What are my chances of getting pregnant in any given month?
For a healthy, fertile couple where both partners are under the age of 35, the chance of getting pregnant straight away is actually pretty low – it’s estimated at around 25 percent per month, if you have regular unprotected sex around the time of ovulation.
If you’re not actively trying to conceive and not planning intercourse to occur around the time of conception, but you are having regular unprotected sex, your chances of getting pregnant drop to just 11 percent per month.
That’s why doctors have traditionally suggested waiting until you have been trying for a baby for a year before starting fertility investigations, although many couples choose to start preliminary investigations after six months, particularly if they are over thirty.
How do the chances of getting pregnant change as I get older?
On average, a woman with no fertility issues will fall pregnant after four months of trying to get pregnant – but from around the age of 21, fertility slowly declines with age until around 35, then declines faster until the age of 40, after which fertility decline is very rapid.
There is much debate between scientists about the odds of conception.
Here is one of the most commonly cited estimates on the percentage chance of conception after one year of trying:
- Age 20: 90% probability
- Age 30: 70% probability
- Age 35: 55% probability
- Age 40: 45% probability
- Age 45: 6% probability
A 2002 study by Dunson et al studied 782 healthy couples in Italy and the USA and found that there was great variability in the chances of getting pregnant on the peak day of conception (two days before ovulation). They estimated that, for a couple who were the same age, the odds of falling pregnant in any one menstrual cycle when having sex on the peak day for conception were:
- Aged 19 to 26: 50% chance in any one menstrual cycle
- Aged 27 to 34: 40% chance in any one menstrual cycle
- Aged 35 to 39: less than 30% chance in any one menstrual cycle, but with a male partner five years older, the chance falls to less than 20% chance in any one menstrual cycle
This research suggested that smoking, sexually transmitted disease history and occupational exposures contributed to lower fertility rates.
Can IVF improve fertility rates for older women?
Increased use of assisted conception treatments by older couples has helped promote the idea that fertility treatments like IVF can postpone the natural decline of fertility.
However, success rates for IVF still mirror those of natural fertility, with reports issued by the US Centers for Disease Control and Prevention (CDC) show that the rate of live births from IVF and similar treatments using the mother’s eggs decreases with age.
The latest figures show that for women under 35, the percentage of live births after one cycle of assisted reproductive treatments (including IVF) was about 45%.
Success rates declined after this age group. For those between ages 35-37 it was about 37%, dropping steadily to just 6.6% for those aged over 42.
But older women can dramatically raise their IVF success rates by using an egg donor; the CDC report states that the chance of a fertilised egg implanting depends on the age of the woman who produced the egg.
Success rates for women, even in their mid-forties, who use a donor egg from a woman in her 20s or early 30s remains above 40%.
Many women have no trouble falling pregnant over 35 or even over forty; but if you’re over 35 and haven’t fallen pregnant after six months, it’s worth talking to your doctor and starting fertility investigations.
What can be done to improve my odds?
Plenty of products, consultants and websites promise to improve your chances of getting pregnant – for a price. But many are rip-offs with no scientific evidence, which prey on the vulnerability of people keen to have a baby.
Here’s some tips on improving your chances of getting pregnant, without paying a fortune:
Reduce your stress levels
There’s a strong correlation between stress levels and fertility. If the main reason you’re stressed is that you want to have a baby, then this is hollow-sounding advice indeed.But there are often ways you can change other stresses in your life; take a holiday; re-think your job or other commitments that might shift down your priority list.
Aim for a healthy weight
Research shows that there is a strong connection between obesity in women and lower fertility. Being significantly underweight for long periods of time can also negatively impact your fertility. Try for a healthy balance!
Improve your diet
While research evidence is inconclusive, some fertility experts swear by a diet of organic foods. It’s your choice whether to go all-out or just keep an eye on your food choices (eating at home and avoiding takeaway is a good start!)
Quit smoking and cut back on the booze
There’s a strong link between smoking and reduced fertility in both men and women; this might be enough of an incentive to help you kick the habit.
You don’t have to become a gym junkie – in fact, it’s better if you’re not – but some regular exercise each day can’t hurt; and if a nice long walk reduces your stress levels and improves your cardio status, it might well help your chances of getting pregnant.
By Fran Molloy, journalist and mum of four
Last Published* December, 2022
*Please note that the published date may not be the same as the date that the content was created and that information above may have changed since.