Table 1.
Characteristics of study subjects
| Characteristic | Non-antibiotics group (422,740) | Antibiotics group (484,202) | Total | p |
|---|---|---|---|---|
| n (%) | n (%) | |||
| Maternal age (years) | < 0.001 | |||
| < 25 | 72,366 (17.1) | 90,395 (18.7) | 162,761 | |
| 25–29 | 159,287 (37.7) | 180,320 (37.2) | 339,607 | |
| 30–34 | 140,761 (33.3) | 151,804 (31.4) | 292,565 | |
| ≥ 35 | 50,326 (11.9) | 61,683 (12.7) | 112,009 | |
| Mode of delivery | < 0.001 | |||
| Vaginal delivery | 313,169 (74.1) | 291,785 (60.3) | 604,954 | |
| Cesarean section | 109,571 (25.9) | 192,417 (39.7) | 301,988 | |
| Maternal comorbidity | ||||
| Diabetes mellitus | 1822 (0.4) | 3284 (0.7) | 5,106 | < 0.001 |
| Hypertension | 1752 (0.4) | 3452 (0.7) | 5,204 | < 0.001 |
| Hyperlipidemia | 3365 (0.8) | 6074 (1.3) | 9,439 | < 0.001 |
| Maternal allergic disease | ||||
| Asthma | 8954 (2.1) | 15,594 (3.2) | 24,548 | < 0.001 |
| Allergic rhinitis | 65,455 (15.5) | 95,671 (19.8) | 161,126 | < 0.001 |
| Atopic dermatitis | 7223 (1.7) | 11,070 (2.3) | 18,293 | < 0.001 |
| Pregnancy-related complication | ||||
| Anemia | 15,979 (3.8) | 24,690 (5.1) | 40,669 | < 0.001 |
| Gestational diabetes mellitus | 6217 (1.5) | 7401 (1.5) | 13,618 | 0.024 |
| Gestational hypertension | 1485 (0.4) | 2389 (0.5) | 3,874 | < 0.001 |
| Pre-eclampsia or eclampsia | 2986 (0.7) | 5390 (1.1) | 8,376 | < 0.001 |
| Placenta previa or abruptio placentae | 9664 (2.3) | 15,581 (3.2) | 25,245 | < 0.001 |
| Neonatal gender | < 0.001 | |||
| Female | 205,227 (48.5) | 231,737 (47.9) | 436,964 | |
| Male | 217,513 (51.5) | 252,465 (52.1) | 469,978 | |
| Timing of antibiotics exposure | ||||
| 1st trimester | 288,434 (59.6) | 288,434 | ||
| 2nd trimester | 30,173 (6.2) | 30,173 | ||
| 3rd trimester | 165,595 (34.2) | 165,595 | ||
| Cumulative number of antibiotics | ||||
| 1 time | 279,783 (57.8) | 279,783 | ||
| 2 times | 108,969 (22.5) | 108,969 | ||
| ≥ 3 times | 95,450 (19.7) | 95,450 |