 14-day conception-dating adjustment modestly attenuated the risk estimates without altering the overall observed pattern.

The study authors emphasized that while shorter interpregnancy intervals serve as a clinically relevant marker of perinatal vulnerability in this tertiary setting, the observational associations do not establish a causal mechanism. The findings must be interpreted alongside several key methodological constraints, including potential exposure misclassification from recall or dating methods, residual socioeconomic confounding, and selection pressures inherent in requiring linked hospital records across consecutive births. Furthermore, the analysis was subject to incomplete ascertainment regarding infant deaths occurring outside the hospital environment, underscoring the specific scope of this facility-based cohort reaching at least 28 completed weeks of gestation.

Subject of Research: Association between interpregnancy intervals and adverse perinatal outcomes in Somalia

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

Article References: Toplu, M. İ., Hassan, H. B., Yusuf, I. A., Aydoğdu, B. D., Eren, M., Batman, A., Özalp, M., & Mihmanlı, V. (2026). Interpregnancy interval and adverse perinatal outcomes in Somalia: a single-center retrospective linked-pregnancy cohort study. BMC Pregnancy and Childbirth. https://doi.org/10.1186/s12884-026-10128-x

Image Credits: AI Generated

DOI: 10.1186/s12884-026-10128-x

Keywords: interpregnancy interval, birth spacing, perinatal outcomes, preterm birth, low birthweight, small for gestational age, stillbirth, early neonatal death, Somalia, Mogadishu, maternal health, neonatal vital status, cohort study, modified Poisson regression, risk ratios, maternal anemia, antenatal care