A woman's hands forming a heart symbol on belly with egg cell.Egg quality is such a huge part of a woman’s fertility. Regular ovulation of a healthy egg is one of the biggest factors involved in getting pregnant. Many women, however, learn that their eggs have chromosome errors. But why do these errors occur, and is there anything women can do about it?

Here are four facts about chromosome errors in women’s eggs.

Fact #1: Chromosome irregularities can occur in up to 60 percent of eggs and is the leading cause of infertility.

A healthy egg has 23 chromosomes, comprising half the number needed for a healthy embryo. The remaining 23 come from the sperm at fertilization. An abnormality in the number of chromosomes in the egg accounts for many cases of infertility, cases of Down syndrome and miscarriages. The majority of these errors are considered accidental, but some cases can be the result of heredity.

Fact #2: Most chromosome errors for eggs affect the ability to divide.

Every cell divides throughout the human body. When division occurs, the two resulting cells should have the correct number of chromosomes. For cells that are not associated with reproduction, this number will be 46, and for reproductive cells, 26. However, irregularities with chromosomes in a cell affect its ability to divide properly. When there is a problem with the cell’s ability to divide, the two resulting cells may have too few or too many copies of the chromosome.

Fact #3: Researchers have identified a cause for some chromosome abnormalities.

Research from the University of Southampton, published in the journal Nature Communications, indicates that the spindle assembly checkpoint (SAC) found in the cells serves as the instructions for proper division that will have the correct amount of chromosomes. When there is a chromosome irregularity, it is often because the SAC is damaged or missing entirely.

Fact #4: Maternal age is a common cause of chromosome abnormalities.

Women are born with approximately 1 million eggs. By the time a woman reaches puberty, she will have 300,000 remaining. Only 300 to 400 of these eggs will be ovulated in her reproductive years. This depletion occurs even when a woman is taking birth control pills, is pregnant or experiences irregular menstrual cycles. Because women are born with all the eggs they ever are going to have, it’s a fact that women’s egg supplies decrease as they age. Furthermore, women do not produce new eggs. Unfortunately, since chromosomal errors increase as you age, women of advanced maternal age are more likely to suffer from these types of irregularities.

When it comes to getting pregnant, few things are more important for the woman’s reproductive health than regular ovulation of a healthy egg. Chromosome errors are natural for all women, usually affecting how the cells divide. Knowing what causes this error is helpful for doctors who need to find the best quality eggs for their patients, putting couples that much closer to having the family they always imagined for themselves.


“How Many Eggs Does a Woman Have?” www.webmd.com. 18 September 2014. http://www.webmd.com/sex-relationships/guide/your-guide-female-reproductive-system?page=3

“New understanding of why chromosome errors are high in women’s eggs.” www.medicalnewstoday.com. 18 March 2014. Web. 9 July 2014. < http://www.medicalnewstoday.com/releases/274158.php>

“Chromosome Abnormalities.” www.genome.gov. Web. 9 July 2014. < http://www.genome.gov/11508982>