One in five men in Switzerland is over 40 when he becomes a father, and this could be a risk factor for the baby. (SRF/swissinfo.chexternal link)
A study published in Nature magazine shows older fathers transmit a higher number of mutations to their children than older mothers. But they make up for it in their ability to nurture.
Scientists at deCODE genetics in Iceland discovered that a 40-year-old father is approximately twice as likely to conceive a child with autism or schizophrenia than a man half his age.
Women are born with all their eggs, but male sperm is constantly replicating. Each time sperm replicates there is a chance for a mutation in the DNA to occur.
As men age, they are also exposed to numerous environmental toxins which have been shown to cause DNA mutations in sperm.
But there are definite advantages to becoming a father later. Older dads are often calmer, more patient and less career-orientated. They are also more likely to be financially stable.
Women are often criticised for delaying parenthood until their late thirties, but they have a whole raft of tests available to monitor the baby’s progress before the birth. No such prenatal tests exist for male sperm.