ADULTS born to parents who took longer to conceive may face a higher risk of infertility themselves, according to findings from a Danish cohort study investigating potential intergenerational patterns of reproductive health.1
The study also found that a maternal history of infertility was linked to a greater likelihood of infertility in both sons and daughters.1
Infertility is defined by the WHO as the failure to achieve a pregnancy after 12 or more months of regular unprotected sexual intercourse and is said to affect approximately one in six people of reproductive age worldwide during their lifetime.2
Infertility can have substantial social and psychological consequences. Women often bear a disproportionate burden of the stigma, emotional distress and relationship difficulties associated with infertility, regardless of whether they are the source of the fertility problem.2
Delayed Conception May Have Long-Term Implications
To investigate whether parental fertility challenges may extend to the next generation, researchers analysed data from 11,144 adults born to women participating in the Danish Health Habits for Two cohort between 1984 and 1987.1
Parental time to pregnancy (TTP) was reported by mothers during pregnancy and categorised as 1-6 months, 7-12 months or more than 12 months. Maternal infertility history was defined as either self-reported infertility examination or treatment, or a registered infertility diagnosis before the index pregnancy.
Infertility in offspring was identified using nationwide registry data and defined as either receiving an ICD-10 infertility diagnosis or undergoing assisted reproductive technology treatment, either personally or through a partner.
Stronger Associations Observed Among Daughters
Among sons, parental TTP of more than 12 months corresponded to a higher risk of infertility in adulthood (HR 1.25; 95% CI 0.92-1.71), while a TTP of 7-12 months showed no increase in risk (HR 1.00; 95% CI 0.66-1.50).1 Dose-response analyses suggested a modest trend towards increasing infertility risk with longer parental TTP (HR 1.10; 95% CI 0.95-1.29).1
For daughters, the relationship was more consistent. Those born to parents with a TTP of 7-12 months had a 43% higher risk of infertility (HR 1.43; 95% CI 1.06-1.94), while those whose parents took more than 12 months to conceive had a 41% higher risk (HR 1.41; 95% CI 1.11-1.79).1 A dose-response trend was also observed among daughters (HR 1.20; 95% CI 1.07-1.35).1
Maternal Infertility History Also Increased Offspring Risk
A maternal history of infertility was linked to a greater likelihood of infertility in both male and female offspring.1 Sons whose mothers had a history of infertility had an 81% higher risk of infertility (HR 1.81; 95% CI 1.26-2.59), while daughters had a 49% higher risk (HR 1.49; 95% CI 1.10-2.01).
Intergenerational Fertility
The findings suggest that reduced fecundity and infertility may, in part, extend across generations.1 However, the authors emphasised that the observational study cannot establish causality and that further research is needed to replicate the results and clarify the mechanisms involved.1
An additional limitation is that infertility history was only assessed for mothers.1 Although prolonged TTP may reflect fertility difficulties affecting either partner, the study did not include a specific measure of paternal infertility history. Consequently, the relative contributions of maternal and paternal factors to infertility risk in offspring could not be determined.1
Future studies should explore the biological, genetic and environmental pathways that may underlie the observed associations and help explain how fertility challenges may be transmitted across generations.1
References
- Stokholm MV et al. Intergenerational fecundity and infertility: a cohort study. Fertil Steril. 2026;DOI:10.1016/j.fertnstert.2026.06.018.
- World Health Organization (WHO). Infertility. Available at: https://www.who.int/news-room/fact-sheets/detail/infertility. Last accessed 17 June 2026.
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