Table 1 Baseline characteristics of 92,796 women who delivered singleton live births
Number of women | Frequency (%) | Gastroschisis (n = 9) | ||
|---|---|---|---|---|
Number of cases | Frequency (%) | |||
Pre-pregnancy body mass index | ||||
< 18.5 kg/m2 (underweight) | 15,034 | 16.2 | 2 | 0.01 |
18.5–24.9 kg/m2 (reference) | 67,774 | 73.1 | 4 | 0.01 |
≥ 25.0 kg/m2 (overweight) | 9864 | 10.6 | 2 | 0.02 |
Missing | 124 | 0.1 | 1 | |
Age at delivery (years) | ||||
< 20 | 854 | 0.9 | 0 | 0 |
20–29 | 33,955 | 36.6 | 2 | 0.01 |
30–39 | 53,683 | 57.9 | 7 | 0.01 |
≥ 40 | 4299 | 4.6 | 0 | 0 |
Missing | 5 | 0.0 | 0 | |
Occupation in early pregnancy | ||||
Administrative, managerial, professional, or engineering | 20,988 | 22.6 | 0 | 0 |
Clerical | 15,501 | 16.7 | 3 | 0.02 |
Sales and service | 20,118 | 21.7 | 3 | 0.01 |
Homemaker | 25,193 | 27.2 | 2 | 0.01 |
Others | 8965 | 9.7 | 0 | 0 |
Missing | 2031 | 2.2 | 1 | |
Smoking habits | ||||
Never smoked | 53,336 | 57.5 | 3 | 0.01 |
Ex-smoker or smoker during early pregnancy | 38,486 | 41.5 | 6 | 0.02 |
Missing | 974 | 1.1 | 0 | |
Alcohol consumption | ||||
Never drank | 31,681 | 34.1 | 5 | 0.02 |
Ex-drinker or drinker during early pregnancy | 60,231 | 64.9 | 4 | 0.01 |
Missing | 884 | 1.0 | 0 | |
Current history of diabetes or gestational diabetes | ||||
No | 89,871 | 96.9 | 9 | 0.01 |
Yes | 2925 | 3.2 | 0 | 0 |
Parity | ||||
0 | 40,420 | 43.6 | 3 | 0.01 |
≥ 1 | 51,968 | 56.0 | 5 | 0.01 |
Missing | 408 | 0.4 | 1 | |
Infertility treatment | ||||
No | 86,532 | 93.3 | 8 | 0.01 |
Yes | 6140 | 6.6 | 0 | 0 |
Missing | 124 | 0.1 | 1 | |
Routine use of folic acid supplement | ||||
No (< 4 times/week) | 66,172 | 71.3 | 5 | 0.01 |
Yes (≥ 4 times/week) | 24,548 | 26.5 | 3 | 0.01 |
Missing | 2076 | 2.2 | 1 | |
Week of pregnancy at delivery | ||||
< 37 | 4364 | 4.7 | 6 | 0.14 |
≥ 37 | 88,210 | 95.1 | 3 | 0.00 |
Missing | 222 | 0.2 | 0 | |
Infant sex | ||||
Male | 47,603 | 51.3 | 7 | 0.01 |
Female | 45,182 | 48.7 | 2 | 0.00 |
Unknown or missing | 11 | 0.0 | 0 | |