[Infertility prevalence in the city of Porto]

To determine the prevalence of infertility in Porto and to assess the association between infertility and women's year of birth and socioeconomic status.

In a cross-sectional study were evaluated in Porto, in 1999-2003, 1540 women aged 18-90 years. Structured face-to-face interviews comprising information on social, demographic, personal and family history, gynaecological and obstetric history, cognitive capacity and behavioural characteristics were performed. Gynaecological history included lifetime infertility. Primary infertility was defined as never being able to achieve a pregnancy after more than one year trying to conceive. Secondary infertility means that the woman has already conceived, but subsequently was unable, for at least a period of one year. Socioeconomic status was evaluated by education and job.

The prevalence of lifetime infertility was 12.0% (95% confidence interval: 10.4%-13.7%). The prevalence of primary infertility was 7.7% and secondary infertility was 3.8%. The prevalence of infertility was not significantly different according to women's year of birth, education or job. Infertility was significantly more frequent among married/cohabiting/widow/divorced women (13.9%) compared to single women (1.7%).

These findings do not confirm the increase of infertility with more recent birth cohorts. There appeared no association between infertility and socioeconomic status. It was found higher prevalence on married/cohabiting/widow/divorced women comparative to single group women, and these differences were statistically significant.