# Associations of paternal age with offspring under-five mortality and perinatal outcomes: a cohort study using claims data in Taiwan

## TL;DR

This study explores how a father's age affects children's health outcomes, finding mixed results after accounting for family factors.

## Contribution

The study uses sibling comparisons to reduce confounding and finds nuanced associations between paternal age and offspring health.

## Key findings

- Older paternal age is linked to lower under-five mortality and better birth outcomes in some cases.
- Sibling comparisons show reduced risks of low birth weight and congenital defects with older fathers.
- However, older paternal age is associated with higher risks of premature birth and large for gestational age.

## Abstract

The causal relationship between advanced paternal age and offspring health is unclear, owing to familial confounders. This study examined the association of paternal age with offspring’s under-five mortality and perinatal outcomes, using sibling comparison analyses to account for familial confounding factors.

A nationwide birth cohort study was designed based on Taiwan’s single-payer compulsory National Health Insurance programme. Individuals born between 2001 and 2015 were included, resulting in 2454 104 live-born singletons. Among them, 1513 222 individuals had full sibling(s) who were included in the sibling-comparison analyses. Logistic regression analyses were used to evaluate the main study cohort whereas conditional logistic regressions were used in the sibling-comparison analyses.

In the main cohort, paternal age categories showed a U-shaped relationship with offspring’s under-five mortality in the crude analysis, which attenuated towards the null hypothesis after accounting for the measured potential confounders. There was an increased risk of premature birth (gestational age <37 weeks), low birth weight (<2500 g), large for gestational age (90th percentile) and low 5 min Apgar Score (<7) in individuals with a paternal age of >35 years. Sibling-comparison analyses that accounted for unmeasured familial time-invariant confounders showed that younger siblings with older paternal age had a lower risk of under-five mortality, low birth weight, small for gestational age (10th percentile), congenital defects and low 5 min Apgar Score, and a higher risk of premature birth and large for gestational age.

Children with older fathers had lower risks of under-five mortality, low birth weight, small for gestational age, congenital defects and low 5 min Apgar Score.