Age has a significant impact on fertility and the chance of having a healthy baby. In women, fertility starts to decline slowly in their early thirties and this decline speeds up after 35. The monthly chance of pregnancy for couples in which the woman is 35 or younger is about 20% and 80-90% achieve a pregnancy within 12 months. By age 40, the monthly chance has dropped to 5% and only 50% of couples conceive within 12 months.
While most people might think age only affects female fertility, there is growing evidence that sperm quality decreases as men age, starting at around 45. Women with male partners aged 45 or older are almost five times more likely to take more than a year to conceive compared to those with partners aged in their twenties.
Age-related fertility decline is a cause of involuntary childlessness or having fewer children than planned. To overcome age-related infertility, people often turn to assisted reproductive technologies such as IVF for help.
But unfortunately, as with spontaneous conception, the chance of having a baby with assisted reproductive technologies decreases with increasing parental age. In 2014, more than a quarter of women (26%) and over a third (35%) of male partners who accessed assisted reproductive technologies were aged 40 or older.
In that year, the chance of a live birth per started treatment cycle was 25.6% for women under 30, but only 5.9% for women aged 40-44.
Increasing age of parenthood isn’t just due to women delaying childbearing
In part, as a result of increasing age at first birth, Australia’s fertility rate, which is the average number of babies born to a woman throughout her reproductive life, is at an all-time low.
Existing research – and public discourse – relating to childbearing focus almost exclusively on women. Declining fertility rates are often portrayed as being the result of women delaying childbearing to pursue other life goals such as a career and travel.
But studies we have conducted indicate it’s the lack of a partner or having a partner who is unwilling to commit to parenthood that are the main reasons for later childbearing and involuntary childlessness.
We also know, contrary to the common stereotype that parenthood is more important for women than for men, that men desire parenthood as much as women do. So how do men influence the age of childbearing and fertility rates?
To better understand men’s role in childbearing decisions and outcomes we conducted a survey of 1,104 randomly selected Australian men aged between 18 and 50 years.
What men know about fertility
We found that most men (90%) wanted at least two children. Almost all (97%) said they had enough knowledge about reproduction for their needs but when they were asked at what age fertility starts to decline most underestimated the effect of age on male (55%) and female (68%) fertility.
Responses to a question about the chance of having a baby with IVF for women in their late thirties or early forties showed that more than half of the men (60%) believed assisted reproductive technologies can overcome age-related infertility. We also asked up to what age the men thought it was acceptable for a man to have children and most (62%) thought it was acceptable for men aged over 50 to father a child.
Childbearing and parenting are shared endeavours, and this study suggests that men’s lack of knowledge about fertility and attitudes towards acceptable ages for parenthood might put them at risk of missing out on ever having kids, or having fewer children than they wanted to have.
Attempts to increase men’s knowledge about the limitations of fertility may increase the likelihood that men (and women) achieve their parenthood goals.
The bottom line is, for men who have a partner and want to have children, the “right” time to become a dad is sooner rather than later.
Senior Research Fellow, Jean Hailes Research Unit, School of Public Health & Preventive Medicine, Monash University and Research Fellow, Monash University