Table 4.

Associations of maternal age at delivery with allergic rhinitis in offspring, stratified by sex, birth order, and environmental tobacco smoke (ETS) exposure during pregnancy.

Maternal age at delivery, years	n (%)a	AOR	(95% CI)b	P	n (%)a	AOR	(95% CI)b	P
	Female (n = 581)				Male (n = 763)
<25	13 (56.5)	0.93	(0.31–2.83)	0.903	13 (52.0)	0.44	(0.17–1.14)	0.091
25–29	75 (54.7)	0.77	(0.48–1.22)	0.268	129 (64.5)	0.99	(0.66–1.48)	0.950
30–34	162 (55.5)	Reference		–	230 (63.5)	Reference		–
35–39	57 (53.3)	1.15	(0.70–1.89)	0.582	81 (52.3)	0.71	(0.46–1.09)	0.117
≥40	18 (81.8)	7.02	(1.89–26.14)	0.004	15 (71.4)	2.90	(0.85–9.86)	0.089
	First-born child (n = 752)				Second or later child (n = 592)
<25	24 (57.1)	0.54	(0.29–1.47)	0.132	2 (33.3)	0.31	(0.04–2.20)	0.241
25–29	158 (66.4)	0.98	(0.71–1.53)	0.928	46 (46.5)	0.75	(0.45–1.26)	0.284
30–34	236 (64.8)	Reference		–	156 (53.8)	Reference		–
35–39	56 (59.6)	0.91	(0.62–1.72)	0.723	82 (48.8)	0.82	(0.54–1.26)	0.369
≥40	13 (92.9)	8.62	(1.07–69.46)	0.043	20 (69.0)	4.12	(1.44–11.79)	0.008
	ETS exposure during pregnancy (n = 547)				No ETS exposure during pregnancy (n = 765)
<25	15 (51.7)	0.51	(0.20–1.32)	0.164	9 (56.3)	0.50	(0.15–1.62)	0.247
25–29	102 (62.2)	1.06	(0.66–1.70)	0.810	96 (59.3)	0.84	(0.55–1.26)	0.393
30–34	139 (57.9)	Reference		–	247 (60.8)	Reference		–
35–39	46 (47.9)	0.76	(0.44–1.32)	0.324	85 (54.1)	0.88	(0.58–1.32)	0.529
≥40	12 (66.7)	4.32	(1.18–15.75)	0.027	20 (83.3)	6.57	(1.77–24.33)	0.005

AOR: adjusted odds ratio, CI: confidence interval. ETS: environmental tobacco smoke.

^an (%) refers to the numbers (%) of subjects with physician-diagnosed allergic rhinitis.

^bCovariates included in the adjusted models are child's age, sex, prematurity, birth order, cesarean delivery, pregnancy-related complications, parental allergic diseases, parental ethnicity, parental smoking status, parental education, and household income. P < 0.05 is bold.