Smoking and cycle control among oral contraceptive users

Area of Science:

• Reproductive Health
• Pharmacology
• Tobacco Control

Background:

• Cigarette smoking exhibits antiestrogenic properties.
• Understanding the impact of smoking on hormonal contraception is crucial for patient counseling.

Purpose of the Study:

• To investigate the association between cigarette smoking and breakthrough bleeding in oral contraceptive users.
• To determine if smoking status affects cycle control in women using combined oral contraceptives.

Main Methods:

• Analysis of three open-label, randomized clinical trials.
• Inclusion of 16,506 cycles from 2956 oral contraceptive users.
• Controlled for oral contraceptive use recency, consistency, and progestin component.

Main Results:

• Smokers experienced significantly higher rates of spotting and bleeding compared to nonsmokers.
• Smokers were 47% more likely to have spotting or bleeding over six cycles.
• Heavy smokers (≥16 cigarettes/day) were nearly three times more likely to experience bleeding by the sixth cycle.

Conclusions:

• Cigarette smoking adversely affects cycle control in oral contraceptive users.
• Smoking may increase estrogen catabolism, leading to breakthrough bleeding.
• Impaired cycle control due to smoking may reduce oral contraceptive adherence and increase unintended pregnancy risk.