Confounding with familial determinants affects the association between mode of delivery and childhood asthma medication – a national cohort study

Table 4 Conditional logistic regression models for the association between mode of delivery and dispense of at least one prescription of inhaled cortisone at least once in discordant sibling-pairs

Mode of delivery	Unadjusted		Model 1		Model 2		Model 3
	OR	95% CI	aOR	95% CI	aOR	95% CI	aOR	95% CI
2-5 years (n= 7 688 contrasting sib pairs)
Vaginal¹	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
Elective CS	1.21	1.05, 1,41	1.19	1.03, 1.39	1.22	1.05, 1.42	1.23	1.05, 1.43
Emergency CS	0.88	0.74, 1.06	0.84	0.70, 1.02	0.95	0.79, 1.15	0.95	0.78, 1.14
Vacuum extraction	0.94	0.83, 1.06	0.89	0.79, 1.01	1.06	0.92, 1.21	1.05	0.92, 1.20
6-9 years (n=2 290 contrasting sib pairs)
Vaginal¹	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
Elective CS	1.05	0.79, 1.40	1.08	0.80, 1.46	1.09	0.81, 1.47	1.06	0.78, 1.44
Emergency CS	1.05	0.75, 1.46	1.00	0.71, 1.42	1.03	0.73, 1.46	1.02	0.72, 1.44
Vacuum extraction	0.93	0.74, 1.17	0.89	0.70, 1.12	0.91	0.71, 1.17	0.92	0.72, 1.18

Odds ratios in relation to the reference, Non-instrumental vaginal delivery in different age groups.
Abbreviations: CI, confidence interval; aOR, adjusted odds ratio; OR, odds ratio.
Model 1 – adjusted for infant gender, Model 2 – also adjusted for maternal age and parity, Model 3 – also adjusted for small for gestational age, large for gestational age, preeclampsia, maternal body mass index, maternal diabetes and gestational diabetes and neonatal respiratory distress.
¹Non-instrumental vaginal delivery.

ISSN: 1710-1492