The biological clock, female fertility decline

In this blog I am going to introduce you to the main topics covered in Chapter 2 of my book, Your Fertile Years; The biological clock, female fertility decline. If you want to have children in the future, this is one of the most important pieces of information you need to know. A video summarising Chapter 2 can be found on Joyce’s YouTube channel.

As an educator of women’s health, I find it very frustrating that many women resort to Google, forums, social media or the media in general to learn about their fertility. But where else can they learn? Through these channels it is difficult to find the right information because there are many conflicting messages, especially in regard to female fertility decline.

Let’s start by looking at the major gender inequality.

An average male ejaculation produces around 100 million sperm, a number high enough to make all the women in the United Kingdom pregnant. Sperm form from puberty until death, with new sperm continuously being produced. It is quite easy to think of famous men who fathered children in their 50s, 60s and even 70s, including: Michael Douglas; Bruce Willis; Jeff Goldblum; and Rod Stewart. One thing they all have in common is a much younger partner.

Unlike men, women do not stay fertile their entire lives. It becomes more difficult to conceive as they reach their late 30s, and in their 40s, becoming pregnant is incredibly difficult. By the age of 43-44, most women will no longer be able to become pregnant, either naturally or with Assisted Reproductive Technologies (ART) such as In Vitro Fertilisation (IVF).  How many older celebrity mothers can you think of? It is hard to think of any. Bridget Neilson was 54; Janet Jackson was 50; and Rachel Weisz was 48. It is very possible that they had expensive fertility treatment or used a donor egg.

Why are women less fertile as they age?  

Female fertility decline is caused by the quality and quantity of eggs decreasing as a woman matures. When women reach the menopause, they will no longer have any viable eggs left and will be unable to become pregnant with their own genetic child. Also, the quality of eggs decreases with age, making the egg less likely to result in a pregnancy.  But wombs can stay ‘fertile’ and so if an egg from a young egg donor is used, women can still carry and deliver a child at almost any age.

Women are born with all the eggs they are going to have. At birth women have about 1-2 million potential eggs. But by puberty, many have died so  we only have around 400,000 remaining eggs. At each menstrual cycle a few eggs will mature, although usually only one is ovulated and up to 1000 die, even if we are on hormonal contraception and are not ovulating. In our whole reproductive life, women only ovulate about 400-500 eggs and some of these will not be viable.

IVF treatment

Surely IVF can help women of older ages have a successful pregnancy?  The media have often presented IVF as a miracle solution that can help women become pregnant at any age. However, IVF cannot make up for the loss of fertility as women become older because the quantity and quality of eggs declines and we cannot change this. Success rates from IVF treatment fall with age exactly as they do with natural conception.

In the UK, IVF is governed by the Human Fertilisation and Embryology Authority. In the latest HFEA data from 2018, the chance of a live birth from IVF under the age of 35 was 31 per cent, but this decreases every few years: ages 35–37 it is 25 per cent; 38–39 is 19 per cent; 40–42 is 11 per cent; 43–44 is under 5 per cent; and this drops to under 4 per cent for women the age of 44 and older (see graph below). The HFEA do not show data over 44 because by the age of 45–46, the chance of a baby by IVF with one’s own eggs is zero.

In America, the IVF data is grouped similar to the HFEA data. The US data for 2017 shows that for women under the age of 35 there is a live birth rate per egg collection for the first transfer of 41 per cent; then 35–37 it was 32 per cent; 38–40 22 per cent; 41–42 was 11 per cent and over 42 years was 4 per cent. They do not go above this age.

Global increase in the age women are having children

We have a global problem because women are delaying the birth of their first child. Almost all countries have seen an increase in the average age women have their first child and in many countries this is now over 30 years of age including: Ireland; Italy; Japan; South Korea; Luxemburg; Portugal; Singapore; Spain; and Switzerland.

In the United Kingdom in 2016, 54% of all live births in England and Wales were to mothers aged 30 and over. We have seen a decrease in the number of teenage pregnancies and an increase in older mother pregnancies.

Global fertility rates

When I was a child, we said that families had an average of 2.4 children. This is called the fertility rate; the average number of children women of a certain population have. Overall, in the European Union, the fertility rate has dropped to 1.6 and in some countries, such as Greece and Poland, it is as low as 1.3. China reversed its one child policy partly for economic reasons because there were not enough young people to keep the country going. If the fertility rate continues to go down globally, we could have a worldwide economic crisis.

What is your ideal age you would like to have children? Do you think you will be affected by female fertility decline?

Read More

Order a signed copy of Your Fertile Years using the Paypal link on www.joyceharper.com including your full address. The cost is £10 plus postage and packing. Contact yourfertileyears@gmail.com if you would like Joyce to give a talk to any group or at any event.

Blogs
Chapter 1: Knowing Your Body; Understanding Your Menstrual Cycle And Fertile Window
Chapter 2: The biological clock, female fertility decline
Chapter 3: Optimising your reproductive health
Chapter 4: Everything you should know about sex
Chapter 5: If you do not want to become pregnant, how do you prevent it?
Chapter 6: How Can Sexually Transmitted Infections Affect Fertility?
Chapter 7: What you should know about pregnancy and childbirth
Chapter 8: Is egg freezing the answer to female fertility decline?
Chapter 9: What causes infertility and how we test for it
Chapter 10: Debunking the myths of fertility treatment
Chapter 11: The menopause is not far away
Chapter 12: What does the future hold for reproduction?

And videos to accompany the blogs on my YouTube Channel
Why I wrote Your Fertile Years
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Chapter 12