Table 2.

Hazard ratios of attention-deficit/hyperactivity disorder according to maternal and paternal asthma

Parental asthma	Offspring ADHD (n)	N	Person- years at risk	Crude HR	Adjusted HR (95% CI)
All children
Non-asthmatic mothers	24,619	877,936	10,456,945	1 (ref)	1 (ref)
Asthmatic mothers	3,161	83,266	880,402	1.67 (1.61 – 1.73)	1.41 (1.36 – 1.46)
Non-asthmatic fathers	25,879	894,038	10,625,998	(ref)	1 (ref)
Asthmatic fathers	1,901	67,164	711,349	1.19 (1.14 – 1.25)	1.13 (1.08 – 1.18)
Boys
Non-asthmatic mothers	17,607	450,564	5,334,356	1 (ref)	1 (ref)
Asthmatic mothers	2,242	42,706	448,652	1.63 (1.56 – 1.70)	1.39 (1.33 – 1.45)
Non-asthmatic fathers	18,465	458,980	5,422,165	1 (ref)	1 (ref)
Asthmatic fathers	1,384	34,290	360,843	1.20 (1.14 – 1.27)	1.14 (1.08 – 1.21)
Girls
Non-asthmatic mothers	7,012	427,372	5,122,589	1 (ref)	1 (ref)
Asthmatic mother	919	40,560	431,750	1.79 (1.67 – 1.91)	1.46 (1.36 – 1.57)
Non-asthmatic fathers	7,414	435,058	5,203,833	1 (ref)	1 (ref)
Asthmatic fathers	517	32,874	350,506	1.18 (1.08 – 1.29)	1.09 (0.99 – 1.19)

Abbrevations: HR, hazard ratio; CI, confidence interval.

Adjusted for maternal age at delivery, parity, maternal smoking during pregnancy, maternal mental disorders before pregnancy, maternal cohabiting status, place of residence at delivery, low social class at delivery, large family size, sex of the child, and calendar year of birth. Maternal asthma and paternal asthma were mutually adjusted in the models.