Table 2 Analyses of inter-pregnancy intervals, Cox proportional hazards regression of time from one birth to next
From: Reproductive stoppage in autism spectrum disorder in a population of 2.5 million individuals
Hazard ratio (95% confidence interval) | ||||||
|---|---|---|---|---|---|---|
All birth orders combined | Birth order specific | |||||
First to second | Second to third | |||||
ASD in any previously born | ASD in immediately previously born | ASD in first-born | ASD in first-born | ASD in second-born | ASD in both first- and second-born | |
Crude | ||||||
0.79 (0.78–0.80) | 1.05 (1.03–1.07) | 0.87 (0.86–0.89) | 1.08 (1.05–1.11) | 1.17 (1.13–1.22) | 1.05 (0.93–1.17) | |
Adjusted | ||||||
Birth ordera | 0.97 (0.96–0.99) | 0.94 (0.92–0.96) | NA | NA | NA | NA |
Maternal age | 0.82 (0.81–0.83) | 1.01 (1.00–1.03) | 0.88 (0.87–0.90) | 1.09 (1.05–1.12) | 1.11 (1.08–1.15) | 1.06 (0.95–1.19) |
Birth period | 0.80 (0.79–0.81) | 1.04 (1.02–1.05) | 0.88 (0.86–0.89) | 1.09 (1.05–1.12) | 1.17 (1.13–1.21) | 1.06 (0.95–1.19) |
Sex | 0.78 (0.77–0.79) | 1.05 (1.03–1.06) | 0.87 (0.85–0.89) | 1.08 (1.05–1.11) | 1.17 (1.13–1.21) | 1.04 (0.93–1.17) |
Paternal age | 0.81 (0.8–0.82) | 1.03 (1.01–1.04) | 0.88 (0.86–0.89) | 1.09 (1.06–1.12) | 1.14 (1.10–1.18) | 1.08 (0.96–1.20) |
Maternal education | 0.79 (0.78–0.81) | 1.06 (1.05–1.08) | 0.88 (0.86–0.90) | 1.10 (1.06–1.13) | 1.18 (1.14–1.22) | 1.05 (0.94–1.17) |
All of abovea | 1.00 (0.99–1.02) | 0.97 (0.95–0.98) | 0.90 (0.88–0.91) | 1.12 (1.08–1.15) | 1.16 (1.12–1.20) | 1.11 (0.99–1.24) |