Table 1 Characteristics of women who had pregnancies affected by NTDs or OFCs (cases) and women who delivered healthy infants (controls)
Characteristics | Controls (n = 858) | Cases | |||
|---|---|---|---|---|---|
NTDs (n = 622) | OFCs (n = 135) | ||||
n(%)a | n(%)a | p-Value | n(%)a | p-Value | |
Maternal age (years) | |||||
< 25 | 358(42.4) | 249(40.8) | 0.800 | 61(47.3) | 0.140 |
25–29 | 268 (31.7) | 196 (32.0) | 45 (34.9) | ||
≥30 | 219 (25.9) | 166 (27.2) | 23 (17.8) | ||
BMI (kg/m2) | |||||
< 18.5 | 53 (6.3) | 45 (7.5) | 0.002 | 11 (8.5) | 0.339 |
18.5–23.9 | 417 (49.8) | 350 (58.0) | 70 (53.8) | ||
≥ 24 | 368 (43.9) | 208 (34.5) | 49 (37.7) | ||
Ethnicity | |||||
Han | 853 (99.6) | 620 (99.8) | 1.000 | 135 (100) | 1.000 |
Other | 3 (0.4) | 1 (0.2) | 0 (0) | ||
Occupation | |||||
Farmer | 568 (66.9) | 420 (69.2) | 0.356 | 73 (54.1) | 0.004 |
Other | 281 (33.1) | 187 (30.8) | 62 (45.9) | ||
Education | |||||
Primary or lower | 51 (6.0) | 101 (16.3) | < 0.001 | 18 (13.5) | 0.002 |
Junior high | 656 (76.9) | 445 (71.8) | 87 (65.4) | ||
High school or above | 146 (17.1) | 74 (11.9) | 28 (21.1) | ||
Parity | |||||
Primiparas | 538 (62.8) | 345 (56.4) | 0.013 | 95 (70.9) | 0.069 |
Multiparas | 319 (37.2) | 267 (43.6) | 39 (29.1) | ||
History of pregnancy affected by birth defects | |||||
Yes | 18 (2.1) | 42 (6.8) | < 0.001 | 5 (3.7) | 0.360 |
No | 838 (97.9) | 573 (93.2) | 130 (96.3) | ||
Infant sex | |||||
Male | 404 (47.6) | 268 (43.9) | 0.153 | 84 (62.2) | 0.002 |
Female | 444 (52.4) | 343 (56.1) | 51 (37.8) | ||
Folic acid supplementation | |||||
Yes | 113 (13.7) | 65 (10.7) | 0.090 | 20 (14.4) | 0.690 |
No | 709 (86.3) | 540 (89.3) | 113 (85.6) | ||
Maternal smoking exposure | |||||
Yes | 491 (57.6) | 423 (68.6) | < 0.001 | 84 (62.2) | 0.315 |
No | 361 (42.4) | 194 (31.4) | 51 (37.8) | ||
Alcohol drinking | |||||
Yes | 5 (0.6) | 9 (1.4) | 0.107 | 4 (3.0) | 0.024 |
No | 848 (99.4) | 613 (98.4) | 131 (13.4) | ||
Season of conception | |||||
Spring | 202 (24.1) | 156 (25.4) | 0.657 | 36 (26.9) | 0.857 |
Summer | 206 (24.6) | 142 (23.2) | 29 (21.6) | ||
Autumn | 207 (24.7) | 164 (26.8) | 33 (24.6) | ||
Winter | 222 (26.5) | 151 (24.6) | 36 (26.9) | ||