Table 1.

Characteristics of subjects

	Mean (SD)	Range
Age (years)	21.1 (1.7)	197–25
Daily number of cigarettes smoked	17.3 (5.2)	10.5–30.0
Years of smoking	3.6 (2.1)	1–10
FTND score	2.2 (2.1)	0–7
Duration of menstrual cycle (days)	30.5 (2.5)	37–34
Duration of follicular phase (days)	8.2 (2.1)	6–9
Duration of luteal phase (days)	12.6 (1.4)	12–15

FTND: Fagerström Test for Nicotine Dependency.