Maternal, pregnancy and neonatal outcomes in triplet pregnancies in Sweden - a nationwide cohort study.

Background: Triplet pregnancies carry a high risk of pregnancy-related complications. The primary aim of this study was to describe maternal, pregnancy, and neonatal outcomes in expectantly managed triplet pregnancies in Sweden. The secondary aim was to compare outcomes in expectantly managed triplet pregnancies with triplet pregnancies where fetal reduction had been performed with the only indication to reduce the number of fetuses.

Methods: Nationwide cohort study based on linkage of data from three national Swedish registers. Triplet pregnancies with delivery at gestational age ≥ 22⁺⁰ weeks between 2014 and 2019 were included.

Results: In the main cohort of expectantly managed triplet pregnancies (n = 106), 98% (312/318) of infants were liveborn with a mean gestational age at birth of 32⁺³ weeks and a mean birthweight of 1,726 g. Nine percent (n = 29) suffered from severe neonatal morbidity, and 4% (n = 12) died during the neonatal period. In the reduced cohort (n = 13 pregnancies), all infants were liveborn (n = 22). Mean gestational age at birth (36⁺⁰ weeks) and mean birthweight (2,444 g) were higher than in the expectantly managed cohort (P < 0.01 for both comparisons). There were no cases of severe neonatal morbidity (P = 0.24) or mortality (P = 1.00).

Conclusion: Overall neonatal survival from 22⁺⁰ weeks of gestation in expectantly managed triplet pregnancies in Sweden was high. Nine out of 10 infants did not suffer from severe neonatal morbidity. Fetal reduction was performed in only a very small number of cases and was associated with higher gestational age at birth and higher birth weight.