Intrauterine fetal death of one twin of diamnionic twins is associated with adverse perinatal outcome of the co-twin.

Objective: To determine whether intrauterine fetal death (IUFD) of one twin of diamnionic twins after 22 weeks of gestation is associated with adverse perinatal outcome to the co-twin.

Method: A retrospective case-control study (n = 4070), including all twin births delivered between the years 1988 and 2010, was conducted. Perinatal outcome of the co-twin in diamnionic pregnancies complicated by IUFD were compared with the first twin from a pair of live-born diamnionic twins. A multiple logistic regression model was constructed to determine the association between IUFD of one twin and postpartum death (PPD) of the co-twin while controlling for confounders such as gestational age.

Results: Pregnancies complicated with IUFD of a co-twin (n = 116) had higher rates of adverse perinatal outcomes such as PPD (9.5% vs. 2.3%, p < 0.001), low Apgar scores (<7) at 1 and 5 min (30.2% vs. 10.6%, p < 0.001 and 6.9% vs. 1.8%, p < 0.001, respectively), lower birth weight (1953 ± 746 g vs. 2299 ± 559 g), and higher rates of preterm birth before 34 weeks of gestation (38.8% vs. 16.4%, p < 0.001). Using a multivariate analysis with PPD as the outcome variable, mortality was attributed to gestational age (adjusted OR = 0.58; 95% CI 0.5-0.6, p < 0.001) and not to the IUFD per se (adjusted OR = 1.3, 95% CI 0.5-3.3, p = 0.552).

Conclusion: Intrauterine fetal death of one twin (of diamnionic twins) is associated with adverse perinatal outcome of the co-twin mainly due to prematurity.