Table 2.

Association between parity, age at first birth, and relative risk of death from asthma over a 32-year follow-up period.

Parameters	Variables	Crude RR (95% CI)	Multivariate-adjusted RR * (95% CI)
Age at recruitment (1st birth)	≤25	1.00	1.00
	26–30	1.25 (0.93–1.66)	1.14 (1.05–1.91)
	>30	3.50 (2.36–5.20)	3.15 (2.06–4.82)
		p < 0.0001 for linear trend	p < 0.0001 for linear trend
Parity	1	1.00	1.00
	2	0.58 (0.42–0.82)	0.75 (0.53–1.08)
	≥3	0.45 (0.32–0.34)	0.53 (0.36–0.78)
		p < 0.0001 for linear trend	p = 0.0009 for linear trend
Marital status	Married	1.00	1.00
	Not married	2.66 (1.58–4.48)	1.94 (1.14–3.31)
Years of schooling	≤9	1.00	1.00
	>9	0.56 (0.42–0.74)	0.48 (0.36–0.65)
Birth place	Hospital/clinic	1.00	1.00
	Home	2.12 (1.33–3.40)	2.05 (1.27–3.31)