Main Findings
In this cross-sectional study of sampled couples aged 20–49 years, we described the TTP distribution via survival analysis. The mean ± SD for TTP in our study was 17.2 ± 22.7 months. Women aged 20–24 years had the highest percentage of pregnancy at 3, 6, 12, and 24 months. Approximately 56% and 80% of women aged <35 years conceived within 1 year and 2 years, respectively. Only about 30% and 50% of women older than 35 years conceived at 1 year and 2 years, respectively. In addition to the consecutive distribution of fecundity, we found several associated risk factors for TTP, including older age of couples, lower current BMI of women, lower educational attainment of women, higher annual household income, toxic exposure in men, shorter duration of cohabitation, longer menstrual cycle interval, history of abnormal pregnancy, and nullipara. To the best of our knowledge, our study is one of the first to indicate the TTP distribution in a representative Chinese population combined with cross-sectional and retrospective study designs.