Table 1. Baseline Characteristics Among Different Hepatitis B Virus (HBV) Infection Status Groups.
| Characteristic | No. (%) | P valuea | ||
|---|---|---|---|---|
| Uninfected women (n = 2 951 482) | Women with previous infection (n = 393 332) | Women with new infection (n = 345 613) | ||
| Time interval between examination and LMP, median (IQR), mo | 2.24 (0.79-4.89) | 2.38 (0.89-4.99) | 2.21 (0.83-4.79) | NA |
| Paternal age at LMP, y | ||||
| Mean (SD) | 28.60 (4.72) | 29.20 (4.83) | 28.90 (4.82) | <.001b |
| Median (IQR) | 28 (25-31) | 28 (26-32) | 28 (25-31) | |
| Maternal nationality | ||||
| Han | 2 731 028 (92.5) | 360 986 (91.8) | 313 431 (90.7) | <.001 |
| Other | 134 008 (4.6) | 24 690 (6.3) | 24 499 (7.1) | |
| Missing data | 86 446 (2.9) | 7656 (1.9) | 7683 (2.2) | |
| Maternal smoking | ||||
| No | 2 924 510 (99.1) | 388 431 (98.8) | 342 936 (99.2) | <.001 |
| Yes | 8538 (0.3) | 1367 (0.3) | 792 (0.2) | |
| Missing data | 18 434 (0.6) | 3534 (0.9) | 1885 (0.6) | |
| Maternal early pregnancy common cold | ||||
| No | 2 937 873 (99.5) | 391 225 (99.5) | 344 197 (99.6) | <.001 |
| Yes | 13 609 (0.5) | 2107 (0.5) | 1416 (0.4) | |
| Maternal early pregnancy medication | ||||
| No | 2 922 933 (99.0) | 388 408 (98.8) | 342 298 (99.0) | <.001 |
| Yes | 28 549 (1.0) | 4924 (1.2) | 3315 (1.0) | |
| Paternal serum HBsAg status | ||||
| Negative | 2 745 540 (93.0) | 334 768 (85.1) | 295 572 (85.5) | <.001 |
| Positive | 155 620 (5.3) | 48 420 (12.3) | 42 654 (12.4) | |
| Missing data | 50 322 (1.7) | 10 144 (2.6) | 7387 (2.1) | |
| Paternal HBV infection status | ||||
| Uninfected | 2 611 648 (88.5) | 253 012 (64.3) | 260 010 (75.2) | <.001 |
| Previous infection | 95 778 (3.3) | 76 573 (19.5) | 28 576 (8.3) | |
| New infection | 153 975 (5.2) | 47 944 (12.2) | 42 242 (12.2) | |
| Missing data | 90 081 (3.0) | 15 803 (4.0) | 14 785 (4.3) | |
| Maternal family history of CHD | ||||
| No | 2 949 871 (99.9) | 392 998 (99.9) | 345 428 (99.9) | <.001 |
| Yes | 1611 (0.1) | 334 (0.1) | 185 (0.1) | |
| Paternal family history of CHD | ||||
| No | 2 950 245 (99.9) | 393 091 (99.9) | 345 446 (99.9) | <.001 |
| Yes | 1237 (0.04) | 241 (0.1) | 167 (0.1) | |
| Maternal early pregnancy folacin use | ||||
| No | 400 877 (13.6) | 66 942 (17.0) | 62 408 (18.1) | <.001 |
| Yes | 2 491 885 (84.4) | 320 613 (81.5) | 277 583 (80.3) | |
| Missing data | 58 720 (2.0) | 5777 (1.5) | 5622 (1.6) | |
| Newborn with CHDs | ||||
| No | 2 950 682 (99.9) | 393 191 (99.9) | 345 523 (99.9) | .007 |
| Yes | 800 (0.03) | 141 (0.04) | 90 (0.03) | |
Abbreviations: CHDs, congenital heart diseases; HBsAg, hepatitis B surface antigen; LMP, last menstrual period; NA, not available.
a
The χ2 test was used unless otherwise indicated.
b
The Kruskal-Wallis test was used.