Table 3. Adjusted odds ratio of women ≥35 years compared to women <35 years.

Adjusted Odds Ratio of women ≥35 years (95% CI)
	1979	1990	2000	2010
Preterm
Primiparous	2.14 (2–2.28)	2.01 (1.91–2.12)	1.67 (1.60–1.74)	1.50 (1.46–1.55)
Multiparous	2.15 (2.07–2.22)	1.67 (1.62–1.73)	1.39 (1.35–1.43)	1.30 (1.26–1.33)
LBW
Primiparous	2.06 (1.95–2.18)	1.69 (1.62–1.77)	1.48 (1.44–1.53)	1.34 (1.31–1.37)
Multiparous	1.90 (1.83–1.97)	1.42 (1.38–1.46)	1.20 (1.17–1.23)	1.21 (1.18–1.24)

Dependent variable: Preterm birth/LBW.

Explanatory variables: infant sex, birthplace (urban area: 1, rural area: 0), and maternal age (≥35 years: 1, <35 years: 0).