Business woman covering her mouth in nausea.A woman’s fertility is tied to her ovarian reserve. A recent study published in Human Molecular Genetics this year discovered that all eggs are not created equal. This new study, headed by Professor Kui Liu from the University of Gothenburg, Sweden, indicated that women’s eggs come in two waves: the first wave and the adult wave.

The team studied mice, genetically modified, to see if the eggs that are produced before the mouse reaches sexual maturity are the same as the ones that are produced after sexual maturity. What they found is that the first eggs helped instigate puberty and provided eggs that helped the mice transition from adolescence into the adult years, while a second wave of eggs, which remains dormant until they are triggered by the mice hormones, are the ones they ovulate throughout the rest of their lives.

This is the first study to conclusively indicate that eggs have two different types. Although the study was done on mice, Professor Liu and their team are reasonably confident that the same will be true of human eggs as well.

Women are born with their egg supply and produce no more in their lifetime. It isn’t until she begins her menstruation cycle that eggs are actually released by the ovary, but it doesn’t change the fact that eggs are always expiring every month. The good news is that most women are born with millions of eggs in their reserve.

A few years ago, a study from the United Kingdom declared that by the time a woman reaches the age of 30, 90 percent of her ovarian reserve has been depleted. The headline was shocking to many women who understood that at 30 they still had plenty of time to start their families. While 10 percent is still plenty of eggs to conceive, and in many cases number in the several thousand range, the study reminded women to bear in mind their age and the ovarian reserve they were working with for conception when planning for their families.

There is no method to determine an exact number of eggs a woman has left. There are tests, however, that can indirectly help a doctor make an educated guess. Some will take an ultrasound that will measure the volume of the ovaries to determine the amount of eggs left in a woman’s reserve. Some doctors will also do a blood test to check for hormone levels in the bloodstream to get an indication of how many eggs are left.

The Gothenburg study will have implications on how doctors treat women with infertility as a result of their egg reserve. In particular, the findings are likely to affect treatment for premature ovarian failure (POF), as well as other conditions that affect the ovaries. More specifically, the findings may change how they target each of the two egg populations as a result of these conditions.

The ovulation of a mature egg is the foundation of women’s fertility health. Because of this fact, everything that science learns about eggs and the ovarian reserve can help women and their doctors make the best decisions for their treatment options when they are in fertility treatment. It could be the information that science uncovers today gives us the answers to the fertility challenges we will have tomorrow.

“Eggs of Adolescent girls are different from those of adult women.” 28 February 2014. Web. 31 March 2014. <>

Fortuna, Roger, et al. “For Women Who Want Kids, ‘the Sooner the Better’: 90 Percent of Eggs Gone by Age 30.” 29 January 2010. Web. 31 March 2014. <>