Blood Type O May Hurt Fertility Study links blood type A to higher egg count, better eggs By Matt Cantor, Newser User Posted Oct 25, 2010 7:11 AM CDT 2 comments Comments Blood type O may make conception more difficult, a study suggests. (Shutterstock) (Newser) – Women with type O blood may have more difficulty conceiving a child as they get older, a new study suggests. Researchers tested a group of 560 women seeking fertility treatment whose average age was slightly under 35, and found that those with type O blood had fewer and poorer-quality eggs than other women. Type A women, meanwhile, had more and better quality eggs, the Daily Telegraph reports. Type O women were found to be more likely to have higher levels of follicle stimulating hormone; fertility experts link elevated FSH levels to lower egg counts. “Those with blood type O were twice as likely to have an FSH level over 10”—at which point it is considered raised—“than those with blood types other than O,” said a researcher. “We found that women with the A blood group gene were protected from this effect." The findings could indicate that women with type O blood should try to get pregnant earlier rather than later.