Perinatal Death in Triplets by Gestational Age: A Retrospective Cohort from Two Tertiary Hospitals

Abstract This study aimed to describe a contemporary cohort of triplet pregnancies from two tertiary centers in a middle-income country and evaluate the association between gestational age (GA) at birth and perinatal death. We developed and internally validated a GA-based risk model. Retrospective cohort from two tertiary hospitals (2015–2024). The unit of analysis was the fetus/neonate, with cluster-robust standard errors at the mother level. Primary outcome: Perinatal death (stillbirth ≥230/7 weeks or neonatal death ≤28 days). GA was modeled with logistic regression using restricted cubic splines; Firth penalization addressed separation where applicable. Internal validation used 200 bootstrap resamples. The cohort included 150 neonates; perinatal death occurred in 23 (15.4%). Median GA was 33 (31–34) weeks overall, 34.0 (32.0–34.0) in survivors, and 25.0 (24.0–28.0) in perinatal deaths. In the adjusted spline model, GA was the dominant predictor (overall Wald χ2 = 1,473.66, df = 3, p < 0.001; non-linearity χ2 = 424.92, df = 2, p < 0.001), while severe preeclampsia was not significant (χ2 = 0.10, p = 0.750). The category-based Firth model showed markedly elevated odds of perinatal death at earlier gestations versus ≥34 weeks: