Effect of paternal body mass index on neonatal outcomes of singletons after frozen-thawed embryo transfer cycles: analysis of 7,908 singleton newborns

Abstract

Objective: To investigate the effect of paternal body mass index (BMI) on neonatal outcomes of singletons after frozen-thawed embryo transfer (FET) cycles.

Design: Retrospective cohort study.

Setting: Tertiary-care academic medical center.

Patient(s): A total of 7,908 singleton newborns were divided into four categories based on their paternal BMI: 284 (3.6%) infants were in the paternal underweight category, 4,678 (59.2%) infants were in the paternal normal weight category, 2,585 (32.7%) infants were in the paternal overweight category, and 361 (4.6%) infants were in the paternal obesity category. In addition, we included only infants of women with normal BMI (18.5 kg/m² ≤ BMI < 25 kg/m²).

Intervention(s): None.

Main outcome measure(s): Neonatal outcomes.

Result(s): The rates of large for gestational age (LGA) infants were significantly higher among those in the paternal overweight and obesity categories than those in the paternal underweight categories. The rates of very LGA were higher among infants in the paternal overweight categories and lower among infants in the paternal underweight categories than the rates in normal controls. The rates of fetal macrosomia were higher among infants in the paternal overweight categories than among infants in the paternal normal weight categories. Compared with normal controls, Z-scores (gestational age- and sex-adjusted birthweight) were significantly higher among the infants in the paternal overweight and paternal obesity categories and significantly lower among the infants in the paternal underweight categories. A positive association was observed in a multiple linear regression model between paternal BMI and newborn birthweights after adjustment for several potential confounders.

Conclusion(s): Paternal BMI had an independent impact on the birthweight of singletons born after FET cycles. Paternal overweight and paternal obesity were independent risk factors for having LGA infants after FET cycles. Furthermore, paternal overweight was an independent risk factor for fathering infants with macrosomia or very LGA infants after FET cycles.

Keywords: Paternal; birthweight; body mass index; fetal macrosomia; frozen-thawed embryo transfer; large for gestational age; neonatal outcomes.