Figure 1.

Multivariable-adjusted cumulative probability of remaining premenopausal until 45 years of age across women who never worked rotating night shifts (solid blue line), and those who worked 20 or more months of rotating night shifts (hashed red line), during the prior 2 years. Adjusted for age, smoking status (never, past or current smoker), age at first birth and parity combined (nulliparous; age at first birth <24, 1–2 children; age at first birth 24–29, 1–2 children; age at first birth >29, 1–2 children; age at first birth <23, >2 children; age at first birth 24–29, >3 children; age at first birth >29, >2 children), body mass index (<18.5, 18.5–20, >20–22.5, >22.5–25, >25–30 and >30 kg/m²), duration of oral contraceptive use (0, 1–23, 24–47, 48–71, 72–95, 96–119 and >120 months), duration breast fed (never, ≤1 y, >1 y), alcohol consumption (0, >0–1, >1–4, >4–8, >8–12, >12 g/wk), physical activity (≤3, >3–9,> 9–19, >19–27, >27–42, >42 metabolic equivalent tasks/wk), age at menarche (≤9, 10, 11, 12, 13, 14, 15, ≥16 y) and sleep in 24 h (≤4, 5, 6, 7, 8, ≥9 h).