Paternal overweight, obesity contribute to LGA risk after frozen embryo transfer

A high body mass index (BMI) among fathers appears to be a risk factor for a large for gestational age (LGA) outcome after frozen embryo transfer (FET), according to a study.

Researchers looked at 7,908 singleton newborns, among whom 284 (3.6 percent) had paternal BMI in the underweight category, 4,678 (59.2 percent) in the normal category, 2,585 (32.7 percent) in the overweight category, and 361 (4.6 percent) in the obesity category.  

The mean paternal BMI was 24.12 kg/m². Men with normal weight were slightly older (33.86 5.29 years) than those who were underweight but were slightly younger than those in the higher BMI categories. Men who were overweight or obese were more likely to be smokers than those who were of normal weight.

As earlier indicated, the proportion of LGA infants was significantly higher in the paternal overweight and obesity categories than in the paternal underweight category. The proportion was also higher in the paternal overweight category but lower in the paternal underweight category than in the normal-weight reference.

Meanwhile, the rates of foetal macrosomia were higher in the paternal overweight than in the normal weight category. Z-scores (gestational age- and sex-adjusted birthweight) were significantly higher among infants with overweight or obese fathers than among those whose fathers had normal weight.

Multiple linear regression model revealed a positive association between paternal BMI and newborn birthweight.

Additional studies with large sample sizes are needed to examine whether the differences in birthweight observed in the current study have implications for the risk of complications during the foetal and neonatal periods and many diseases in adulthood, the researchers said.