Table 1.
Maternal characteristics 6691282165####
| Characteristics | Current study (n = 4,683) |
All pregnancies (n = 103,060) |
|
|---|---|---|---|
| n (%) | n (%) | p-value* | |
| Age at delivery (years), mean ± SD | 31.9 ± 4.8 | 31.2 ± 5.1 | < 0.01 |
| <25 | 295 (6.3) | 10,125 (9.8) | |
| 25–<30 | 1,206 (25.8) | 27,760 (26.9) | |
| 30–<35 | 1,732 (37.0) | 35,650 (34.6) | |
| ≥35 | 1,450 (31.0) | 27,414 (26.6) | |
| Missing | 0 (0.0) | 2,111 (2.0) | |
| Education (years) | < 0.01 | ||
| <10 | 144 (3.1) | 4,726 (4.6) | |
| 10–<13 | 2,558 (54.6) | 54,579 (53) | |
| 13–<17 | 1,867 (39.9) | 36,740 (35.6) | |
| ≥17 | 74 (1.6) | 1,434 (1.4) | |
| Missing | 40 (0.9) | 5,581 (5.4) | |
| Parity | < 0.01 | ||
| 0 | 2,080 (44.4) | 40,395 (39.2) | |
| ≥1 | 2,603 (55.6) | 59,642 (57.9) | |
| Missing | 0 (0.0) | 3,023 (2.9) | |
| Prepregnancy BMI (kg/m2), mean ± SD | 20.5 ± 2.9 | 21.2 ± 3.3 | < 0.01 |
| <25 | 1,082 (23.1) | 16,629 (16.1) | |
| 25–<30 | 3,271 (69.8) | 74,816 (72.6) | |
| ≥30 | 329 (7.0) | 10,939 (10.6) | |
| Missing | 1 (0.0) | 676 (0.7) | |
|
Annual household income (million Japanese yen) |
< 0.01 | ||
| <2 | 210 (4.5) | 5,167 (5.0) | |
| 2–<4 | 1,425 (30.4) | 31,460 (30.5) | |
| 4–<6 | 1,453 (31.0) | 30,082 (29.2) | |
| 6–<8 | 750 (16.0) | 14,486 (14.1) | |
| 8–<10 | 302 (6.4) | 5,954 (5.8) | |
| ≥10 | 207 (4.4) | 3,888 (3.8) | |
| Missing | 336 (7.2) | 12,023 (11.7) | |
| Smoking status | < 0.01 | ||
| Never smoked | 2,897 (61.9) | 56,156 (54.5) | |
| Quit before pregnancy | 1,008 (21.5) | 23,280 (22.6) | |
| Smoked in early pregnancy | 732 (15.6) | 17,791 (17.3) | |
| Missing | 46 (1.0) | 5,833 (5.7) | |
| Alcohol consumption | 0.26 | ||
| Never consumed | 1,607 (34.3) | 32,615 (31.6) | |
| Stopped consuming before pregnancy | 770 (16.4) | 16,740 (16.2) | |
| Consumed in early pregnancy | 2,264 (48.3) | 47,865 (46.4) | |
| Missing | 42 (0.9) | 5,840 (5.7) | |
| Hypertensive disorders of pregnancy | 348 (7.4) | 3,145 (3.1) | < 0.01 |
| Missing | 0 (0.0) | 2,375 (2.3) | |
| Gestational diabetes mellitus | 48 (1.0) | 2,713 (2.6) | < 0.01 |
| Missing | 0 (0.0) | 2,375 (2.3) | |
| Diabetes mellitus | 133 (2.8) | 1,101 (1.1) | < 0.01 |
| Missing | 0 (0.0) | 2,375 (2.3) |
Note: BMI: Body mass index; SD: Standard deviation
* Chi-square test was performed for each characteristic