Ovarian reserve testing, which is performed to measure how many eggs a woman has left, is at present the most common test to assess fertility. Now experts say its results may not be an accurate predictor, and that it’s the quality of the oocytes that is the key factor.
Women are born with a finite number of oocytes, which gradually dwindles with age. Up until now, the accepted method of evaluating one’s chances of conceiving was by assessing the number of eggs she had left. However, a study recently published in JAMA claims that it is actually the quality of the eggs that matters, and a diminished ovarian reserve doesn’t necessarily lead to fertility issues.
Experts examined 750 women between the ages of 30 and 45 who had no history of infertility, splitting them into two groups, depending on the amount of oocytes they had. A follow-up performed a year later showed that women in both groups were equally likely to fall pregnant and give birth. They now believe that the egg’s quality, which is determined by its probability of becoming an embryo and implanting, is a much more important infertility predictor than the quantity of oocytes.
The results are good news for women with low ovarian reserve, but they don’t, however, mean that the odds of getting pregnant do not drop with age, as the quality of eggs also tends to decrease with time. For example, while, on average, roughly one third of a woman’s eggs are of good quality when she’s 25, only about every tenth oocyte fits the criteria by the time she’s 40.