|
Characteristics
|
2013
|
2014
|
2015
|
2016
|
2017
|
2018
|
|---|
|
N
|
1,360,384
|
1,813,753
|
1,552,952
|
1,706,939
|
1,709,637
|
1,254,380
|
|
Age
|
|
20–
|
449,607 (33.1)
|
482,363 (26.6)
|
391,365 (25.2)
|
350,263 (20.5)
|
283,488 (16.6)
|
205,376 (16.4)
|
|
25–
|
648,870 (47.7)
|
948,058 (52.3)
|
818,991 (52.7)
|
884,704 (51.8)
|
770,323 (45.1)
|
563,423 (44.9)
|
|
30–
|
199,323 (14.7)
|
305,331 (16.8)
|
257,309 (16.6)
|
339,758 (19.9)
|
419,649 (24.6)
|
337,983 (26.9)
|
|
≥ 35
|
62,584 (4.6)
|
78,001 (4.3)
|
85,287 (5.5)
|
132,214 (7.8)
|
236,177 (13.8)
|
147,598 (11.8)
|
|
Higher education
|
|
Yes
|
436,700 (32.1)
|
625,611 (34.5)
|
573,043 (36.9)
|
708,332 (41.5)
|
715,633 (41.9)
|
581,466 (46.4)
|
|
No
|
891,977 (65.6)
|
1,134,400 (62.5)
|
927,246 (59.7)
|
926,811 (54.3)
|
913,797 (53.5)
|
600,435 (47.9)
|
|
NA
|
31,707 (2.3)
|
53,742 (3.0)
|
52,663 (3.4)
|
71,796 (4.2)
|
80,207 (4.7)
|
72,479 (5.8)
|
|
BMI
|
|
Underweight
|
191,759 (14.1)
|
267,236 (14.7)
|
227,708 (14.7)
|
232,675 (13.6)
|
209,234 (12.2)
|
159,800 (12.7)
|
|
Normal weight
|
876,038 (64.4)
|
1,147,895 (63.3)
|
979,551 (63.1)
|
1,051,466 (61.6)
|
1,026,015 (60.0)
|
750,469 (59.8)
|
|
Overweight
|
169,411 (12.4)
|
228,695 (12.6)
|
200,350 (12.9)
|
234,272 (13.7)
|
255,224 (14.9)
|
183,551 (14.6)
|
|
Obese
|
102,921 (7.6)
|
153,108 (8.4)
|
133,190 (8.6)
|
176,100 (10.3)
|
207,396 (12.1)
|
152,599 (12.2)
|
|
NA
|
20,255 (1.5)
|
16,819 (0.9)
|
12,153 (0.8)
|
12,426 (0.7)
|
11,768 (0.7)
|
7961 (0.6)
|
|
Region
|
|
Northeast
|
17,087 (1.3)
|
21,362 (1.2)
|
12,880 (0.8)
|
17,295 (1.0)
|
16,405 (1.0)
|
13,631 (1.1)
|
|
North
|
70,111 (5.2)
|
132,151 (7.3)
|
83,421 (5.4)
|
113,796 (6.7)
|
99,505 (5.8)
|
72,659 (5.8)
|
|
Northwest
|
84,483 (6.2)
|
104,363 (5.8)
|
92,596 (6.0)
|
101,283 (5.9)
|
108,509 (6.4)
|
88,936 (7.1)
|
|
East
|
254,361 (18.7)
|
479,177 (26.4)
|
339,419 (21.9)
|
414,585 (24.3)
|
423,651 (24.8)
|
316,769 (25.3)
|
|
Central
|
554,208 (40.7)
|
657,323 (36.2)
|
637,957 (41.1)
|
656,494 (38.5)
|
625,204 (36.6)
|
441,871 (35.2)
|
|
South
|
250,558 (18.4)
|
275,153 (15.2)
|
253,124 (16.3)
|
260,102 (15.2)
|
268,554 (15.7)
|
180,011 (14.4)
|
|
Southwest
|
129,576 (9.5)
|
144,224 (8.0)
