When should women start thinking about their future fertility?

Did you know that women are born with their entire lifetime supply of eggs? At birth, a girl's ovaries contain approximately two million eggs; this decreases monthly, and by puberty, only 25% of her egg pool remains [1].

In our 20s, thinking about our fertility is probably not uppermost in our minds – we take it for granted that by the time we want children, we'll be able to have them. But as we approach our early to mid-30s and are wrapped up in careers and just getting on with life, many women start to have nagging doubts about whether they could be leaving it too late to start a family.

Let's look at why it's so important to plan and the things which can help you to make the right choices.

Can you measure future fertility?

Female fertility is predominantly measured by the quantity and quality of a woman's eggs, and as mentioned, this supply declines with age. Each month one dominant egg is stimulated by hormones; it matures and then travels down to the womb. This egg has 48 hours to be fertilised; otherwise, it breaks down, and the monthly cycle begins again.

When a woman chooses to begin trying to conceive is her choice, but unfortunately, nature also has a say in this decision, with fertility declining steadily after the age of 30. Research shows that in recent years, more women are waiting to start a family [2]. This could be for a multitude of reasons, such as pursuing a career or waiting to find the right partner, but regardless it is necessary to consider all the implications.

The upside of delaying pregnancy is that you have more life experience and will probably be in a better financial position; however, it also has risks. Although we all know many women who conceive in their late 30s and even their early 40s, delaying pregnancy into their late 30s can leave some women disappointed. There is no 'correct age' to have a baby, and unfortunately, not all women have a straightforward path to motherhood. It's important to think about when you want to start a family and prepare for all the possible outcomes.

Is there a test for female fertility?

Unfortunately, there is no single test that will predict your fertility, and even if there were, there are so many other factors that may affect a couple's ability to conceive a child. However, a test like our day three fertility test can be a helpful first test in an investigation into female infertility. Ideally, you should take our test three days after the start of your period, but it can also be taken on days two, four, or five of your menstrual cycle. This test aims to check that hormone levels can support the maturation and release of a healthy egg from the ovary. measures three separate hormones, which together can provide some insights into whether you are heading towards menopause, and whether your egg supply (ovarian reserve) is normal for your age.

There are four hormones that may be tested to give an overall view of your future fertility. These include follicle-stimulating hormone, luteinising hormone, oestradiol, and anti-Mullerian hormone. 

Four hormones for female fertility 

1. Follicle-stimulating hormone (FSH)

Follicle-stimulating Hormone (FSH) is made in the pituitary gland, which controls the menstrual cycle and egg production. Once stimulated, eggs produce the hormone oestradiol. But as the number of viable eggs declines over a woman’s lifetime, the amount of oestradiol produced by them also falls, which signals to the pituitary gland to make more FSH to try to stimulate egg production. Therefore, high levels of FSH may suggest that your body is struggling to make eggs and is trying to compensate. High FSH is typically seen in menopausal women, but it is worth noting that FSH levels can vary extensively during perimenopause (the years preceding menopause), being normal one month, and high the next as the menopause nears.

2. Luteinising hormone (LH)

Luteinising hormone (LH) is produced by the pituitary gland and is important for both male and female fertility. In women it governs the menstrual cycle, peaking before ovulation, and is needed for the final maturation and release of the egg from a follicle (a fluid-filled sac containing the egg). In men, it stimulates the production of testosterone. 

3. Oestradiol

Oestradiol is a steroid hormone that is produced by a developing egg in the ovaries. It is responsible for preparing the uterus for implantation. Oestradiol levels decline as you age so that by the time you reach menopause, your oestradiol levels will be a fraction of their peak levels. Low oestradiol, together with elevated FSH, can indicate that you may be becoming menopausal. During perimenopause oestradiol, like FSH, can fluctuate hugely. A single low oestradiol or high FSH result may not be significant, and also may not mean that you can't conceive. However, it may be a sign that your body is starting to transition into menopause.

4. Anti-Mullerian hormone (AMH)

AMH is a hormone created by follicles within your ovary, which helps to predict egg yield. The more eggs/follicles you have, the higher the anti-Mullerian hormone level is likely to be [3]. Measuring AMH can help diagnose premature ovarian failure and is used by fertility clinics to assess the likelihood of successful egg retrieval. High AMH levels can also be caused by polycystic ovaries, and there is ongoing research into how this test could help in the diagnosis of polycystic ovary syndrome. For women interested in their future fertility, it can help guide them in family planning. Anti-mullerian hormone is not a precise measure of how many viable eggs a woman has and should only ever be used as a guide. We suggest that a low AMH result should be followed up with an antral follicle count scan where a doctor counts the number of activated follicles in the ovaries.

Our Day 3 Fertility Blood Test can give you an idea of your ovarian reserve. It may be helpful if you are currently trying or thinking about starting a family and would like to check your reproductive hormones. If you'd like to find out more about hormonal changes through pregnancy, read our guide to pregnancy hormones. 

References

1. Rogelcancercenter, (2020). Normal Ovarian Function. [online] Available at: https://www.rogelcancercenter.org/fertility-preservation/for-female-patients/normal-ovarian-function [Accessed 04/02/20].
2. Baptiste, N. (2014). While Waiting for a Life Partner: Wisdom Keys for Single Christian Women. Indiana: AuthorHouse, Pg 92.
3. Waggoner, M. (2017). The Zero Trimester: Pre-Pregnancy Care and the Politics of Reproductive Risk. California: University of California Press, Pg 134.
4. American Society for Reproductive Medicine, (2012). Age and Fertility. [online] Available at: https://www.reproductivefacts.org/globalassets/rf/news-and- publications/bookletsfact-sheets/english-fact-sheets-and-info-booklets/Age_and_Fertility.pdf [Accessed 04/02/20].