It's a biological fact that as women and men age, their potential to have children decreases, although the exact time when this starts to happen can vary among individuals.
We all know someone who had a healthy baby in their late 30s or early 40s. But of all people who try for a baby at a later age, many will not have the baby they hoped to have.
Across a population, women younger than 35 and men younger than 40 have a better chance of having a child than people who are older. This is true for natural pregnancies and for pregnancies conceived through assisted reproductive treatments such as IVF (in-vitro fertilisation).
The combination of both partners' ages determines the likelihood of pregnancy.
IVF is a good back-up option for having a baby later in life.
Getting pregnant both naturally and with IVF becomes more difficult with age.
Why? Because age affects eggs and sperm
Younger women have more and healthier eggs than older women.
Younger men have more active and better-quality sperm than older men.
Age and eggs
A woman is born with all the eggs she will ever have. As she ages her eggs age with her and their number and quality reduces over time. This is why her chance of having a baby also reduces over time, especially for women older than 35 years of age.
This information can be difficult for women who, for whatever reason, are not ready in their 20s or early 30s to start a family.
Age and sperm
Men younger than 40 have a better chance of fathering a child than those older than 40. The quality of the sperm men produce seems to decline as they get older.
Most men make millions of new sperm every day, but men older than 40 have fewer healthy sperm than younger men. The amount of semen (the fluid that contains sperm) and sperm motility (ability to move towards an egg) decrease continually between the ages of 20 and 80.
Women’s age and getting pregnant
For individuals and couples there can be many reasons why life gets in the way of starting a family. Not having a partner, career, finances, housing, travel, not feeling ready, whatever the reason, many find that it’s just not the right time to have a baby.
Sometimes people find themselves trying to get pregnant later in life, when it can be a lot more difficult.
For women, the easiest time to get pregnant is before the age of 30. As women get older, it takes longer to conceive and the chance of having a baby decreases.
- women are most fertile before the age of 30
- after 30, women's fertility starts to decrease
- after 35 fertility declines more significantly
- by 40, a woman’s fertility is about half the level it was before she was 30.
A study compared women’s ability to conceive, in different age groups. It showed that, compared to women aged 30-31, the chance of conceiving was:
- 14 percent lower for women aged 34-35
- 19 percent lower for women aged 36-37
- 30 percent lower for women aged 38-39
- 53 percent lower for women aged 40-41 years.
Women younger than 30 have about a 20 percent chance of getting pregnant naturally each month. By age 40, the chance of pregnancy is about five percent each month.
Men’s age matters too
We’ve all heard about men in their 80s and 90s fathering children, but this is rare. A father’s age also affects the chance of a couple getting pregnant. It takes longer for partners of men older than 40 years to conceive.
Assuming a woman is younger than 25; if her partner is also younger than 25, it takes an average of five months to get pregnant. If her partner is older than 40 years, it takes around two years, and even longer if he is older than 45.
Also, the risk of miscarriage is higher for women whose male partner is older than 45 , compared to men younger than 25 years of age.
For couples having IVF, the chance of having a baby is higher if the man is younger than 41 years of age.
Pregnancy and birth risks
Because of the changes that happen in eggs and sperm as we age, including damage to genetic material, children of older parents have a slightly higher risk of birth defects and genetic abnormalities. The risk of mental health problems and autism spectrum disorder is marginally higher in children of fathers older than 40 than in those with younger fathers.
It is estimated that the risk of having a baby with a chromosomal (or genetic) abnormality is approximately one in 400 for a woman aged 30 and one in 100 for a woman aged 40.
The risks of miscarriage and complications in pregnancy and childbirth are higher for older women than for younger women.
It’s important to remember that although the risk of health problems increases with age, most babies are born healthy, whatever their parents’ age.
If you want to have a baby (now or sometime in the future), understanding how age affects your chances of getting pregnant and having a healthy baby is really important. Talking to your local doctor (GP) or visiting a family planning clinic about your plans for having children may help you understand how you can protect your chances of having a baby.
If you are in a relationship, having a conversation early about if and when you’d like to have children can help you and your partner understand each other’s thoughts about having a family.
Improving your chances
The good news is there are ways to increase your chance of having a baby, whether you’re single, in a relationship, male or female.
What can you do now?
Even if you’re not planning to have a baby soon, making some healthy choices now increases your chances of having a baby in the future.
A healthy lifestyle boosts your chances of having a baby. Find out more about what you can do:
Sometimes getting pregnant is difficult
No matter how healthy you are, or what age you are, sometimes it is difficult to get pregnant.
If you have tried for 12 months or more (six months if you’re a woman older than 35), it’s time to talk to your doctor about your options. The best place to start is to see your general practitioner (GP). You might like to complete the Healthy conception tool, and take your results, and your partner’s results (if you have a partner), with you to discuss with your doctor.
MYTH: Women can have children at any age because many women have babies in their 40s.
FACT: Age is the most important factor affecting a woman’s chance of conceiving and having a healthy child. Many women in their late thirties and early to mid-forties give birth to healthy babies, but many in these age groups are not able to have a baby.
What about IVF?
Some people may think that assisted reproductive treatment such as IVF is the answer to postponing pregnancy to a later age.
IVF can help people with infertility have a family but the technology cannot make up for the natural decline in fertility that happens as women and men get older.
Chances of having a baby through IVF
As women get older, IVF success declines: 40,696 women in Australia and New Zealand undertaking IVF (fresh cycles using their own eggs) and the success rates (live delivery per initiated cycle).
These figures apply to women who use their own eggs. If an older woman uses eggs from a younger donor, her chance of having a baby is the same as that of a woman in the donor’s age group.
- Australian Institute of Health and Welfare. Australia’s mothers and babies 2015—in brief. Canberra: AIHW; 2017.