Table 1.

Adjusted Odds Ratios of Asthma-related Outcomes across Preterm Birth Categories^*

	Preterm Birth (<37 wk); Ref = Term (37–41 wk)			Degree of Prematurity; Ref = Full Term (39–41 wk)
				Early Preterm (22–31 wk)			Late Preterm (32–36 wk)			Early Term (37–38 wk)
	AOR	95% CI	P Value	AOR	95% CI	P Value	AOR	95% CI	P Value	AOR	95% CI	P Value
Outcome at ages 0–5 yr (N = 2,540)
Diagnosis
Ever asthma (≥1)	2.45	(1.98–3.04)	<0.001	5.90	(4.19–8.31)	<0.001	1.70	(1.30–2.23)	<0.001	1.05	(0.80–1.38)	0.718
Recurrent asthma (≥2)	2.28	(1.81–2.88)	<0.001	4.13	(2.88–5.93)	<0.001	1.70	(1.27–2.28)	<0.001	0.95	(0.70–1.29)	0.763
Recurrent asthma (≥4)	2.00	(1.52–2.61)	<0.001	4.09	(2.72–6.13)	<0.001	1.54	(1.09–2.19)	0.015	1.17	(0.83–1.66)	0.364
Ever wheezing (≥1)	1.85	(1.48–2.31)	<0.001	3.15	(2.21–4.49)	<0.001	1.67	(1.26–2.20)	<0.001	1.27	(0.97–1.66)	0.084
Recurrent wheezing (≥2)	2.29	(1.71–3.09)	<0.001	4.16	(2.66–6.51)	<0.001	1.92	(1.31–2.82)	<0.001	1.21	(0.82–1.79)	0.339
Recurrent wheezing (≥4)	2.85	(1.83–4.43)	<0.001	6.17	(3.30–11.55)	<0.001	2.12	(1.17–3.82)	0.013	1.20	(0.64–2.26)	0.567
Ever asthma exacerbation	2.48	(1.94–3.17)	<0.001	4.49	(3.08–6.55)	<0.001	2.05	(1.50–2.79)	<0.001	1.14	(0.82–1.57)	0.435
Medication
Any asthma medication	2.22	(1.83–2.68)	<0.001	5.74	(4.14–7.96)	<0.001	1.68	(1.33–2.12)	<0.001	1.22	(0.97–1.52)	0.088
Long-term controller	2.42	(1.89–3.09)	<0.001	5.82	(4.03–8.39)	<0.001	1.54	(1.12–2.12)	0.008	1.00	(0.72–1.39)	0.988
SABAs/long-term controller	2.26	(1.87–2.74)	<0.001	5.60	(4.03–7.76)	<0.001	1.73	(1.36–2.19)	<0.001	1.21	(0.96–1.52)	0.109
Any oral steroid use	2.45	(1.95–3.08)	<0.001	5.35	(3.76–7.60)	<0.001	1.87	(1.39–2.51)	<0.001	1.18	(0.87–1.59)	0.292
Outcome at ages 6–9 yr (N = 1,072)†
Diagnosis
Ever asthma (≥1)	2.28	(1.66–3.12)	<0.001	4.92	(2.91–8.31)	<0.001	2.04	(1.38–3.01)	<0.001	1.46	(0.98–2.16)	0.062
Recurrent asthma (≥2)	2.94	(2.08–4.15)	<0.001	5.68	(3.27–9.86)	<0.001	2.46	(1.60–3.80)	<0.001	1.22	(0.76–1.95)	0.409
Recurrent asthma (≥4)	2.40	(1.57–3.67)	<0.001	3.92	(2.05–7.47)	<0.001	1.97	(1.16–3.36)	0.013	1.10	(0.61–1.98)	0.744
Ever asthma exacerbation	2.05	(1.35–3.12)	<0.001	3.91	(2.04–7.50)	<0.001	2.09	(1.21–3.60)	0.008	1.83	(1.07–3.15)	0.029
Medication
Any asthma medication	2.05	(1.51–2.77)	<0.001	3.82	(2.28–6.41)	<0.001	1.87	(1.29–2.71)	<0.001	1.31	(0.90–1.90)	0.163
Long-term controller	2.64	(1.84–3.77)	<0.001	3.57	(2.03–6.28)	<0.001	2.26	(1.47–3.49)	<0.001	0.99	(0.61–1.61)	0.972
SABAs/long-term controller	2.17	(1.59–2.96)	<0.001	4.00	(2.37–6.73)	<0.001	2.02	(1.38–2.96)	<0.001	1.35	(0.91–1.99)	0.133
Any oral steroid use	2.16	(1.39–3.36)	<0.001	3.21	(1.68–6.15)	<0.001	1.60	(0.93–2.75)	0.092	0.90	(0.50–1.65)	0.743

Definition of abbreviations: AOR = adjusted odds ratio; CI = confidence interval; Ref = reference; SABAs = short-acting β-agonists.

See Table E1 for description of asthma measures.

^*Adjusted for maternal age, race/ethnicity, marital status, education, history of asthma, maternal persistent smoking during the index pregnancy; child sex and age, followed years, and family member smoking.

^†Wheezing measures were excluded because of low prevalence during ages 6–9 years.