The likelihood of IVF success could be down to the length of a woman's telomeres - the segments of DNA that make up the ends of chromosomes - reports Nature magazine. US scientists, based at the Tufts-New England Medical Center in Boston, have shown that women whose eggs have shorter chromosome tips are less likely to produce an IVF baby. Team leader David Keefe hopes that doctors might be able to use the findings to increase IVF success rates, by selecting eggs with long telomeres. He presented the results at the annual American Society for Reproductive Medicine, being held in San Antonio, Texas this week.
Every time a cell copies its chromosomes (bundles of genetic material), and divides to produce new cells, its telomeres become slightly shorter. So telomere length reflects the age of the parent cell - previous studies have linked short telomeres to aging eggs. But the new study is the first to look at the connection between telomere length and the likelihood of IVF success, which is known to decline with age. The team measured the telomeres in 43 spare eggs, donated by women undergoing IVF treatment, and found that their length varied from between 100 up to 19,000 chemical units of DNA. They found that women whose eggs had an average telomere length of less than 6,300 chemical units never produced a pregnancy.
The results could help doctors 'sift through multiple eggs' to find those most likely to produce a pregnancy, says Keefe. The study could also help explain why fertility declines naturally with age, and why some women have difficulty in conceiving. Those with particularly short telomeres might be helped by searching for their few eggs that have longer telomeres, or by using an egg donor.