The success of IVF (in vitro fertilisation) in women under the age of 40 may be affected by the age of their male partners, suggests a US study.
The chance of having a baby through IVF fell for these women with increasing age in their male partner.
'Our study found an independent effect of male age on the cumulative incidence of live birth,' said Dr Laura Dodge at Beth Israel Deaconess Medical Center and Harvard Medical School in the USA.
Female age is known to be the dominant factor in predicting a couple's chance of conception, but few studies have explored the impact of male age. This new study analysed nearly 19,000 cycles of IVF in 7753 couples in the Boston area. While the age of the male partner had no effect on IVF success in women aged 40-42, it had a significant influence in younger women, the team found.
For example, couples where the woman was under 30 and the man aged 40-42 had a 46 percent chance of having a baby through IVF, compared with a 73 percent chance if the man was aged 30-35.
'Generally, we saw no significant decline in cumulative live birth when women had a male partner the same age or younger,' said Dr Dodge, who will present the results to the European Society for Human Reproduction and Embryology's annual conference in Geneva, Switzerland on 4 July.
The reasons for decreasing IVF success with male age are unknown, but Dr Dodge noted that with natural conception, older male age is associated with fewer pregnancies and increased time to pregnancy. Mechanisms are unclear, but may include increased DNA damage in sperm and epigenetic alterations in sperm that affect fertilisation and implantation.
Professor Nicholas Macklon at the University of Southampton said of the findings: 'It may help women to encourage their male partners to get a move on.'