A local study has found that older fathers increase the risk of miscarriage in women
When it comes to fathering a child, time is not always on a man’s side.
More studies are showing that men, too, have biological clocks, and they may start ticking at around 40 years old, said Dr Tan Thiam Chye, Consultant, Department of Obstetrics and Gynaecology, KK Women’s and Children’s Hospital (KKH), who recently spearheaded a Singapore study which showed that advanced paternal age increased the risk of miscarriage.
The study monitored 139 women with threatened miscarriage (those with vaginal bleeding during early pregnancy) over a period of 16 weeks. It found that fathers over 40 years old added an eight-fold risk of miscarriage, compared to fathers between 30 and 40 years old.
The quality of a man’s sperm will deteriorate with time, causing damage to its DNA and leading to a higher chance of miscarriage in the woman.
For fathers between 30 and 40, the risk of miscarriage was about four times higher than fathers between 20 and 30 years old.
The reason for the higher risk of miscarriage is linked to the decline in quality of sperm in older men, said Dr Tan, who is also an Assistant Professor at Duke-NUS Graduate Medical School (Duke-NUS).
“Having noted an increased risk of foetal loss with a paternal age greater than 40, we can infer that the biological clock ticks not only in the woman, but also in the father-to-be,” said Dr Tan.
The study, conducted jointly by KKH and Duke-NUS, contributes to the growing amount of evidence, which points to the fact that the age of the father affects not just fertility, but the health of the pregnancy and baby too.
While research on the impact of women’s age on childbearing is well known, fewer studies have been done to determine the role that paternal age plays, said Dr Tan.
For women, their biological cut-off point is well defined at age 35. But for men, this could be at around 40 years old, said Dr Tan.
“For a man above 40, we’ll be more worried that there could be a possibility of paternal DNA changes, and this can predispose his offspring to congenital problems or even lead to miscarriage,” he said.
How a man’s clock ticks
Like women, men experience changes to their bodies and reproductive systems as they age, and this impacts their fertility and the health of their offspring.
While sperm production is unending in men, their production and transportation structures weaken over time, said Dr Matthew Lau, Associate Consultant, Department of Reproductive Medicine, Division of Obstetrics and Gynaecology, KKH.
“For instance, the sperm production slows down and the reproductive tubes narrow. Beyond this, the prostate and urinary functions also change,” said Dr Lau.
The male sex function declines too. Over time, men’s testosterone levels dip, they experience lower sex drives and are more susceptible to sexual problems like erectile dysfunction, said Dr Lau.
“Erectile dysfunction is closely linked to blood supply problems. When people get older, and if they have diabetes or high cholesterol levels, they are likely to have blood vessel problems. If such problems affect the penis, it leads to erectile dysfunction,” he added.
In older men, sperm quality also becomes poorer. As sperm is produced at a slower rate, the risk of exposure to toxins through factors such as infection and smoking is higher. This can damage the DNA of the sperm, said Dr Lau. If the sperm’s DNA is more than 40 per cent damaged, there is a higher chance of miscarriage, he said.
Studies have also shown that older fathers increase the risk of genetic problems such as autism and dwarfism in their children.
Environment and lifestyle matters
Besides the ageing process, a man’s lifestyle can also upset his sperm count and quality. Factors like stress, smoking, drinking and working in highheat environments have been shown to lower sperm count and quality in men, said Dr Tan.
Already, he noted that male fertility is falling worldwide, and Singaporean men are not spared. “Normally, in a semen sample of a millilitre, there should be more than 15 million sperm. But in some samples that we see, there may only be one sperm.”
Race against the clock
With the current trend of men and women marrying and having children later in life, is it all doom and gloom for older fathers-to-be?
“Normally, in a semen sample of a millilitre, there should be more than 15 million sperm. But in some samples that we see, there may only be one sperm.” Dr Tan Thiam Chye, Consulta nt, Department of Obstetrics and Gynaecology, KK Women’s and Children’s Hospital
Dr Lau does not think so. He said that as long as a man continues to produce sperm and is able to have normal sexual intercourse, there is still a possibility of him fathering a child. A fertile female can also compensate for a lower male childbearing potential. Reproductive technologies like intrauterine insemination (IUI) and in-vitro fertilisation (IVF) are also available to help couples who have problems conceiving.
But with the risk of birth issues increasing with advanced paternal age, doctors have advised those who want to become fathers to start planning earlier.
Dr Tan said: “Men aged 40 and above who are thinking of having children should not delay any longer.”