Blood type O and early infertility may be linked
It looks like the most common blood type may also be linked with higher infertility, but that would only apply to women who are at risk for early ovarian decline. A study out of the Yale University School of Medicine suggests that there may be something about the molecular biochemistry of type O blood that predisposes vulnerable women to infertility.
Most women experience some ovarian decline in their late thirties to early forties, a change that is often reflected in elevated levels of follicle stimulating hormone (FSH). The hormone peaks each month at ovulation, signaling the ovaries to release an egg. Once an egg is released, the FSH levels go down again. If an egg is not released, however, the FSH remains high, presumably in a continuing attempt to stimulate the ovaries.
Women with ovarian decline typically show elevated levels of FSH, and that is true of women in their forties as well as younger women who develop diminished ovarian reserve. They constitute a small minority of women with infertility problems; nevertheless, such a development can be devastating for an individual who is in her early thirties and who may have assumed she had many years of fertility before her.
Now, study author Lubna Pal says that early-onset decline may be more prevalent in those with type O blood. She cautions, however, not to panic if you are a type O: "I don't want the message to be that women in the healthy population should be petrified that their blood type may predict compromised fertility," she said. The crucial point is that having type O blood does not predict infertility. Most women with type O blood remain fertile. The point of the study is that of the women who do experience early ovarian decline, there is a greater prevalence of those with type O.
Pal and her colleagues studied the FSH levels of 544 women, whose average age was 35, seeking fertility help in Connecticut and New York. After taking into account the effects of age, they discovered that women with blood type O were twice as likely as those with blood types A and AB to have FSH levels high enough to indicate they had diminished ovarian reserve.
Women with blood types A and AB were generally less likely than others to have FSH levels indicating diminished ovarian reserve, the study showed. There were too few women with blood type B in the study for the researchers to determine statistically if their ovarian reserve was affected.
Because Pal's study included only women seeking fertility treatment, she cautioned that the findings of her study do not apply to the general population. However, "having said that, we have enough reasons to be worried about high FSH levels in someone who's not infertile," she said.
That’s because elevated levels of FSH in a young, fertile woman could be a warning sign of impending infertility challenges not too far down the road. For such women, Pal would recommend a full fertility assessment.
And remember, lifestyle choices are almost as impactful of fertility as blood type. Eating a healthy, balanced diet, regular exercise and weight maintenance are also very important factors in fertility.
The study was published June 26 in the journal Human Reproduction.