Table 2.
Hazard ratios for Autism Spectrum Disorder (ASD) starting at 1 year of age according to defective placentation syndromes in general and sibling cohorts. Live-born singleton non-malformed children in Sweden 2000–2016.
| Defective placentation syndrome | General Cohort1 |
Sibling Cohort2 |
|
|---|---|---|---|
| Adjusted hazard ratio (95% CI)3, 4 | Adjusted hazard ratio (95% CI)5 | IPW-adjusted hazard ratio (95% CI)6 | |
|
| |||
| Placental abruption | |||
| No | 1.00 | 1.00 | 1.00 |
| Yes | 1.43 (1.18, 1.73) | 1.03 (0.62, 1.72) | 1.11 (0.68, 1.81) |
| Preeclampsia | |||
| No preeclampsia | 1.00 | 1.00 | 1.00 |
| Preeclampsia at ≥37 weeks without SGA7 | 1.07 (0.98, 1.18) | 0.86 (0.66, 1.13) | 0.86 (0.66, 1.13) |
| Preeclampsia at ≥37 weeks with SGA | 1.53 (1.27, 1.86) | 1.73 (1.00, 2.99) | 1.93 (1.13, 3.28) |
| Preeclampsia at 34 to 36 weeks | 1.50 (1.25, 1.79) | 1.55 (0.91, 2.65) | 1.45 (0.87, 2.43) |
| Preeclampsia at <34 weeks | 1.75 (1.41, 2.16) | 3.57 (1.73, 7.35) | 4.22 (2.09, 8.53) |
| Gestational age8 | |||
| Term | 1.00 | 1.00 | 1.00 |
| Moderately preterm spontaneous | 1.04 (0.96, 1.13) | 1.16 (0.94, 1.43) | 1.04 (0.85, 1.27) |
| Very/extremely preterm spontaneous | 2.59 (2.21, 3.03) | 2.53 (1.54, 4.17) | 2.36 (1.47, 3.79) |
| Moderately preterm medically indicated | 1.39 (1.24, 1.56) | 1.49 (1.08, 2.05) | 1.40 (1.01, 1.94) |
| Very/extremely preterm medically indicated | 1.88 (1.52, 2.33) | 2.50 (1.21, 5.15) | 1.41 (0.53, 3.74) |
The cohort comprises 1,645,455 children with 23,810 cases of ASD.
The cohort comprises 1,092,132 full siblings distributed in 490,737 families. There were 14,483 cases of ASD.
From proportional hazards models with age at first diagnosis of ASD as the outcome and each defective placentation syndrome as the exposure, adjusted for maternal age, country of origin, cohabitation with the child’s father, education level, parity, height, early-pregnancy body mass index, smoking during pregnancy, presence of a diagnosis of ASD in the mother or the father, maternal polycystic ovarian syndrome, and infant sex and year of birth. Estimates for type of preterm birth were further adjusted for preeclampsia and SGA. A robust estimate of the variance was specified in all models to account for siblings.
Complete case analysis; n = 1,467,692 with 20,520 cases of ASD.
From proportional hazards models with age at first diagnosis of ASD as the outcome, stratified by family. Models were adjusted for birth order, early-pregnancy body mass index, smoking during pregnancy, and infant sex. Estimates for type of preterm birth were further adjusted for preeclampsia and SGA. Complete case analyses; n = 940,475 with 11,880 cases of ASD.
Inverse probability weighting. Estimates are from weighted proportional hazards models. Stabilized weights were computed as the product of the inverse of exposure probability given the covariates in footnote 3 times the inverse of the probability of inclusion into the sibling cohort given covariates.
Birth weight-for-gestational age <10th percentile.
Term: ≥37 weeks. Moderately preterm: 32 to 36 weeks. Very/extremely preterm: 22 to 31 weeks.