Characteristics of 7699 pregnant women before and during the COVID-19 pandemic
| Items | N/mean (SD) | Pre-COVID-19 (N, %; mean, SD) | COVID-19 (N, %; mean, SD) | χ2/t | P value |
| Maternal age (years) | 30.07 (3.98) | 29.92 (3.91) | 30.29 (4.08) | −3.42 | 0.001 |
| Maternal age (years) | 8.262 | 0.016 | |||
| ≤24 | 487 | 297 (6.58) | 190 (5.96) | ||
| 25–35 | 6117 | 3614 (80.12) | 2503 (78.51) | ||
| ≥35 | 1095 | 600 (13.30) | 495 (15.53) | ||
| Ethnicity | |||||
| Han | 7227 | 4236 (93.90) | 2991 (93.82) | 0.022 | 0.881 |
| Other | 472 | 275 (6.10) | 197 (6.18) | ||
| Occupation | 0.202 | 0.653 | |||
| Unemployed | 911 | 528 (11.73) | 383 (12.07) | ||
| Employed | 6762 | 3972 (88.27) | 2790 (87.93) | ||
| Education | 7.782 | 0.051 | |||
| Primary school or less | 34 | 22 (0.49) | 12 (0.38) | ||
| Junior high school | 578 | 355 (7.88) | 223 (7.02) | ||
| Senior high school | 3774 | 2251 (49.94) | 1523 (47.92) | ||
| Undergraduate or above | 3299 | 1879 (41.69) | 1420 (44.68) | ||
| Gravidity | 1.99 (1.08) | 1.99 (1.07) | 2.00 (1.08) | −0.223 | 0.823 |
| Gravidity | 1.883 | 0.39 | |||
| 1 | 3068 | 1809 (40.10) | 1259 (39.49) | ||
| 2 | 2523 | 1451 (32.17) | 1072 (33.63) | ||
| ≥3 | 2108 | 1251 (27.73) | 857 (26.88) | ||
| Parity | 0.43 (0.53) | 0.43 (0.52) | 0.44 (0.54) | −0.815 | 0.415 |
| Parity | 1.362 | 0.506 | |||
| 1 | 3195 | 1849 (40.99) | 1346 (42.22) | ||
| 2 | 119 | 68 (1.51) | 51 (1.60) | ||
| ≥3 | 4385 | 2594 (57.50) | 1791 (56.18) | ||
| History of miscarriage | 0.09 (0.32) | 0.08 (0.32) | 0.09 (0.33) | −1.18 | 0.239 |
| History of miscarriage | 579 | 328 (7.27) | 251 (7.87) | 0.974 | 0.324 |
| History of induced abortion | 0.47 (0.76) | 0.48 (0.76) | 0.46 (0.76) | 0.88 | 0.379 |
| History of induced abortion | 2601 | 1559 (34.58) | 1042 (32.69) | 2.982 | 0.084 |
| Family history of chronic disease | 929 | 481 (10.74) | 448 (14.18) | 20.536 | <0.0001 |
| Prepregnancy BMI, kg/m2 | 22.04 (3.12) | 22.09 (3.17) | 21.97 (3.17) | 1.45 | 0.147 |
| Prepregnancy BMI, kg/m2 | 2.465 | 0.482 | |||
| Underweight (18.5) | 676 | 392 (8.69) | 284 (8.91) | ||
| Normal (18.5–24.9) | 5717 | 3375 (74.82) | 2342 (73.46) | ||
| Overweight (25–29.9) | 1079 | 610 (13.52) | 469 (14.71) | ||
| Obese (30) | 227 | 134 (2.97) | 93 (2.92) | ||
| The rate of gestational weight gain (kg /week) | 0.42 (0.09) | 0.42 (0.09) | 0.42 (0.09) | −1.035 | 0.301 |
| Gestational weight gain | 6.412 | 0.041 | |||
| Insufficient | 2115 | 1204 (26.69) | 911 (28.58) | ||
| Appropriate | 3144 | 1894 (41.99) | 1250 (39.21) | ||
| Excessive | 2440 | 1413 (31.32) | 1027 (32.21) | ||
| Prenatal visits | 11.95 (3.25) | 11.98 (3.27) | 11.90 (3.23) | 0.892 | 0.373 |
| Prenatal visits | 8.175 | 0.004 | |||
| <8 | 824 | 521 (11.55) | 303 (9.50) | ||
| ≥8 | 6875 | 3990 (88.45) | 2885 (90.50) | ||
| Total | 7699 | 4511 (58.59) | 3188 (41.41) |
Missing data: occupation, 26 (0.34%); education, 14 (0.18%); history of induced abortion, 2 (0.03%) and family history of chronic disease, 59 (0.77%).