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How age affects fertility

As everyone knows, you can’t escape the subject of age when it comes to understanding female fertility

Helpful tools
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For women

As everyone knows, you can’t escape the subject of age when it comes to understanding female fertility

The chance of pregnancy falls as a woman gets older, and the risk of miscarriage and abnormalities increases, even for people with no fertility problems. If you are having trouble becoming pregnant, the sooner you seek help, the better your chance of having a baby.

Percentage chance of birth per month using IVF v naturally
Percentage chance of birth per month using IVF v naturally
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Anti-Mullerian Hormone (AMH) testing

For some women, the effect of age kicks in early:

  • About 10% of women experience menopause 5 years earlier than average – around the age of 45 instead of 50. Their fertility will fall 5 years earlier than average.
  • About 1% of women go through menopause 10 years earlier than average, around the age of 35. Their fertility will fall 10 years earlier than average.

An AMH test is useful to understand if a woman will menopause earlier.

Ovarian Reserve is a term used to determine the number of eggs left in a woman’s ovaries.

The Anti-Mullerian Hormone (AMH) test is the best test currently available to estimate ovarian reserve, and may indicate the possibility of early fertility loss. However, it cannot show who is more fertile than average, nor does it predict ovarian reserve in women with Polycystic Ovaries (PCOS).

The Anti-Mullerian Hormone (AMH) test is the best test currently available to estimate ovarian reserve.

Your GP can request an AMH test, however we recommend an appointment with a fertility specialist to analyse the results, and to explain what they mean for you.

  • It is a single blood test that can be done at any time during the menstrual cycle.
  • It can help predict how many eggs you are likely to obtain in an IVF cycle.
  • It may also identify women who may undergo early menopause, and therefore who may lose their fertility earlier than average.
  • Your doctor or nurse will give you a separate blood form for the test and tell you where you can have your test done. The result is usually available a week or so after the blood has been taken. Your doctor will tell you the result in person, by telephone or by sending you a letter.
  • The interpretation of the AMH result will depend on your medical history, your family’s fertility history, lifestyle and other investigations into your fertility.
  • In some areas of New Zealand the AMH test is not publicly-funded. The cost is typically $85 to $110 depending on the lab.

Interpreting AMH

Like most fertility tests, an AMH test does not give a 'black and white' answer. We plot the AMH result on a graph, (see below), that shows the 10th, 25th, 50th and 75th centiles for AMH for women attending a fertility clinic. This lets you compare your results with women of a similar age and helps predict how your AMH level may change over the years. We have shaded areas of the graph green, orange and red to represent the average impact of your AMH level.

AMH centile graph

We’re here for you – whatever your age and stage of life

If you want to find out more about AMH testing, or to discuss your fertility options, we encourage you to book an appointment with us.

There are a variety of options available to women experiencing age-related fertility difficulties – we’ll guide and advise you as you search for what suits you best.

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For men

While there’s no male equivalent to menopause, and the age of the mother is more important where fertility is concerned, the number of sperm made each day, and their quality, do fall with a man’s age.

Pregnancies from older men show higher incidences of some types of abnormalities among children – such as schizophrenia and autism. The total risk of a child having a serious birth defect, (from the biological father, the mother, or newly arising in the child), increases from an average of 20 per 1000 children for men aged 20; to 26 per 1000 children for men aged 50.

A man’s age does not seem to affect the chance of success in fertility treatments such as IVF – at least up to the age of 50.

When to seek help

Knowing when to seek help can be confusing

Should you keep trying for a bit longer, or do you need to book an appointment to talk it through? Talk to one of our experienced fertility nurses in a free, no obligation 15 minute telephone chat. Book now. 

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FAQs

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Book a free 15 minute phone consultation with one of our expert fertility nurses.

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The Biological Clock

This tool indicates:

  • Natural conception per month if you have no fertility issues
  • IVF success rate at the same age
  • When to seek help after months of unsuccessful attempts

If you are concerned at any stage – we recommend booking a doctor appointment or a free nurse consultation. The sooner you make a plan the better your chances in the long term.

When to seek advice early

  • If you have polycystic ovaries, endometriosis, or have been through a cancer diagnosis; we recommend you get in touch quickly so we can talk you through all your options and give you the greatest possible chance of success.
  • If you’re a single woman considering motherhood in the future; it’s best to approach us early and consider egg freezing as this can be an option for you while you have a higher ovarian reserve and healthier eggs.
Set your age and the months you’ve been trying to conceive
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Your chance of having a baby per month for fertile couples
Your chance of having a baby per IVF cycle (if experiencing infertility)

Body Mass Index calculator

Being overweight or underweight can reduce fertility, so it is important to keep your body weight within the normal healthy range.

Body Mass Index (BMI) is an indication of your body weight and can be calculated by dividing weight by height. You should aim for a BMI of between 20 and 25, as this will optimise your chances of conception.

Woman’s BMI below 19

Even in these modern times, nature knows best. If a woman's BMI falls below 19, the body senses famine and ovulation is switched off to prevent the risk of having a baby with malnutrition. Excessive exercise can reduce body fat and increase muscle mass to a point where periods cease for the same reason. Risk of miscarriage is also increased in women with a low BMI.

Being underweight

If a woman's BMI falls below 19, the body senses famine and ovulation is switched off to prevent the risk of having a baby with malnutrition. Excessive exercise can reduce body fat and increase muscle mass to a point where periods cease for the same reason. Risk of miscarriage is also increased in women with a low BMI.

BMI’s greater than 30

This can reduce fertility by 50%. Pregnancy for women with a 30+ BMI is often associated with problems such as maternal diabetes, high blood pressure, big babies and increased risk of caesarean section.

Add your height and weight to calculate your BMI