Background and methodology The ovarian cycles of females living and interacting together may synchronise due to pheromones released from axillary secretary glands, the highest concentration of which is produced in the mid-follicular phase, prior to ovulation. The objective of this study was to find evidence for menstrual synchrony in a group of female students living together and to obtain a correlation between the ability to smell the putative pheromone, 5α-androst-16-en-3α-ol (3α-androstenol), found in apocrine secretions and menstrual synchrony. This cross-sectional study involved 88 students who completed a standard questionnaire and whose sense of smell was measured using ten varying thresholds. The menstrual history, friendship scale and menstrual hygiene score was determined for the participants.

Results A total of 59.1% of the subjects studied were found to have menstrual synchrony. There was no significant association between menstrual synchrony and smelling threshold. However, a significant correlation was found between menstrual synchrony and personal hygiene score (p<0.01).

Conclusions The phenomenon of menstrual synchrony may be related to various factors. The results failed to demonstrate any significant difference between synchronised and non-synchronised subjects in detecting the steroid by sense of smell. However, the odours associated with menstrual blood or vaginal discharge might have an affect on menstrual synchrony.