Table 1.
Maternal first-trimester folic acid supplementation and risk factor exposures for congenital heart disease case and control participants, GRCHD, China, 2004–2016.
| Maternal Exposures | Total | CHD Case, n (%) | Control, n (%) | OR (95% CI) * |
|---|---|---|---|---|
| Total | 15297 | 8379 | 6918 | - |
| Maternal FAS † | ||||
| Yes | 1877 (12.3) | 928 (11.1) | 949 (13.7) | 0.69 (0.62-0.76) |
| No | 13,420 (87.7) | 7451 (88.9) | 5969 (86.3) | 1.00 (ref) |
| Maternal disease † | ||||
| Fever | ||||
| Yes | 371 | 306 (3.7) | 65 (0.9) | 2.41 (1.81–3.20) |
| No | 14,926 | 8073 (96.3) | 6853 (99.1) | 1.00 (Ref) |
| Viral infection | ||||
| Yes | 1114 | 885 (10.6) | 229 (3.3) | 3.00 (2.56–3.52) |
| No | 14,183 | 7494 (89.4) | 6689 (96.7) | 1.00 (Ref) |
| Hypertension | ||||
| Yes | 148 | 115 (1.4) | 33 (0.5) | 2.37 (1.52–3.70) |
| No | 15,149 | 8264 (98.6) | 6885 (99.5) | 1.00 (Ref) |
| Threatened abortion | ||||
| Yes | 727 | 546 (6.5) | 181 (2.6) | 1.95 (1.62–2.35) |
| No | 14,567 | 7831 (93.5) | 6736 (97.4) | 1.00 (Ref) |
| Reproductive history | ||||
| Previous pregnancies with birth defects | ||||
| Yes | 106 | 95 (1.1) | 11 (0.2) | 6.55 (3.48–12.35) |
| No | 15,191 | 8284 (98.9) | 6907 (99.8) | 1.00 (Ref) |
| Spontaneous/elective abortion history | ||||
| Yes | 1037 | 644 (7.7) | 393 (5.7) | 1.28 (1.12–1.47) |
| No | 14,260 | 7735 (92.3) | 6525 (94.3) | 1.00 (Ref) |
| Maternal lifestyle and environmental factors | ||||
| Alcohol consumption † | ||||
| Yes | 87 | 65 (0.8) | 22 (0.3) | 1.65 (0.99–2.73) |
| No | 15,210 | 8314 (99.2) | 6896 (99.7) | 1.00 (Ref) |
| Active Smoking † | ||||
| Yes | 141 | 119 (1.4) | 22 (0.3) | 1.38 (0.82–2.32) |
| No | 15,156 | 8260 (98.6) | 6896 (99.7) | 1.00 (Ref) |
| Living in newly renovated home ‡ | ||||
| Yes | 392 | 317 (3.8) | 75 (1.1) | 2.28 (1.74–2.99) |
| No | 14,905 | 8062 (96.2) | 6843 (98.9) | 1.00 (Ref) |
| Residing within 50 m of a high traffic roadway ‡ | ||||
| Yes | 1721 | 1076 (12.8) | 645 (9.3) | 1.16 (1.04–1.30) |
| No | 13,576 | 7303 (87.2) | 6273 (90.7) | 1.00 (Ref) |
Abbreviations: OR, odds ratio; CHD, congenital heart disease; CI, confidence interval; FAS, folic acid supplementation; GRCHD, Guangdong Registry of Congenital Heart Disease; ref, reference category. * models adjusted for maternal sociodemographic factors (age, education, household income, residence, and floating population), maternal medication/supplement use during the 1st trimester of pregnancy (traditional Chinese medications and multivitamins), and paternal factors (alcohol consumption and smoking); We detected significant collinearities between gravidity and age, previous pregnancies with stillbirths and previous pregnancies with birth defects, a family history of CHDs and previous pregnancies with birth defects. Gravidity, previous pregnancies with stillbirths, and family history were excluded from the multivariable model. † Exposure window: in the 1st trimester of pregnancy (within 3 months after pregnancy). ‡ Exposure window: during the periconceptional period (3 months before pregnancy to the end of the 1st trimester).