Associated factors for TTP
Cox regression calculations revealed factors that considerably impaired
the probability of pregnancy (Table 3). In an adjusted model, older
groups had significantly longer estimated TTP than the group aged 20–24
years. Women with lower educational attainment tended to have longer
TTPs than those with higher educational attainment (adjusted FOR=1.31,
95% CI: 1.04–1.64 for women with college and higher educational
level). Women without full-time work were more likely to become pregnant
than employed women (adjusted FOR=1.60, 95% CI: 1.48–1.73 for
unemployed women). As shown in Table 1, couples with a higher annual
household income had impaired probability of conception than couples
with a lower income (adjusted FOR=0.75, 95% CI: 0.67–0.84 for
households with an income of more than 20,000 RMB). With respect to
reproductive characteristics, couples who had a longer duration of
cohabitation (FOR=1.06, 95% CI:
1.05–1.07) or were multiparous (FOR=1.13, 95% CI: 1.02–1.25) had
shorter TTP than those who had a shorter duration of cohabitation or
were uniparous. Other factors that could potentially reduce the
probability of pregnancy included toxic exposure in men, longer
menstrual cycle interval, and history of abnormal pregnancy. All other
factors evaluated in our study did not have a statistically significant
influence on pregnancy rates.