Figure legends
Figure 1. Flow charts of data according to eligibility for inclusion in the analysis (A) and process of collecting TTP from different participants (B).
Figure 2.Estimated survival function curve for TTP, corresponding to the elapsed time from stopping contraception to confirmation of pregnancy or end of pregnancy attempt in the overall population (A) and in Group 1 (C), and sorted by age of women (B) in the overall population and in Group 1 (D). Group 1 comprises women who had spontaneous pregnancy in the last year. Solid lines represent the curves for the estimated TTP censored at 120 months; dashed lines represent the 95% CIs around those curves.
Figure S1. Flow chart of multistage stratified cluster sampling strategy during participant selection.
In primary sampling units, the districts were categorized into two strata, representing high and low prevalence of infertility according to the prevalence in each district reported in 1988. Subsequently, two provinces/municipalities were randomly selected from each stratum. In secondary sampling units, townships in every province/municipality were ranked according to the local per capita gross domestic product and the number of women of childbearing age and were divided into nine strata. Subsequently, three townships were randomly selected from the highest, moderate, and lowest strata, respectively. In third sampling units, participants aged 20–49 years were identified in the selected townships; among these townships, every village/street was investigated as a unit.