Super-fertile women, who conceive more easily than others, may also be statistically more likely to miscarry, shedding light on understanding the mechanics of why pregnancy occurs in some but not others and seemingly dispelling some long-held ideas of the reasons behind why some conceptions occur.
Super-fertile women were the focus of a recent study that indicates that while it was previously thought that miscarriage was a rejection by the mother based on immunological causes, another factor may actually be at work. The study on the biology of implantation was published Friday in the journal PLoS ONE, suggesting that super-fertile women may actually lack the ability to block a pregnancy that is inadvisable and that the circumstance may lead to more miscarriages of pregnancies that could not be sustained to term.
In the US, about 10% of pregnancies result in miscarriage, and about half the time, doctors can pinpoint a cause. But in the study, women from the 1-2% of American couples who have suffered recurrent miscarriages were studied and compared with women who did not experience recurrent miscarriages.
In the former group, both high and low-quality embryos were accepted by their uterine cells, while the latter’s cells rejected the embryos that were not suitable for development. Co-author of the study Nick Macklon explains:
“Many sufferers of recurrent miscarriage feel that they failing as mothers, because they seem to reject lots of pregnancies. In fact, the opposite may be the case: They are super-fertile, allowing embryos which would normally be allowed to implant and survive long enough to show up as a pregnancy, before miscarrying.”
Jan Brosens of the University of Warwick explained:
“This is important as — for the last 60 years— the whole field believed that miscarriage is the consequence of maternal rejection of the fetus because of immunological differences.”
Researchers say that the study could help develop ways to prevent and treat miscarriage, but will also serve to reassure women who have suffered several miscarriages that the circumstance is likelier to have been unavoidable.