|
133,555 (8.6)
|
143,384 (8.4)
|
167,809 (9.8)
|
140,503 (11.2)
|
|
Nationality
|
|
Han
|
1,242,454 (91.3)
|
1,662,843 (91.7)
|
1,412,724 (91.0)
|
1,562,677 (91.6)
|
1,556,050 (91.0)
|
1,129,277 (90.0)
|
|
Others
|
102,498 (7.5)
|
132,018 (7.3)
|
122,268 (7.9)
|
120,483 (7.1)
|
131,382 (7.7)
|
100,268 (8.0)
|
|
NA
|
15,432 (1.1)
|
18,892 (1.0)
|
17,960 (1.2)
|
23,779 (1.4)
|
22,205 (1.3)
|
24,835 (2.0)
|
|
Adverse pregnancy outcomes in previous deliveries
|
|
Yes
|
224,699 (16.5)
|
298,746 (16.5)
|
241,003 (15.5)
|
284,002 (16.6)
|
337,703 (19.8)
|
253,686 (20.2)
|
|
No
|
1,124,249 (82.6)
|
1,505,067 (83.0)
|
1,302,460 (83.9)
|
1,414,285 (82.9)
|
1,363,499 (79.8)
|
994,880 (79.3)
|
|
NA
|
11,436 (0.8)
|
9940 (0.6)
|
9489 (0.6)
|
8652 (0.5)
|
8435 (0.5)
|
5814 (0.5)
|
|
Parity
|
|
Primipara
|
1,004,419 (73.8)
|
1,254,131 (69.2)
|
1,036,872 (66.8)
|
1,026,506 (60.1)
|
800,238 (46.8)
|
610,610 (48.7)
|
|
Multipara
|
343,741 (25.3)
|
548,999 (30.3)
|
506,195 (32.6)
|
671,455 (39.3)
|
900,763 (52.7)
|
637,945 (50.9)
|
|
NA
|
12,224 (0.9)
|
10,623 (0.6)
|
9885 (0.6)
|
8978 (0.5)
|
8636 (0.5)
|
5825 (0.5)
|
|
Full-term births
|
|
Yes
|
1,234,240 (90.7)
|
1,659,942 (91.5)
|
1,441,070 (92.8)
|
1,593,940 (93.4)
|
1,629,940 (95.3)
|
1,216,586 (97.0)
|
|
No
|
126,143 (9.3)
|
153,809 (8.5)
|
111,882 (7.2)
|
112,999 (6.6)
|
79,696 (4.7)
|
37,794 (3.0)
|
|
NA
|
1 (0)
|
2 (0)
|
0 (0)
|
0 (0)
|
1 (0)
|
0 (0)
|
|
Number of foetus
|
|
Singleton
|
1,352,364 (99.4)
|
1,802,094 (99.4)
|
1,543,985 (99.4)
|
1,697,149 (99.4)
|
1,700,026 (99.4)
|
1,246,359 (99.4)
|
|
Multiple
|
8019 (0.6)
|
11,657 (0.6)
|
8967 (0.6)
|
9790 (0.6)
|
9602 (0.6)
|
8021 (0.6)
|
|
NA
|
1 (0)
|
2 (0)
|
0 (0)
|
0 (0)
|
9 (0)
|
0 (0)
|
- Data are n (%). NA not available, BMI body mass index. BMI was calculated using weight/height2 (kg/m2). BMI < 18.5 was considered underweight, BMI ≥ 18.5 and < 24 were considered normal, BMI ≥ 24 and < 28 were considered overweight, and BMI ≥ 28 was considered obese according to the Chinese population standards. Higher education level was defined as senior high school, college, or postgraduate. Primiparity and multiparity were defined as parity of 0 and ≥ 1, respectively
