Prevalence of infertility among nationally representative women in Japan: A cross-sectional survey using a two-stage...

According to the 2021 Japanese National Fertility Survey, more than one-third of couples expressed concerns about infertility. However, no study in Japan has estimated the prevalence of infertility according to the World Health Organization definition (12 months of infertility). This study aimed to estimate the prevalence of infertility based on this definition.

A cross-sectional study design.

The survey was conducted in 2024 using a two-stage stratified systematic sampling design (response rate: 40.0 %). Among 1200 women aged 25-49 years (total participants), 853 were married or cohabiting with a male partner (cohabiting participants). There were 35 women aged 25-44 years, at risk of pregnancy, and actively trying to conceive (current duration participants). Lifetime and period prevalence were estimated using direct (self-reported) and current duration methods.

Among cohabiting participants, the lifetime and period prevalence of infertility were 37.8 % (95 % confidence interval [CI]: 35.4 %-40.4 %) and 6.5 % (95 % CI: 5.1 %-8.4 %), respectively. Period prevalence among current duration participants was 23.1 % (95 % CI: 12.1 %-43.9 %). Help-seeking behaviour was reported by 51.1 % of those with lifetime infertility. Older age groups exhibited higher lifetime prevalence and lower period prevalence of infertility. Higher educational attainment was associated with lower lifetime and period prevalence of infertility and a higher help-seeking rate.

While period prevalence estimated using direct and current duration methods was consistent with international findings, lifetime prevalence estimated using direct method was higher, possibly due to older age distribution, delayed parenthood, shorter or ambiguous reproductive intention, and infrequent sexual activity.