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)