Women who quit smoking in the days preceding their menstrual cycle have a better chance of succeeding, according to researchers who say that sex hormones like estrogen and progesterone may help remove nicotine from the blood faster.

The Daily Mail reported April 21 that researchers from the University of Minnesota studied 200 women, half of whom were instructed to quit smoking during the "follicular" stage of their menstrual cycle -- the span between the end of their period and ovulation -- and half of whom were told to quit during the "luteal" stage -- the span between ovulation and the beginning of the next menstrual cycle.

The researchers found that about 40 percent of the women in the luteal group had remained abstinent after 30 days, compared to 20 percent in the follicular group. "Our findings support an important role for ovarian hormones in smoking cessation," the authors wrote.

The study was published in the May 2008 issue of the journal Addiction.