Muramasa via wikimedia commons. Women on the pill may pay less attention to a man's looks, but change their mind when coming off.

When choosing partners, pill goggles may be more effective than beer goggles. Men who would otherwise be seen as unattractive look like a good candidate to women who are taking hormonal contraceptives. If a new study published in the Proceedings of the National Academy of Sciences is to be believed, the problems start when, once in a relationship, women go off the pill and decide they actually care about looks.

The idea that hormonal contraceptives change women's taste in partners is not new. Past studies have concluded that heterosexual women's tastes change during their menstrual cycle, being more interested in masculine-looking men when ovulating and prioritizing other things during the rest of their cycle.

The common, unverified, explanation for this is that masculine good looks are associated with “good” genes that benefit the children. On the other hand, it is posited, men whose features don't fit the stereotype make more caring partners and parents. So evolution has favored women who procreate with someone attractive, but settle down with someone who cares.

The reductionist nature of this theory has been criticized, and contradictory results have been published, but the idea has inspired a slew of further research, some finding that women whose ovulation is suppressed are less interested in rugged good looks.

The new study takes a longer term look at this process to see what happens if women change their pill usage after entering a relationship.

"Given that women [tend to] prioritize attractiveness differently when they are on versus off [hormonal contraceptives], I thought that going on or off [hormonal contraceptives] should affect how happy they are with their partner,” Florida State University graduate student Michelle Russell told Live Science.

Russell asked women about their satisfaction with their relationship, dividing her sample based on contraceptive use at the start of the relationship and after settling down.

The group who had been on the pill at the start of the relationship, and were now off it, showed differences based on their partners' looks. Among these, women who married men that were rated below average physical attractiveness by an independently “trained” panel were the least satisfied in the study. Those who quit the pill after marrying men judged good-looking were particularly likely to be satisfied with their partners. No effect was observed from going on the pill.

The study is open to plenty of criticism. Only 48 couples were followed for the full four years, and another 70 for one year. Once split by contraceptive use and attractiveness, the sample size in each category is tiny. Moreover, women having less sex might have been more likely to stop using the pill, reversing the direction of causality.

Still, Russell postulates that once women stop taking the pill, they become more focused on men's looks and those who start to notice their partner isn't attractive become disappointed. A previous study using a different design also found that women who went off contraceptives were less sexually satisfied, but also found that the relationships lasted longer in those cases.