. Author manuscript; available in PMC: 2015 Nov 1.

Published in final edited form as: Paediatr Perinat Epidemiol. 2014 Oct 30;28(6):489–497. doi: 10.1111/ppe.12154

Table 2.

Relative risk^a of preterm, term, and postterm birth for mothers with asthma, atopic dermatitis, allergic rhinoconjunctivitis, and no atopic disease in a cohort of 1,974,226 births

	Gestational age at birth

	23–31 weeks (n=19,873)		32–36 weeks (n=96,947)		37–41 weeks (n=1,586,501)		42–44 weeks (n=270,905)

	Crude RR^b [95% CI]	Adjusted RR^c [95% CI]	Crude RR^b [95% CI]	Adjusted RR^c [95% CI]	Crude RR^b [95% CI]	Adjusted RR^c [95% CI]	Crude RR^b [95% CI]	Adjusted RR^c [95% CI]

Mothers with
asthma	1.25 [1.12, 1.38]	1.33 [1.18, 1.50]	1.18 [1.13, 1.24]	1.13 [1.07, 1.18]	0.98 [0.97, 0.98]	0.98 [0.97, 0.99]	1.06 [1.03, 1.09]	1.05 [1.02, 1.08]
atopic dermatitis	0.78 [0.71, 0.86]	0.78 [0.70, 0.87]	0.94 [0.90, 0.97]	0.92 [0.88, 0.95]	1.01 [1.00, 1.01]	1.01 [1.01, 1.01]	1.00 [0.98, 1.02]	0.98 [0.96, 1.00]
allergic rhinoconjunctivitis	0.64 [0.48, 0.86]	0.75 [0.55, 1.03]	0.87 [0.78, 0.97]	0.86 [0.77, 0.96]	1.01 [1.00, 1.02]	1.01 [1.00, 1.02]	1.00 [0.94, 1.05]	1.01 [0.96, 1.07]
no atopic disease		Reference		Reference		Reference		Reference

Relative risks were obtained by comparing risks within each gestational age category.

Separate analyses were performed for each maternal atopic disease. The reference groups consisted of mothers without each atopic disease (not shown).

Adjusted for year of birth, other maternal diseases in the table, maternal age, single mother at birth, maternal and paternal education, parity, and seasonality.

CI, confidence interval; RR, relative risk