Cigarette smoking and effects on menstrual function

Objective: To examine the relationship between smoking and menstrual functi on, using biologic measures rather than self-report of menstrual cycle char acteristics. Methods: In a prospective study, 408 women collected urine daily for one to seven menstrual segments (cycles), maintained daily diaries, and completed detailed interviews. Smoking data from the diaries were averaged over each segment and verified by cotinine assay. Urine samples were analyzed for me tabolites of steroid hormones to define the day of ovulation and various me nstrual characteristics, including: 1) segment, follicular, luteal phase, a nd menses length, 2) variabililty, and 3) anovulation. Results: Heavy smoking (at least 20 cigarettes per day) was associated with nearly four times the risk of short segment (less than 25 days) as was non smoking (adjusted odds ratio 3.8, 95% confidence limits 1.1, 12.7). Mean se gment length was on average 2.6 days shorter with heavy versus no smoking ( 95% confidence limits 0.14, 5.0), due almost entirely to shortening of the follicular phase. Women who smoked an average of ten or more cigarettes per day had significantly more variable segment and menses lengths than nonsmo kers. Based on small numbers, the data suggested that with greater smoking, there was a possible increased risk of anovulation and short luteal phase. Segments of exsmokers with ten or more pack-years of exposure were more li kely to be short and have shorter luteal phases than those of never smokers . Conclusion: The effects found in this study of smoking on the menstrual cyc le might explain in part associations of smoking with other reproductive en dpoints, such as subfecundity and early menopause. (C) 1999 by The American College of Obstetricians and Gynecologists.