Table 3.
Associations of perinatal factors with subsequent risk of stress-related disorders.
| Population analysisa | Sibling analysisb | |||||
|---|---|---|---|---|---|---|
| Individuals, N | Cases, N (IR) | HR (95% CI) | Individuals, N | Cases, N (IR) | HR (95% CI) | |
| Mode of delivery | ||||||
| Unassisted vaginal delivery | 2,807,264 | 46,403 (0.9) | 1.00 | 2,129,565 | 31,700 (0.8) | 1.00 |
| Assisted vaginal delivery | 223,453 | 3001 (0.8) | 0.97 (0.94–1.01) | 150,139 | 1880 (0.7) | 1.03 (0.95–1.11) |
| Cesarean section | 405,030 | 6107 (1.0) | 1.09 (1.06–1.12) | 274,531 | 3853 (0.9) | 1.10 (1.02–1.20) |
| Gestational age, weeks | ||||||
| <32 | 18,550 | 385 (1.3) | 1.35 (1.22–1.49) | 11,314 | 216 (1.2) | 1.16 (0.93–1.45) |
| 32–36 | 150,297 | 2816 (1.1) | 1.15 (1.10–1.19) | 103,199 | 1771 (1.0) | 0.99 (0.91–1.07) |
| 37–41 | 2,937,327 | 46,088 (0.9) | 1.00 | 2,204,446 | 29,557 (0.8) | 1.00 |
| ⩾42 | 329,573 | 6222 (0.9) | 1.02 (1.00–1.05) | 235,276 | 4034 (0.9) | 1.00 (0.95–1.06) |
| Birth weight for gestational age, percentile | ||||||
| <3rd | 104,580 | 2565 (1.2) | 1.23 (1.18–1.28) | 67,113 | 1469 (1.1) | 1.00 (0.91–1.10) |
| 3rd to <10th | 242,603 | 4948 (1.1) | 1.10 (1.07–1.14) | 165,389 | 3033 (0.9) | 1.00 (0.94–1.06) |
| 10th to 90th | 2,765,814 | 43,273 (0.9) | 1.00 | 2,068,852 | 29,557 (0.8) | 1.00 |
| >90th to 97th | 197,625 | 2743 (0.8) | 0.97 (0.93–1.00) | 155,635 | 1985 (0.8) | 0.98 (0.91–1.05) |
| >97th | 112,165 | 1730 (0.9) | 1.06 (1.01–1.11) | 87,691 | 1224 (0.9) | 1.06 (0.97–1.17) |
| Apgar score at 5 minc | ||||||
| Low | 31,572 | 608 (1.1) | 1.22 (1.12–1.32) | 21,139 | 363 (1.0) | 1.13 (0.95–1.33) |
| Normal | 3,182,721 | 49,080 (0.9) | 1.00 | 2,392,981 | 33,762 (0.8) | 1.00 |
Note: Individuals with missing information on birth weight for gestational age (N = 12,960, 0.38%) and missing information on 5 min Apgar score (N = 221,454, 6.45%) were not included in the corresponding analysis.
HRs and 95% CIs were estimated from multivariable Cox regression models.
N number, IR incidence rate (per 1000 person-years in crude), HR hazard ratio, CI confidence interval.
aHRs were stratified on calendar year of birth (1973–1977, 1978–1981, 1982–1986, 1987–1991, 1992–1996, 1997–2001, or 2002–2008), and adjusted for offspring sex (female or male), attained age, maternal country of birth (Nordic, non-Nordic, or unknown), maternal educational level (<10 years,10–11, 12, 13–14, 15+, or unknown), and history of parental psychiatric disorders.
bHRs were stratified on full-siblingship and adjusted for offspring sex (female or male), attained age, and calendar year of birth.
cLow Apgar score was defined as Apgar score < 7.