Parental Age Over 25 Years at Delivery Linked to Allergic Disease Risk Increase

The age of parents at the time of delivery being ≥25 years is a risk factor for most childhood allergic diseases, according to recent findings, with allergic disease risk in patients with older parents being higher for each condition excluding drug allergy.1

These findings and others were the result of a recent analysis conducted in China by Ye Zhang, from the School of Public Health at Shanghai Jiao Tong University School of Medicine. Zhang and colleagues sought to examine the association between age at delivery and allergic disease development, given the rising age of many parents and the notable prevalence increases observed for childhood allergic conditions.

The research team highlighted that prior data had demonstrated that breastfeeding for over 6 months had the potential to modify the negative impact of neonatal and familial risk factors on development of allergic conditions during one’s childhood.2

“Given that knowledge gaps remain in research on the effect of parental age at delivery on childhood allergic diseases, our large population-based epidemiological study would further explore their association comprehensively and examine whether breastfeeding duration affects the associations,” Zhang et al. wrote.1

Trial Design Details

The investigative team designed their research, titled the Shanghai Children Allergy Study, to assess the distribution and characteristics of allergic conditions among children located within the city of Shanghai. Their study implemented a cross-sectional approach and was carried out between April - June 2019.

The team used a multi-stage, stratified random sampling method, randomly selecting 7 out of 9 urban districts and 6 out of 8 suburban or rural districts to recruit trial participants from primary schools and kindergartens. As these schools are featured in Shanghai's predominantly public education system, a representative population sample was ensured.

By the recruitment process’s conclusion, 15,976 children were involved by the researchers as subjects. For the purposes of evaluating the prevalence of different types of allergic conditions, the investigators implemented the International Study of Asthma and Allergy in Children (ISAAC) questionnaire.

This survey tool was designed to examine the existence of asthma, allergic rhinitis, drug allergies, food allergies, urticaria, and eczema.

The research team also gathered allergen testing information through the use of parental responses to various inquiries. The team determined the age of parents at the time of their childrens’ births through birth dates and categorized them into 3 cohorts.

Duration of parental breastfeeding was divided by the investigators into 2 categories: exclusive breastfeeding for up to 6 months, and breastfeeding past 6 months with exclusive breastfeeding for a minimum of 6 months. They utilized multivariate logistic regression models to determine any links between age of caregivers, breastfeeding times, and the risk of allergic conditions.

Findings on Allergic Disease Risk

After their analysis, the investigators reported that the rates of disease prevalence for asthma, allergic rhinitis, food allergy, drug allergy, urticaria, and eczema were shown to be 14.2%, 21.2%, 8.7%, 3.9%, 15.6%, and 35.5%, respectively. They added that a link was identified between parental age of 25 years or older during a child’s delivery and risk increases for these allergic diseases.

Specifically, it was noted that paternal age exerted a stronger influence over allergy development. The research team further noted that when both parents were aged 25 years or older, the allergic conditions’ odds ratios (OR) had a range between 1.266 - 1.541, with all P-values < .05 except for drug allergy.

They added, however, that maternal breastfeeding past the 6-month mark had an inverse correlation with the development of allergies. It was also shown to have mitigated the spike in risk associated with older parental age. The investigators’ sensitivity tests and stratified analyses were noted as having further validated these data.

“The present study, for the first time, identified a joint association of parental age at delivery with four allergic diseases,” they wrote. “The only study that jointly analyzed parental age was based on 10,141 Korean children, which did not observe a combining association between parental age and atopic dermatitis. However, it was found that paternal age was more strongly associated with childhood allergic disease which corroborates our finding.”1

References

1. Zhang Y, Lu R, Chen Y, et al. The association of parental age at delivery with childhood allergic disease and the modified effect of breastfeeding. Pediatr Allergy Immunol. 2025; 36:e70025. doi:10.1111/pai.70025.
2. Hu Y, Chen Y, Liu S, et al. Breastfeeding duration modified the effects of neonatal and familial risk factors on childhood asthma and allergy: a population-based study. Respir Res. 2021; 22(1): 41. doi:10.1186/s12931-021-01644-9.