# Grandmaternal Obesity and Risks of Birth Asphyxia‐Related Complications in Grand‐Offspring: A Countrywide Three‐Generation Study

## TL;DR

Grandmothers' obesity during pregnancy is linked to higher risks of birth complications in their grandchildren, even after accounting for family factors.

## Contribution

This study shows that grandmaternal obesity increases birth asphyxia risks in grandchildren, independent of shared familial influences.

## Key findings

- Maternal grandmaternal obesity increases the risk of low Apgar scores and neonatal seizures in grandchildren.
- Paternal grandmaternal obesity is associated with increased risk of neonatal seizures.
- Maternal obesity explains less than 25% of the observed associations with maternal grandmaternal obesity.

## Abstract

We investigated the associations of grandmaternal early pregnancy BMI with grand‐offspring risks of birth asphyxia‐related complications.

In a nationwide three‐generation Swedish cohort, we estimated adjusted relative risks (RRs) of Apgar score 0–3 at 5 min and neonatal seizures for categories of grandmaternal BMI among 315,461 maternal and 203,522 paternal singleton live‐born grand‐offspring. To address unmeasured confounding by shared familial factors, we used the parental full sisters' BMI as a negative control exposure. In the maternal line, we assessed whether associations with grandmaternal obesity were mediated through maternal obesity.

Compared with normal maternal grandmaternal BMI, RRs (95% CI) of low Apgar score were, respectively, 1.29 (1.06, 1.57) and 1.53 (1.03, 2.28) for overweight (BMI 25.0 to 29.9) and obesity (BMI ≥ 30.0). For neonatal seizures, the corresponding RRs (95% CI) were 1.32 (1.05, 1.66) and 1.81 (1.17, 2.79). Maternal sisters' BMI was unrelated to both outcomes. Maternal obesity mediated < 25% of the associations with maternal grandmaternal obesity. Paternal grandmaternal obesity was related to an increased risk of neonatal seizures; paternal sisters' BMI was unrelated to this outcome.

Grandmaternal overweight and obesity are related to increased risks of severe birth asphyxia‐related complications in grand‐offspring, independent of unmeasured shared familial factors.