Far be it from me to be skeptical of such a study, however.
When planning our family (three healthy little girls & no pre-eclamptic problems), I'd heard all about the dangers of pre-eclampsia and saw a study that insinuated this from an article in Cosmopolitan. It pointed out that mothers-to-be NEED all the sperm from their MATE that they can get in their bloodstream in order to get his genes into her system so that the fetus gains a genetic ballance from both parents. Thus, the importance that all of the sperm come from the same male. No need to go getting slutty, girls, it only works with the one man who is fathering the child. Getting slutty and mixing male genes will only confuse your system and is likely to cause problems in pregnancy rather than prevent them.
Fortunately, the mother has two choices of how to get that into her bloodstream, as either intercorse or oral will do the trick (Hence, the more "Earthy" terminology, "Up the snatch or down the hatch")...She doesn't have to wear herself out in the sack. She just needs to get all she can get and as often as she can get it from one man.
Now, for those playboys out there who think this study was their key to con women into the sack, how does it sound when it means you're only getting it if it's ONE WOMAN allowing you??? Sounds a bit like ""COMMITMENT", doesn't it?