The Biological Clock: Faster than Once Thought

Researchers in the United States and Italy say their study is the first to show a drop in female fertility below the age of 30.

The study’s results do not mean that older couples will not be able to conceive, it just might take them longer.

Researchers studied 782 healthy Italian couples to determine the impact of age on conception. They published their findings in the journal Human Reproduction.

"Although we noted a decline in female fertility in the late 20s, what we found was a decrease in the probability of becoming pregnant per menstrual cycle, not in the probability of eventually achieving a pregnancy," Dr. David Dunson of the National Institute of Environmental Health Science in North Carolina, USA told Reuters.

The doctors estimated the chances of conception during the so-called "fertile window" in the woman’s monthly cycle for couples in three age groups.—19-26, 27-34, and 35-39.

The youngest women had a one in two chance of becoming pregnant in any one menstrual cycle. That fell to 40% in the 27-34 year-olds.

For those in their late 30s it dropped to less than 30 percent. If the woman’s partner was five years older, those chances fell a further 10 percent.

Not Just a Female Problem

Male fertility also begins to wane with age, researchers said.

"Fertility for men is less affected by age," said Dunson, "but shows significant decline by the late 30s."

But even within each group, researchers found variation in conception rates among healthy couples that could not be explained by age.

Slowing It Back Down

Even as this study shows a faster clock, Australian researchers are working on a technique that could extend women’s fertility until they are in their late 40s and 50s.

Scientists at Melbourne’s Monash University are trying to manipulate the protein in the body that releases human eggs. They want to slow down the number of those eggs released each month.

The idea is that be slowing down the process, more eggs would be retained and fertility preserved longer. If the technique is perfected, researchers say it will open the child-bearing window another 10 years for women.