Incidence and risk factors of infertility among couples who desire a first and second child in Shanghai, China: a facility-based prospective cohort study.

Background: With the implementation of the two-child policy in China, more couples have expressed the desire to have another child. We conducted this study to evaluate the incidence of infertility and risk factors in couples intending to have a first and second child. Methods: From 2013 to 2017, a prospective cohort study was conducted at the pre-pregnancy center of the International Peace Maternal and Child Health Hospital. The participants were selected by screening and random sampling couples who came to the pre-pregnancy center. Data regarding patient sociodemographic characteristics, reproductive and gynecological history, male disease history, and laboratory and imaging examination results were collected. Couples were followed up every 3 months until pregnancy or for 12 months, whichever came first. Multi-factor logistic regression was used to analyze risk factors for infertility. Adjusted odds ratios (aORs) and corresponding 95% confidence intervals (CIs) were calculated and adjusted for potential confounding factors. Results: The overall infertility incidence was 16.95% (369/2177). The infertility incidence of "first child intention" and "second child intention" was 19.30% (355/1839) and 4.14% (14/338), respectively. This study found great differences in both infertility rate (P < 0.001) and risk factors between the two groups. Risk factors for "first child intention" infertility included advanced age (> 35 years) (aOR = 1.70, 95% CI 1.27–2.28), abnormal body mass index (BMI) (aOR = 1.58, 95% CI 1.31–6.26), longer menstrual periods (aOR = 4.47, 95% CI 2.25–8.88), endometrial polyps (aOR = 2.52, 95% CI 1.28–4.97), polycystic ovarian syndrome (PCOS) (aOR = 6.72, 95% CI 1.79–7.39), salpingostomy (aOR = 3.44, 95% CI 1.68–7.07), and history of mycoplasma (aOR = 1.54, 95% CI 1.09–2.40). However, in the "second child intention" group, clinical risk factors slightly differed and included leiomyoma (aOR = 5.60, 95% CI 1.06–29.76), and higher age (> 40 years) (aOR = 7.36, 95% CI 1.01–53.84). Conclusion: The overall infertility rate in Shanghai is similar to that of other large cities in China. Marriage at advanced ages has become increasingly common. As such, the government must consider subsidies to encourage childbirth at childbearing ages, which can improve fertility levels. Plain Language Summary: Infertility is defined as pregnancy failure after at least 12 months of regular unprotected sexual intercourse. Few researchers have investigated the infertility rate in Shanghai in the past 15 years, and little attention has been paid to the infertility of couples hoping to have a second child. We conducted a prospective cohort study in Shanghai to evaluate infertility incidence and risk factors in couples intending to have a first or second child. The investigators administered a questionnaire survey to the participants and followed them for 1 year. Finally, 1839 couples intending to have a first child and 338 couples intending to have a second child were included in this study. The overall infertility incidence was 16.95% (369/2177). However, the infertility incidence of the "first child intention" and "second child intention" groups was 19.30% (355/1839) and 4.14% (14/338), respectively. Risk factors for "first child intention" infertility included advanced age (> 35 years), abnormal body mass index (BMI), longer menstrual periods, endometrial polyps, polycystic ovarian syndrome (PCOS), salpingostomy, and history of mycoplasma; in the "second child intention" group, clinical risk factors slightly differed and included leiomyoma and advanced age (> 40 years). Since studies have shown large differences in infertility risk factors between the two groups, early and targeted intervention for couples in different high-risk groups can help reduce infertility. [ABSTRACT FROM AUTHOR]