Getting pregnant at the age of 40 is probably more common than you may realise, though it is a fact that the body faces some unique challenges during pregnancy as a woman ages.

However, if you are trying to conceive at an older age, you need to be aware that even though fertility declines naturally as you age, it is possible to get pregnant after the age of 40.

If you are still having your periods, there is a chance you can get pregnant, although you have a much lower chance of conceiving naturally once you celebrate your 40th birthday than earlier in your reproductive years.

There is about five per cent chance during your menstrual cycle that you might get pregnant naturally once you are 40 years old. Compare this to a 25 per cent chance per cycle when you were in your 20s, when your fertility was at its peak.

There are many reasons for the decline in the success rate of pregnancy after 40. The rate of miscarriage is about 40 per cent after the age of 40. This can be due to many reasons, but the biggest reason is that there is a higher chance of genetic abnormality in each egg.

As a woman, your ovarian reserve also decreases over time, meaning you have fewer eggs left by the time you turn 40. The story around eggs is one that has been told several times. When you were born, your ovaries contain all the eggs that you would ever have – about a million in total. This number declines as you age because you typically lose about 30 immature eggs daily. And it’s not just you; this is what every woman of reproductive age experiences.

By the time you reach puberty, your ovaries would contain around 300,000 eggs; and by age 30, you are down to 100,000. At 40, you would have no more than 20,000 eggs left, and these are more than enough for your fertility needs.

Your ovarian reserve can be tested with a blood test called the Anti-Mullerian Hormone test. AMH is a hormone produced by the follicles in your ovaries where egg cells develop. This declines throughout your reproductive lifespan. The lower your AMH number, the fewer eggs remain in your ovarian reserve. But the AMH test result doesn’t tell anything about the quality of the remaining eggs.

The percentage of normal eggs that every woman has decreases as she ages. After age 40, the percentage of genetically abnormal eggs increases. This means that even if those eggs are fertilised, the pregnancy may not end in a live or genetically normal baby.

Clinically, at age 25, a woman has approximately 75 per cent normal eggs. By age 35, that number drops to around 45 per cent, and by 40 years, it’s around 20 to 30 per cent. This is one reason why most physicians recommend genetic testing for abnormal conditions in women pregnant after 40 years.

Besides naturally declining fertility, another challenge you can face as a woman that is over 40 is that you may have been diagnosed with other conditions which can cause pregnancy complications and/or more difficulties getting pregnant. You are at risk if you are obese, hypertensive, diabetic or have thyroid disorders, fibroids and endometriosis.

If you have other medical conditions, you should make sure your physician is aware that you are trying to conceive so that they can optimise your health appropriately to prepare for the pregnancy. A preconception counselling appointment with your regular gynaecologist can help pinpoint areas for improvement and give you personalised recommendations.

Remember that help is available if you haven’t got pregnant. Your fertility specialist can assist with fertility issues, so do not overlook a consultation with a specialist on the options available to you.

Abayomi Ajayi