If you’re trying to start a family, or you hope to have children one day but you’re not currently in a position to do so, you’ve probably had people tell you that you need to start before you’re 35, because once you’re over that age you’ll seriously struggle.

It increases your stress and anxiety to hear that, but is there any truth in it? Exactly how hard is it to get pregnant after the age of 35, and should you keep your hopes up?

Like many things, the answer is more complicated than people make it sound.

35 is no magic number

It’s impossible to draw a line in time and say that after this date, your fertility plummets. Instead, what happens is that your fertility begins to drop gradually from your late 20s. The rate of decline speeds up once you get to 32, and then it speeds up again at about age 37.

By the time you reach the age of 40, your fertility has dropped significantly. It’s still possible to get pregnant, but it might take a lot longer than you expected.

Here are some statistics to explain things more clearly. One large study looked at pregnancy rates for women if they have sexual intercourse on their most fertile day. It found that:

• Women aged 19-26 years had an over 50% chance of conceiving
• Women aged 27-34 have a rate of just below 40%
• Women aged 35-39 have under a 30% chance of getting pregnant, almost half the rate of women aged 19-26.

To put it another away, you have a 25% chance of conceiving each month when you’re in your 20s, but only a 5% chance each month when you’re in your 40s.

That doesn’t mean it’s impossible, only that it’s less likely.

Another way of calculating fertility is by tracking how long it takes for a woman to conceive and give birth. Using this method, it was estimated that:

• 75% of 30 year-old women conceive within 1 year, and 91% within 4 years.
• 66% of 35-year-old women conceive within 1 year, and 84% within 4 years.
• Only 44% of 40-year-old women conceive within 1 year, and just 64% within 4 years.

Given these statistics, the American Society of Reproductive Medicine (ASRM) recommends that you should begin evaluation for infertility if you haven’t become pregnant within 12 months of unprotected sex if you’re under 35, or six months if you’re older than 35.

It’s not just fertility

When we talk about the difficulty of getting pregnant over the age of 35, it’s important to remember that it’s not just about conception rates.

The older you are, the higher your chances of miscarriage or stillbirth.

The risk of a baby with serious birth defects, which might lead you to consider an abortion, also rises over the age of 35. According to one study, 10% of pregnancies end in miscarriage for women in their early 20s, but that rises to 18% for women over 35, and 34% for women in their early 40s.

That means that you have a 40% risk of losing your baby when you’re 40, but only a 15% risk when you’re in your 20s. This is mainly because as you age, the quality of your eggs drops as well as the quantity. With a drop in egg quality comes a higher risk that a fertilized egg won’t divide correctly, leading to chromosomal defects.

Why does it get so much harder to conceive once you’re over 35?

The main reason why your fertility drops by around this age is because you don’t have very many eggs left. Women are born with around 1 million eggs, but by the time you reach puberty there are only about 300,000-400,000 remaining. This number gradually drops, and by the time you’re 35 there are only a few dozen that could be suitable for fertilization. You could begin to have menstrual cycles where no egg is released.

When you’re older, there’s also a greater chance that you’ve had some kind of surgery or infection that could have affected your fertility by leaving scars around the cervix or fallopian tubes. You’re also more likely to have developed conditions such as endometriosis or uterine fibroids, which make it much harder to become pregnant.

As you age, you also experience a natural decline in cervical mucus, which plays a key role in conception by helping sperm through the cervix and into the uterus and fallopian tubes so that it can fertilize the egg.

Once you’re over 35, every year can affect your chances of success in becoming a parent, so it’s important to seek medical assistance as soon as you see that you’re having difficulty conceiving. Whether you continue your path to building your family through IVF, donor eggs/sperm, or natural conception, we hope that your experience is as smooth as possible.

Male age matters, too

It’s not just the woman’s age that affects your chances of conceiving a baby naturally. The age of the man also plays a role.

Male fertility doesn’t decline as quickly as female fertility, but the time men are in their late 30s it has dropped noticeably. One study found that women aged 35-39 with a partner in the same age bracket have a conception rate of 29%, but if her partner is five or more years older, their conception rate is only 18%.

Multiple factors contribute to fertility

People will tell you to attempt conception before the “magic” age. As we’ve shown, there is no predetermined number where your fertility (or your partner’s) will drop. That said, the chance to conceive and carry a healthy baby to term drops as you age, as your partner ages, as you have less viable eggs available, as the chances of miscarriage and stillbirth increase. It’s best to attempt conception earlier, but there’s no magic formula - or age - to ensure success.