Estimation of TTP
Figure 2A shows
the
estimated survival function of TTP up to 120 months, which corresponded
to the elapsed time from stopping contraception to confirmation of
pregnancy or until the time of the investigation in both populations of
Groups 1 and
2.
The mean ± SD for TTP in our study was
17.2 ± 22.7, with a median duration
of 9 months and 25–75th percentiles of 3–20
months. The estimated proportion of
couples who had conceived was 18.3% (n=1,447) at 3 months, 37.0%
(n=2,919) at 6 months, 53.4%
(n=4,216) at 12 months, 76.7%
(n=6,047) at 24 months, and 85.6%
(n=6,753) at 36 months (Table 2). Additionally, we represented different
age patterns in women with the same method (Figure 2B). A similar
scenario was also presented for the population in Group 1 (Figure 2C and
Figure 2D). As can be drawn from the diagram, related curves dropped
more slowly, with visible ≥30-year differences in age among subgroups.
Furthermore, we estimated the proportions of TTP at 3, 6, 12, 24, and 36
months among different age populations (Table 2).
Women aged 20–24 years had the
highest percentage of pregnancy at 3, 6, 12, and 24 months (23.9%,
42.5%, 58.5%, and 80.4%, respectively). Additionally, 55.8%
(3,413/6,116) and 79.9% (4,885/6,116) of women aged <35 years
conceived within 1 year and 2 years, respectively, and the percentage
increased by only 8.4% (5,399/6116, 88.3%) in the third year. However,
only 30.6% (186/607) and 50.6% (307/607) of women aged ≥35 years
conceived at 1 year and 2 years, respectively.