According to a new study, a woman’s monthly period is tied to the difficulty of quitting smoking.

The study, published in Psychiatry Journal, examined 34 men and an equal number of women who were habitual smokers, which was defined as smoking at least 15 cigarettes per day.

Each participant was administered an MRI and the researchers discovered that while it was equally difficult for men and women to kick nicotine, women were prone to stronger cravings at specific times of the month.

Study author Adrianna Mendrek, a neuroscientist at the Institut universitaire en santé mentale de Montreal, said the MRI’s revealed that women felt more uncontrollable urges to smoke during the follicular phase, the first part of a woman’s menstrual cycle when she begins her period. 

“Hormonal decreases of [estrogen] and progesterone possibly deepen the withdrawal syndrome and increase activity of neural circuits associated with craving,” said Mendrek.

Mendrek noted that the frontal, temporal, and parietal lobes of a woman’s brain are more active during the follicular phase compared to the luteal phase, the second part of a woman’s cycle when ovulation begins. She conjectured that, at least from a biological standpoint, it would be easiest for women to quit smoking sometime after the luteal phase.

“The data do suggest that it may be easier for women to quit during the mid-lutael phase rather than in early follicular phase, but the psychosocial factors are probably much more important here,” said Mendrek.