New research from US scientists, based at the Columbia University School of Public Health and the New York Psychiatric Institute, suggests that woman who become pregnant by older men are at greater risk of miscarriage. Results indicate that as the male partner ages there is a steady increase in rate of miscarriage.
The study of nearly 14000 women who were pregnant in the 1960s and 70s found that the risk of miscarriage to expectant mothers was 60 per cent higher when the father was aged 40 or over compared to when he was 25-29 years old.
Age made a difference even for men in their 30s. The risk of losing the baby was also about three times greater when the man was aged between 35 and 39 years of age than if he were younger than 25.
This finding was independent of the woman's age and is not explained by other factors such as diabetes, smoking, or previous spontaneous abortions.
The research appears to confirm that men have biological clocks as well as women, and that their chances of having a healthy baby reduce as they get older. Another recent study found that a man's ability to have a child fades after the age of 40, similar to a woman's fertility decline after age 35. Such findings add to the growing realisation of the importance of paternal characteristics for successful reproductive outcome.
'There has been a tremendous amount of research on women, and how their characteristics affect pregnancy outcomes. Of course, women's importance and centrality to pregnancy cannot be overstated. However, scientists seem to have forgotten that men are equal partners in reproduction, and their influence should be studied to the same degree. Our group has focused on men's influence on the health of their offspring, and we have made some fascinating discoveries,' said Dr Karine Kleinhaus who led the study. She added: 'As child bearing is increasingly delayed in Western societies, this study provides important information for those who are planning their families'.
It has already been shown that older men have more abnormalities in their sperm and are more likely to have children with birth defects. Previous research has suggested that the chance of a baby having Down syndrome increase by 11.5 per cent for every ten years older the father is. The American Society for Reproductive Medicine has set an upper age limit of 40 years old for sperm donors because of the increased risk of genetic abnormalities in the offspring of older fathers.
The researchers point out that, despite this generally higher miscarriage rate, older paternal age may only slightly raise the risk to any one couple. The findings were reported in the journal Obstetrics and Gynaecology.