Table 1.
Characteristics of the study participants
| Participants with available information about general anesthesia before 1 year of age (n = 69,653) |
Participants included in the longitudinal analysis of general anesthesia before 1 year of age (n = 33,543) |
|
|---|---|---|
| Maternal characteristics | ||
| Age at delivery, years | ||
| Mean (SD) | 31.3 (4.9) | 31.6 (4.8) |
| < 20 | 906 (1.3) | 258 (0.8) |
| 20–29 | 24,301 (34.9) | 11,119 (33.1) |
| 30–39 | 41,363 (59.4) | 20,577 (61.3) |
| ≥ 40 | 3,080 (4.4) | 1,589 (4.7) |
| Missing | 3 (0.0) | 0 (0.0) |
| Gestational age at birth, weeks, mean (SD) | 39.5 (1.1) | 39.5 (1.1) |
| Mode of delivery | ||
| Spontaneous | 40,789 (58.6) | 19,560 (58.3) |
| Induced | 12,612 (18.1) | 6,194 (18.5) |
| Vacuum or forceps | 4,150 (6.0) | 2,022 (6.0) |
| Cesarean section | 11,927 (17.1) | 5,680 (16.9) |
| Missing | 175 (0.3) | 87 (0.3) |
| Epidural analgesia | ||
| Yes | 1,461 (2.1) | 743 (2.2) |
| No | 68,192 (97.9) | 32,800 (97.3) |
| Use of any medication before pregnancy | ||
| Yes | 59,471 (85.4) | 28,993 (86.3) |
| No | 8,916 (12.8) | 4,047 (12.1) |
| Missing | 1,266 (1.8) | 563 (1.7) |
| Use of any medication during pregnancy | ||
| Yes | 47,775 (68.6) | 23,432 (69.9) |
| No | 20,650 (29.6) | 9,623 (28.7) |
| Missing | 1,228 (1.8) | 488 (1.5) |
| Body mass index before pregnancy | ||
| Mean (SD) | 21.2 (3.2) | 21.0 (3.1) |
| < 18.5 | 11,159 (16.0) | 5,469 (16.3) |
| 18.5–24.9 | 51,555 (74.0) | 25,034 (74.6) |
| ≥ 25.0 | 6,893 (9.9) | 3,022 (9.0) |
| Missing | 46 (0.1) | 18 (0.1) |
| Marital status during the first trimester | ||
| Married (including common-law marriage) | 66,380 (95.3) | 32,238 (96.1) |
| Divorced | 2,199 (3.2) | 963 (2.9) |
| Widowed | 8 (0.0) | 5 (0.0) |
| Other | 440 (0.6) | 159 (0.5) |
| Missing | 626 (0.9) | 178 (0.5) |
| Occupation during the first trimester | ||
| Yes | 45,357 (65.1) | 21,786 (64.9) |
| No | 22,273 (32.0) | 11,022 (32.9) |
| Missing | 2,023 (2.9) | 735 (2.2) |
| Smoking status | ||
| Never smoker | 41,784 (60.0) | 21,542 (64.2) |
| Ex-smoker (quit before pregnancy) | 16,198 (23.3) | 7,599 (22.7) |
| Ex-smoker (quit during early pregnancy) | 8,260 (11.9) | 3,302 (9.8) |
| Current smoker | 2,602 (3.7) | 856 (2.6) |
| Missing | 809 (1.2) | 249 (0.7) |
| Alcohol consumption | ||
| Never drinker | 23,761 (34.1) | 11,762 (35.1) |
| Ex-drinker | 38,174 (54.8) | 18,233 (54.4) |
| Current drinker | 7,063 (10.1) | 3,361 (10.0) |
| Missing | 655 (0.9) | 187 (0.6) |
| Education, years | ||
| ≤ 12 | 22,851 (32.8) | 9,867 (29.4) |
| 13–15 | 29,501 (42.4) | 14,356 (42.8) |
| ≥ 16 | 16,576 (23.8) | 9,133 (27.2) |
| Missing | 725 (1.0) | 187 (0.6) |
| Annual household income | ||
| < 4,000,000 JPY | 24,774 (35.6) | 11,261 (33.6) |
| < 8,000,000 JPY | 32,729 (47.0) | 16,547 (49.3) |
| ≥ 8,000,000 JPY | 7,430 (10.7) | 3,852 (11.5) |
| Missing | 4,720 (6.8) | 1,883 (5.6) |
| Child characteristics | ||
| Sex | ||
| Male | 35,433 (50.9) | 16,959 (50.6) |
| Female | 34,220 (49.1) | 16,584 (49.4) |
| Birth weight, grams | ||
| Mean (SD) | 3,064.5 (364.5) | 3,062.7 (362.7) |
| < 2500 | 3,608 (5.2) | 1,729 (5.2) |
| 2500–3999 | 65,396 (93.9) | 31,508 (93.9) |
| ≥ 4000 | 616 (0.9) | 290 (0.9) |
| Missing | 34 (0.0) | 16 (0.0) |
| Feeding method for the first 6 months of life | ||
| Breast | 30,523 (43.8) | 15,056 (44.9) |
| Bottle | 6,373 (9.1) | 2,553 (7.6) |
| Mixed | 32,757 (47.0) | 15,934 (47.5) |
| Older children living together | ||
| Yes | 37,707 (54.1) | 17,223 (51.3) |
| No | 31,551 (45.3) | 16,219 (48.4) |
| Missing | 395 (0.6) | 101 (0.3) |
| Nursery attendance at 12 months of age | ||
| Yes | 19,175 (27.5) | 8,160 (24.3) |
| No | 50,214 (72.1) | 25,309 (75.5) |
| Missing | 264 (0.4) | 74 (0.2) |
| General anesthesia before 1 year of age | ||
| None | 68,985 (99.0) | 33,360 (99.5) |
| Once | 570 (0.8) | 159 (0.5) |
| ≥ 2 times | 98 (0.1) | 24 (0.1) |
| General anesthesia between 1 and 2 years of age | ||
| None | 57,601 (82.7) | 33,543 (100.0) |
| Once | 809 (1.2) | – |
| ≥ 2 times | 102 (0.1) | – |
| Missing | 11,141 (16.0) | – |
| General anesthesia between 2 and 3 years of age | ||
| None | 53,119 (76.3) | 33,543 (100.0) |
| Once | 668 (1.0) | – |
| ≥ 2 times | 196 (0.3) | – |
| Missing | 15,670 (22.5) | – |
| General anesthesia between 3 and 4 years of age | ||
| None | 57,081 (82.0) | 33,543 (100.0) |
| Once | 854 (1.2) | – |
| ≥ 2 times | 119 (0.2) | – |
| Missing | 11,599 (16.7) | – |
Data are n (%) unless otherwise specified
SD standard deviation, JPY Japanese yen