Results
Background characteristics of study
participants
A total of 18,045 women who delivered a live birth between 12 and 24
months immediately preceding were interviewed for the present study. Of
these, 6005, 6010, and 6030 were from the eastern, central, and western
regions of China, respectively. Participants ranged in age from 16 to 50
years, with a mean age of 29.9 ± 4.6 years. More young mothers (aged
20–24) were interviewed in the western (15%) region relative to the
eastern (9%) and central (7%) regions. Less than half (48%) of the
participants possessed an undergraduate education, about 22% had
completed high school, and 22% had finished middle school. There were
more less-educated women (middle school or below) in the western (33%)
region than in the eastern (23%) or central (18%) regions. Han
nationality accounted for 88% of the study participants, although the
proportion of minorities was significantly higher in the western (12%)
region relative to the eastern and central regions (5%). Nearly half
(48%) of all participants were interviewed during the 13–18 months
postpartum; this proportion was higher in the eastern (52%) region
compared with the central (44%) and western (48%) regions. Baseline
demographics and characteristics of participants are shown in
supplementary Table S1.
Contraceptive rates, unmet need, and modifications in
contraceptive method use during the first 24months
postpartum
The cumulative 6-,12-, and 24-month contraception rates for participants
using any method were 73.9% (95% CI 73.3-74.5), 85.7% (95% CI
85.2-86.2), and 86.8% (95% CI 86.3-87.3), respectively; while the
rates for modern methods were 62.7% (95% CI 62.0-63.4), 72.4% (95%
CI 71.8-73.1), and 73.2% (95% CI 72.6-73.9), respectively. Among women
who resumed sexual intercourse after childbirth, the 6-, 12-, and
24-month values for unmet need for postpartum contraception were 28.7%
(95% CI 28.0-29.4), 25.6% (95% CI 25.0-26.2) and 23.8% (95% CI
23.2-24.4), respectively. The level of contraceptive use was highest in
the west (6-24 months: 77.8-88.6%) , followed by the east (6-24 months:
72.6-87.7%), and lowest in the central region (6-24 months:
71.4-84.0%) during the 24 months postpartum. In contrast, the
percentage of unmet need for postpartum contraception was highest in the
central region (6-24 months: 30.3-25.5%) and lowest in the east (6-24
months: 27.2-22.4%). (see Supplementary material, Table S2).
Condoms were dominant postpartum contraceptive method initially used
after childbirth, accounting for approximately 2/3 of study
participants, followed by traditional methods (14%), IUDs (2%), and
hormonal methods (1%). More than 10% (12%) of participants did not
use any methods. The variety of methods for first choice showed a
similar pattern betweens regions. (see Supplementary material, Table
S3).
A considerable number of initial contraceptive users changed their first
choices to current methods. Of the 12,097 initial condom users, 10%
switched to IUDs, 2% used traditional methods, and 4% became
non-users; approximately 46% of traditional-method users converted to
condoms, 13% changed to IUDs, and 8% became non-users; 7% of users
replaced IUDs with condoms, 4% removed IUDs and became non-method
users; 30% of combined oral contraceptive (COC) users changed to
condoms, 12% turned to IUDs, and 3% to traditional methods. More than
half (52%) of emergency contraceptive users turned to condom use and
19% to IUDs. (see Supplementary material, Table S4).
Pregnancy and unintended pregnancy during the first 24
months
postpartum
Our study encompassed a total of 2186 pregnancies after index births. Of
these, 1693 (77%) were unintended. More than half (52%, 1141) of the
pregnancies were conceived within the first 12 months after delivery,
and 83% (949/1141) of these were unintended.
Results of life-table analyses showed that the overall cumulative 6-,
12-, and 24-month pregnancy rates after childbirth were 1.7%, 6.3%,
and 18.5%, respectively. The rates were 1.5%, 5.6%, and 15.5% in the
east; 1.1%, 5.0%, and 17.8% in the central region; and 2.3%, 8.4%,
and 21.8% in the west, respectively (Table 1). As shown in Figure 1,
the curve for the western region increased faster than that for the
other two regions. Our log-rank test results indicated that pregnancy
rate was significantly higher in the west than in either of the other
two regions during the first two years postpartum (allP <0.001), while the rates for the eastern and central
regions were essentially similar (P = 0.329).
The overall cumulative 6-,12-, and 24-month unintended pregnancy rates
were 1.4%, 5.3%, and 13.6%, respectively. The regional rates were
1.4%, 4.8%, and 11.8% in the east; 1.0%, 4.2%, and 13.3% in the
central region; and 2.0%, 6.9%, and 15.6 in the west, respectively
(Table 1). The curve reflecting the unintended pregnancy rate rose
faster in the west than in the other two regions during the 24 months
postpartum (Figure 2, log-rank test, P <0.001), and as
the lines for the eastern and central regions overlapped, we observed no
statistical difference in the rates between the latter two regions
during the 24 months after delivery (log-rank test, P =0.183).
Abortion during the first 24 months
postpartum
Of the 1141 pregnancies conceived within 12 months of a delivery, 708
(62%) ended in abortion, accounting for 75% (708/949) of unintended
pregnancies during the postpartum period. However, only 8.3% (16/192)
of the pregnancies not reported as unintended pregnancies ended in
abortion. By 24 months postpartum, 59% (1286/2186) of all pregnancies
and 76% (1286/1693) of unintended pregnancies ended in abortion. Only
10% (50/493) of the non-unintended pregnancies were terminated by
abortive procedures.
Results of life-table analyses showed that the overall cumulative 6-,
12-, and 24-month rates of induced abortion were 1.1%, 4.0%, and
10.8%, respectively (Table 1). In addition, the cumulative 6-, 12-, and
24-month unintended pregnancy rates were 1.0%, 4.0%, and 10.2% in the
east; 0.7%, 3.0%, and 10.0% in the central region; and 1.4%, 5.1%,
and 12.1% in the west, respectively.
The cumulative rate for induced abortions increased fastest in the west
and slowest in the central region during the 24 months postpartum
(Figure 3). Women in the west were significantly more likely to undergo
an abortion relative to their counterparts in the eastern (P =
0.008) and central regions (P <0.001), and women in the
east were significantly more likely to have a pregnancy terminated by
abortion compared to those in the west (P = 0.003) during the
first two years after childbirth.