Table 2.
Characteristics of study subjects (n = 97,464).
| n | % | ||
|---|---|---|---|
| Gestation (weeks) of In-T1 | Median(IQR) | 15.7 (12.3–22.1) | |
| No response | 530 | 0.5 | |
| Gestation (weeks) of In-T2 | Median(IQR) | 27.6 (25.3–31.7) | |
| No response | 526 | 0.5 | |
| Gestation (weeks) of M-T1 | Mean +/− SD | 16.8 +/− 7.4 | |
| Median(IQR) | 15.4 (12.4–19.4) | ||
| No response | 859 | 0.9 | |
| Gestation (weeks) of M-T2 | Mean +/− SD | 28.3 +/− 6.1 | |
| Median(IQR) | 27.7 (25.3–30.4) | ||
| No response | 913 | 0.9 | |
| Age | Mean +/− SD | 30.8 +/− 5.0 | |
| <30 years | 39,460 | 40.5 | |
| 30–34 years | 33,918 | 34.8 | |
| ≥35 years | 23,683 | 24.3 | |
| No response | 403 | 0.4 | |
| Marital status | Married | 92,478 | 94.9 |
| Single/divorced/widowed | 4183 | 4.3 | |
| No response | 803 | 0.8 | |
| Education | Junior high/high school | 35,109 | 36.0 |
| Technical/junior college | 40,517 | 41.6 | |
| University/graduate school | 20,816 | 21.4 | |
| No response | 1022 | 1.1 | |
| Family income | <4,000,000 yen | 36,280 | 37.2 |
| ≥4,000,000 and <6,000,000 yen | 29,788 | 30.6 | |
| ≥6,000,000 yen | 24,025 | 24.7 | |
| No response | 7371 | 7.6 | |
| Body mass index | <18.5 kg/m2 | 15,595 | 16.0 |
| ≥18.5 and <25 kg/m2 | 70,483 | 72.3 | |
| ≥25 kg/m2 | 10,301 | 10.6 | |
| No response | 1085 | 1.1 | |
| Smoking | Nonsmokers | 56,115 | 57.6 |
| Ever smokers | 35,632 | 36.6 | |
| Current smokers | 4615 | 4.7 | |
| No response | 1102 | 1.1 | |
| Alcohol consumption | Nondrinkers | 33,461 | 34.3 |
| Ever drinkers | 53,612 | 55.0 | |
| Current drinkers | 9570 | 9.8 | |
| No response | 821 | 0.8 | |
| Parity | Primipara | 38,397 | 39.4 |
| Multipara | 56,786 | 58.3 | |
| No response | 2281 | 2.3 | |
| Fertility treatment | Yes | 6463 | 6.6 |
| No | 90,595 | 93.0 | |
| No response | 406 | 0.4 | |
| History of spontaneous abortion | Yes | 18,410 | 18.9 |
| No | 77,476 | 79.5 | |
| No response | 1578 | 1.6 | |
| History of a mental health disorder | No | 89,531 | 91.9 |
| Yes | 7551 | 7.8 | |
| No response | 382 | 0.4 | |
| Hypertension | No | 95,766 | 98.3 |
| Yes | 1189 | 1.2 | |
| No response | 509 | 0.5 | |
| Diabetes | No | 95,909 | 98.4 |
| Yes | 1046 | 1.1 | |
| No response | 509 | 0.5 | |
| Mental health disorder | No | 96,183 | 98.7 |
| Yes | 772 | 0.8 | |
| No response | 509 | 0.5 | |
| Other pregnancy complication | No | 84,305 | 86.5 |
| Yes | 12,650 | 13.0 | |
| No response | 509 | 0.5 | |
| Hypertensive disorders of pregnancy | No | 93,896 | 96.3 |
| Mild | 2114 | 2.2 | |
| Severe | 945 | 1.0 | |
| No response | 509 | 0.5 | |
| Gestational diabetes | No | 94,302 | 96.8 |
| Yes | 2653 | 2.7 | |
| No response | 509 | 0.5 | |
| Other obstetric labor complication | No | 54,648 | 56.1 |
| Yes | 42,307 | 43.4 | |
| No response | 509 | 0.5 | |
In-T1: Interview within the maternal first trimester; In-T2: Interview within the second or third trimester; M-T1: Questionnaire within the maternal first trimester; M-T2: Questionnaire within the second or third trimester; IQR: Interquartile range; SD: Standard deviation.