Adults born to parents who took longer to conceive may have a greater risk of developing cancer Infertility themselves, according to the results of a Danish cohort study investigating possible patterns of reproductive health between generations.1
The study also found that a maternal history of infertility is associated with an increased likelihood of infertility in both sons and daughters.1
The World Health Organization defines infertility as the failure to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse, and it is said to affect approximately one in six people of reproductive age worldwide during their lifetime.2
Infertility can have significant social and psychological consequences. Women often bear a disproportionate burden of stigma, emotional distress, and relationship difficulties associated with infertility, regardless of whether they are the source of the fertility problem.2
Delayed pregnancy may have long-term effects
To investigate whether parental fertility challenges might extend to the next generation, the researchers analyzed data from 11,144 adults born to women who participated in the Danish Two-Person Healthy Habits Group between 1984 and 1987.1
Parental time to pregnancy (TTP) was self-reported by mothers during pregnancy and was categorized as 1–6 months, 7–12 months or >12 months. Maternal infertility history was defined as either self-reported infertility screening or treatment, or an infertility diagnosis recorded before the index pregnancy.
Offspring infertility was determined using national registry data and was defined as either receiving an ICD-10 infertility diagnosis or undergoing assisted reproductive technology treatment, either personally or through a partner.
Stronger associations were observed among girls
Among offspring, paternal TTP of more than 12 months corresponded with a higher risk of infertility in adulthood (HR 1.25; 95% CI 0.92-1.71), whereas TTP of 7-12 months showed no increased risk (HR 1.00; 95% CI 0.66-1.50).1 Dose-response analyzes suggested a modest trend toward increased risk of infertility with a longer duration of parental TTP (HR 1.10; 95% CI 0.95-1.29).1
For girls, the relationship was more consistent. Those born to parents with 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 girls (HR 1.20; 95% CI 1.07-1.35).1
A history of maternal infertility also increased the offspring’s risk
A maternal history of infertility was associated with an increased likelihood of infertility in both males and females.1 Sons whose mothers had a history of infertility were 81% more likely to be infertile (hazard ratio 1.81; 95% confidence interval 1.26 to 2.59), while daughters were 49% more likely to be infertile (hazard ratio 1.49; 95% confidence interval 1.10 to 2.01).
Intergenerational fertility
The results suggest that fertility decline and infertility may partly extend across generations.1 However, the authors emphasized that an observational study cannot prove causality and that further research is needed to replicate the findings and elucidate the mechanisms involved.1
An additional limitation is that only maternal infertility history was assessed.1 Although prolonged TTP may reflect fertility difficulties affecting either partner, the study did not include a specific measure of paternal infertility history. Thus, the relative contributions of maternal and paternal factors to the risk of infertility in offspring cannot be determined.1
Future studies should explore biological, genetic, and environmental pathways that may underlie the observed associations and help explain how fertility challenges are transmitted across generations.1
References
- Stockholm MV et al. Intergenerational fertility and infertility: a cohort study. Sterile fertile. 2026;DOI:10.1016/j.fertnstert.2026.06.018.
- World Health Organization (WHO). Infertility. Available in: https://www.who.int/news-room/fact-sheets/detail/infertility. Last accessed June 17, 2026.
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