Maternal BMI in Twin Pregnancies and Impact on Neonatal Outcomes in the Level I Unit: A Retrospective Cohort Study.

Objective: With maternal obesity rates and twin pregnancies on the rise, the aim of this study was to assess the impact of pre-pregnancy or first trimester BMI on short-term neonatal morbidities in twins admitted to a level I unit.

Methods: This retrospective single-centre cohort study was conducted on twins born between January 1, 2010 and December 31, 2013 and admitted to the level I unit at Mount Sinai Hospital in Toronto, Ontario. Twin pairs were categorized according to maternal BMI: underweight (<18.5 kg/m), normal weight (18.5-24.9 kg/m), overweight (25.0-29.9 kg/m), and obese (≥30 kg/m). The primary outcome was combined neonatal morbidities of hypoglycemia and hyperbilirubinemia. The secondary outcome was length of hospital stay. All outcomes were compared between twins in various BMI groups, and data were analyzed using the chi-square test or ANOVA (Canadian Task Force Classification II-2).

Results: Data on 700 neonates born to 350 women were analyzed. Baseline maternal and neonatal characteristics were similar between the groups, except for a statistically significantly higher incidence of maternal hypertension (P < 0.02) and a trend towards increased gestational diabetes rates (P = 0.05) in women with overweight or obesity compared with women with underweight or normal weight. No association was noted between maternal BMI and occurrence of neonatal hypoglycemia, hyperbilirubinemia, and length of stay in either twin pair (P > 0.05) CONCLUSION: Maternal BMI had no detectable effect on neonatal morbidities and length of stay in twins admitted to the level I unit in the study centre.