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How age affects fertility

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

Helpful tools
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For women

The more advanced age a woman is, the more difficult it is to conceive.

Even after pregnancy, there is also a higher chance of miscarriage in women aged 37+.

  • Women are born with all the eggs they will ever have, unlike men whose bodies create new sperm indefinitely, although age does affect men’s fertility too.
  • Scientists believe that each woman is born with around 2 million eggs, but over time, the quantity and quality diminishes. In fact by puberty, about half is gone, as they deteriorate and be absorbed by the body.
  • By age 30, a woman will only have about 6% of the 2 million eggs she was born with.
  • By age 40, many women will face difficulty conceiving because fewer than 20% of the remaining eggs are considered ”genetically” normal.
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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. 

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.

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The Biology

  • When sex cells divide, they undergo a process called meiosis.
  • Telomeres are structures at the end of each chromosomes, similar to the glued tips at the end of shoelaces to prevent from fraying.
  • As cells age, telomeres progressively shortens. They act as the ‘aging clock’ in every cell to the point where the telomere is too short and cell division is no longer possible, the cell degenerates and dies.
  • As women grow older and when our telomeres shorten, cells tend to make more mistakes when they divide, leading to high chances of chromosomal abnormality.
  • These correlates with a lower implantation rate (i.e. pregnancy rate) and higher rate of miscarriage.
Segregation1
Segregation

As women age, the remaining eggs tend to make more ‘mistakes’ such as missing, damaged or extra chromosome, it leads to difficulty in implantation. This is also the reason behind higher rate of miscarriage in older women.

Women’s age has been shown to be one of the most important predictors in IVF

Anti-Mullerian Hormone (AMH)

Anti-Mullerian Hormone (AMH) is currently the gold standard for ovarian reserve testing. An AMH test is useful to understand if a woman will menopause earlier. More about AMH Test here
 

Anti-Mullerian Hormone (AMH) is the most reliable marker to determine ovarian reserve. It is also the starter test ordered by fertility specialists.

Knowing and tracking one’s AMH level can give a better understanding of reproductive health, to help you make a plan around your unique timeframe.

Whilst high AMH gives some assurance with regards to the number of eggs one has, it is however not an assurance of pregnancy. Even if it is low, it does not necessarily mean that you are infertile.

It helps to understand that your reproductive years may be shorter than you realized. This gets you to plan ahead about starting a family sooner or to consider egg freezing.

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

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Dr. Lim Lei Jun, Fertility Specialist
"Whilst high AMH gives some assurance with regards to the number of eggs one has, it is however not an assurance of pregnancy. Even if it is low, it does not necessarily mean that you are infertile." - Dr. Lim Lei Jun, Fertility Specialist.

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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