Table 1.
Descriptive characteristics of the study sample.
| Variable |
Cases N = 97 (%) |
Control N = 194 (%) |
Chi square | P-value |
|---|---|---|---|---|
| Maternal pre-pregnancy BMI (kg/m2) | 3.191 | 0.354 | ||
| BMI <18.5 | 16 (16.5) | 37 (19.1) | ||
| 18.5–24 | 66 (68.0) | 138 (71.1) | ||
| BMI>24 | 15 (15.5) | 19 (9.8) | ||
| Maternal age (years, n) | 3.034 | 0.082 | ||
| n ≤ 35 | 80 (82.5) | 174 (89.7) | ||
| n > 35 | 17 (17.5) | 20 (10.3) | ||
| Chinese Han population | 2.445 | 0.118 | ||
| Yes | 90 (92.8) | 189 (97.4) | ||
| No | 7 (7.2) | 5 (2.6) | ||
| Educational level of pregnant women | 0.838 | 0.658 | ||
| Junior high or below | 34 (35.1) | 60 (30.9) | ||
| Technical secondary school, high school | 16 (16.5) | 29 (14.9) | ||
| Undergraduate college or above | 47 (48.4) | 105 (54.2) | ||
| Monthly household income (CNY, n) | 0.609 | 0.737 | ||
| n <3000 | 57 (58.8) | 107 (55.2) | ||
| 3,000–5,000 | 21 (21.6) | 50 (25.8) | ||
| n > 5000 | 19 (19.6) | 37 (19.0) | ||
| Work during pregnancy | 0.062 | 0.901 | ||
| Yes | 47 (48.5) | 91 (46.9) | ||
| No | 50 (51.5) | 103 (53.1) | ||
| Number of previous births (freq, n) | 3.567 | 0.168 | ||
| n = 0 | 68 (70.1) | 129 (66.5) | ||
| n = 1 | 21 (21.6) | 57 (29.4) | ||
| n ≥ 2 | 8 (8.3) | 8 (4.1) | ||
| Active/passive smoking during pregnancy | 0.293 | 0.628 | ||
| Yes | 19 (19.6) | 33 (17) | ||
| No | 78 (80.4) | 161 (83) | ||
| Alcohol consumption before pregnancy | 0.129 | 0.719 | ||
| Yes | 4 (4.1) | 5 (2.6) | ||
| No | 93 (95.9) | 189 (97.4) | ||
| Take vitamins or minerals before 13 weeks of pregnancy | 41.959 | <0.01 | ||
| Yes | 63 (64.9) | 137 (96.5) | ||
| No | 34 (35.1) | 5 (3.5) | ||
| Take vitamins or minerals between 14 and 26 weeks of pregnancy | 0.557 | 0.455 | ||
| Yes | 47 (48.5) | 103 (53.1) | ||
| No | 50 (51.5) | 91 (46.9) | ||
| Take vitamins or minerals after 27 weeks of pregnancy | 8.908 | <0.01 | ||
| Yes | 36 (37.1) | 108 (55.7) | ||
| No | 61 (62.9) | 86 (44.3) |