Results in context
Researchers have previously provided different estimations of TTP from various kinds of studies with retrospective, prospective, or cross-sectional designs.(5, 9-13) Several results for both pregnant and nonpregnant women were obtained from these studies, which are comparable to the findings of our study. A population-based survey across Denmark, Germany, Poland, Italy, and Spain investigated 6,630 women aged 25–44 years and collected data on their time of unprotected intercourse either leading or not leading to pregnancy.(14) Among these women, 23.4% did not conceive within 12 months, and the highest proportion occurred in Poland (33.3%). Another cross-sectional study from South Africa collected data on TTP from the most recent pregnancy of 1,121 women aged 18–49 years, including women who conceived and women still attempting to conceive.(11) The percentage of women who were not pregnant after 3, 6, 12, and 24 months was 67%, 50%, 32%, and 17%, respectively. The TTP observed in our study was comparable to that previously described by prior studies—that is, 81.7%, 63.0%, 46.6%, 23.3%, and 14.4% of couples still would not have conceived at 3, 6, 12, 24, and 36 months, respectively.
Notably, 56% of women aged <35 years conceived within 1 year, and the percentage reached 80% within 2 years of initiating attempt. However, for women older than 35 years, the probability of natural conception was as low as 30% and 50% at 1 year and 2 years, respectively. Infertility has been demonstrated to be related to individual psychological burden, intimate partner violence, unsafe sexual behavior, social stigma and isolation, mental or other health implications, and even financial difficulty.(15, 16) Couples are suggested to seek medical help if they fail to conceive after 1 year of attempt. For women aged 35 years or older, the suggested attempt duration is 6 months before they are encouraged to receive evaluation or treatment.(17) From a public health perspective, it might be beneficial if they resort to intervention early. With the global development of assisted reproductive technology (ART), it is easier to receive treatment nowadays, and some institutes even routinely perform intra-cytoplasmic sperm injection for infertile couples.(18) As revealed in our results, women aged <35 years still have a high probability of achieving natural pregnancy within 2 years.
Under the circumstances of rapid societal development, pressures that couples commonly confront are unprecedented and could also affect their fecundity.(19) Additionally, the diagnosis of infertility imposes considerable spiritual burden. However, stress and anxiety concerning infertility are often overlooked and little time is left for couples to adjust.(20) Although ART has been hugely beneficial in treating infertility, ART might not be the only solution for young couples who cannot conceive within 1 year. Perhaps more attention and patience should be paid to couples’ mental health, and more of an effort could be made to help couples achieve natural pregnancy through addressing mental health issues first.
Compared with the analysis of risk factors associated with constructed measures of infertility, the analysis of TTP could explore related factors with better time sequences. Therefore, we also found related risk factors for impaired fecundity by using a Cox regression model. Consistent with the results of previous studies in the literature, age had a significant effect on couples’ TTP in our study. Furthermore, in our study, socioeconomic status such as educational level and household income was related to TTP: TTP was shorter in couples with higher educational attainment, which was mainly attributable to their healthier lifestyle(21) and successful use of preventive and curative care.(22) Results in our population revealed that high-income couples had longer TTPs compared with the low-income group. It was well established that high fertility was associated with poverty(23) and could be explained by the fact that high-income couples in China tend to postpone the timing of pregnancy and can experience induced abortion, which might increase their possibilities of suffering from infertility.(3) In our study, exposure to radioactive and toxic substances increased related TTP in men, which has been confirmed in lots of related literature of both human and animal species.(24, 25) Therefore, a safe work environment was said to be a key factor for normal male fertility.(26)