Table 1 Baseline characteristics according to infant short sleep patterns in the Japan Environment and Children's Study (2011–2014).
Short sleep patterns | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 month of age | Total | – | – | – | – | SS | SS | SS | SS | |
6 months of age | – | – | SS | SS | – | – | SS | SS | ||
1 year of age | – | SS | – | SS | – | SS | – | SS | ||
n | (%) | (%) | (%) | (%) | (%) | (%) | (%) | (%) | (%) | |
No. of women | 63,418 | 44,359 | 1753 | 4373 | 721 | 10,061 | 525 | 1352 | 274 | |
Age at delivery (years) | ||||||||||
< 25 | 5010 | 7.9 | 7.5 | 8.0 | 8.6 | 11.4 | 8.4 | 13.7 | 10.7 | 13.9 |
25–29 | 17,251 | 27.2 | 27.4 | 22.8 | 28.3 | 20.5 | 27.6 | 22.5 | 26.2 | 24.1 |
30–34 | 23,150 | 36.5 | 37.0 | 36.9 | 34.2 | 32.6 | 36.0 | 33.0 | 34.3 | 33.6 |
≥ 35 | 18,007 | 28.4 | 28.1 | 32.3 | 29.0 | 35.5 | 28.0 | 30.9 | 28.9 | 28.5 |
Smoking habits | ||||||||||
Never smoked | 38,829 | 61.3 | 61.5 | 60.6 | 62.5 | 61.3 | 60.5 | 58.2 | 61.3 | 59.9 |
Ex-smokers who quit before pregnancy | 14,865 | 23.5 | 23.8 | 22.7 | 22.0 | 20.4 | 23.3 | 21.4 | 22.7 | 18.3 |
Smokers during early pregnancy | 9615 | 15.2 | 14.7 | 16.7 | 15.5 | 18.3 | 16.2 | 20.4 | 16.0 | 21.9 |
Alcohol consumption | ||||||||||
Never drank | 21,993 | 34.7 | 34.6 | 34.5 | 33.3 | 32.9 | 35.6 | 36.8 | 34.4 | 40.5 |
Ex-drinkers who quit before pregnancy | 11,390 | 18.0 | 18.2 | 18.8 | 17.3 | 19.1 | 17.4 | 17.3 | 16.6 | 17.5 |
Drinkers during early pregnancy | 29,980 | 47.3 | 47.2 | 46.8 | 49.4 | 48.0 | 47.0 | 45.9 | 49.0 | 42.0 |
Parity | ||||||||||
0 | 28,766 | 45.5 | 42.5 | 44.5 | 52.0 | 53.6 | 52.6 | 57.0 | 60.8 | 63.9 |
≥ 1 | 34,432 | 54.5 | 57.5 | 55.5 | 48.0 | 46.4 | 47.4 | 43.1 | 39.2 | 36.1 |
Gestational age at delivery (week) | ||||||||||
37 | 6041 | 9.5 | 9.2 | 9.8 | 8.2 | 9.3 | 11.4 | 11.2 | 10.4 | 12.4 |
38 | 14,532 | 22.9 | 22.7 | 20.8 | 21.2 | 20.8 | 25.2 | 24.2 | 23.0 | 25.2 |
39 | 18,776 | 29.6 | 29.8 | 29.1 | 30.6 | 29.0 | 28.6 | 27.8 | 29.1 | 26.6 |
40 | 17,830 | 28.1 | 28.4 | 30.2 | 28.5 | 28.7 | 26.5 | 27.2 | 27.1 | 23.0 |
41 | 6239 | 9.8 | 9.9 | 10.2 | 11.5 | 12.2 | 8.4 | 9.5 | 10.4 | 12.8 |
Educational background (years) | ||||||||||
< 13 | 20,697 | 32.9 | 32.4 | 35.8 | 32.8 | 38.7 | 32.9 | 41.3 | 35.4 | 43.9 |
≥ 13 | 42,263 | 67.1 | 67.6 | 64.2 | 67.2 | 61.3 | 67.1 | 58.7 | 64.7 | 56.1 |
Household income (million Japanese yen/year) | ||||||||||
< 6 | 42,713 | 71.9 | 71.4 | 71.8 | 72.7 | 75.1 | 73.3 | 79.0 | 72.1 | 77.1 |
≥ 6 | 16,673 | 28.1 | 28.6 | 28.2 | 27.3 | 24.9 | 26.7 | 21.1 | 27.9 | 22.9 |
Postpartum depressive symptoms 1 month after delivery were assessed by Edinburgh postnatal depression scale | ||||||||||
No (score < 8) | 54,317 | 86.7 | 87.7 | 85.7 | 83.3 | 80.9 | 85.3 | 79.5 | 82.5 | 75.0 |
Depressive (score ≥ 9) | 8366 | 13.4 | 12.3 | 14.3 | 16.7 | 19.1 | 14.7 | 20.5 | 17.5 | 25.0 |
Small for gestational age | ||||||||||
No | 58,632 | 92.8 | 92.8 | 92.7 | 93.3 | 92.5 | 92.7 | 90.1 | 91.6 | 90.5 |
Yes | 4566 | 7.2 | 7.2 | 7.3 | 6.7 | 7.5 | 7.3 | 9.9 | 8.4 | 9.5 |
Infant sex | ||||||||||
Boys | 32,306 | 50.9 | 50.9 | 53.2 | 53.2 | 55.8 | 49.5 | 46.9 | 51.9 | 54.7 |
Girls | 31,112 | 49.1 | 49.1 | 46.8 | 46.8 | 44.2 | 50.5 | 53.1 | 48.2 | 45.3 |
Feeding status at 1 month after birth | ||||||||||
Exclusive breastfeeding | 33,926 | 54.6 | 56.0 | 51.6 | 53.0 | 53.3 | 51.0 | 49.9 | 49.8 | 48.9 |
Partial breastfeeding or formula feeding | 28,170 | 45.4 | 44.0 | 48.4 | 47.1 | 46.7 | 49.0 | 50.1 | 50.2 | 51.1 |
