"They say that opposites attract. But it seems the Pill may be preventing women sniffing out men who are opposite enough...But researchers found that the Pill disrupts a woman's power to recognise the aroma of a suitable partner."
So what does the study do? It looks at a bunch of women, none of whom were on the pill, but some of whom were thinking about taking it. So they got these women to smell the shredded sweaty shirts of men with either genetically similar or dissimilar MHCs:
"Almost 100 women then sniffed the shirts and gave their opinions on the 'pleasantness' and ' desirability' of the odour twice over a three-month period. Many started taking the Pill during the experiment - and their opinions of the smell of the T-shirts changed...Researcher Craig Roberts said: 'The results showed that the preferences of women who began using the contraceptive Pill shifted towards men with genetically similar odours.'"
"Saddled with the wrong man - someone who in scientific terms has similar genes - she may find it hard to become pregnant and any children she does have may have a lower resistance to infection.
What is more, when she stops taking the Pill and her sense of smell returns to normal, she's more likely to fall out of love, the Liverpool and Newcastle universities research suggests."
The only significant finding was an interaction on an ANOVA where women on the pill showed a reduction in the amount they favoured MHC dissimilar odours, but there was no statistically significant difference between women on the pill and women not on the pill in the degree to which they favoured genetically dissimilar men. The interesting finding is that women not yet on the pill, but who intended to go on the pill seemed to favour MHC dissimilar men more than other women (presumably this wasn't statistically significant) and this is what is driving the interaction (the preference for dissimilar men normalises back to being like other women after they are taking the pill (see the figure, average odour 'desirability' for MHC dissimilar men minus MHC similar men, white bar represents first rating {before women started the pill} and the grey bar the second rating {with women in the pill group having started the pill}).
So it is pretty unlikely that taking the pill will cause problems becoming pregnant or children with a lower resistance to infection, since women not on the pill don't seem to favour MHC dissimilar odours (and thus men?) anyway, and women taking the pill don't show any difference in their preference for MHC dissimilar men compared to women not on the pill anyway.
The Mail does carry a contrary opinion from Professor Bill Ledger (Sheffield University) who wonders whether the smell of sweat is likely to overide the 'intellectual and emotional feeling' of a relationship but curiously doesn't attack the methodology of the paper. I wonder whether this is another example of embargoed press releases where those commenting on the paper don't actually get to see it and point out the obvious flaws.