Fertility Calculator

Isn’t it ironic that we spend most of our younger years trying desperately not to fall pregnant, paranoid when our period is a day late that things are going to be forced to get waaaay too serious with that new guy, and thinking that every ‘forgotten’ Pill, or condom hole is going to result in a baby? 

But then…fast forward a few years… you’re ready for a baby…in fact, your brain has been taken over by your need for a baby. You learn that doing ‘the deed’ can only result in a pregnancy on about 3 days out of 28…and even then, it doesn’t always happen straight away. You’ve never felt so out of control of your life…How are you meant to plan the year ahead if you don’t even know when you’ll get pregnant? What happens if you can’t even get pregnant?!

Your partner is so relaxed… “It’ll happen when it happens” he says… “There’s no rush”.

But to you it doesn’t feel like a ‘no rush’ situation.

What happens if you run out of eggs? What happens if you end up needing IVF when you can barely afford to pay a deposit on a 2 bedroom apartment? What happens if he breaks up with you because you’ve become so baby-obsessed and you have to start the whole ‘finding the one’ process again?!

Wouldn’t it be great if there were ways to help put your mind at ease and give you an idea of where you are at with your fertility?

Turns out, there are! In fact, there are a range of fertility tests that can help estimate your egg numbers, how much time you may have up your sleeve, and even predict how well you may tolerate IVF. 

Let’s look at the different fertility testing options that may be available to you.

AMH Testing

The anti-Müllerian hormone (AMH) is secreted by the cells of the follicle (egg sac) in females, and testing has become an important step in the fertility journey. AMH testing provides you with an indication of your egg count, or your ovarian reserve.¹

AMH testing does have some limitations. Whilst it’s a great indicator of ovarian reserve, and therefore an indirect marker of expected fertile years left, AMH is incapable of assessing the quality of the remaining eggs, and therefore can’t reliably predict the likelihood of pregnancy.¹

Factors Influencing AMH Levels

AMH levels can also be altered by medication, illness and/or some medical conditions.²

• The contraceptive pill
• Polycystic Ovarian Syndrome (PCOS)
• Chronic vitamin D deficiency
• Chronic stress
• With a history of ovarian surgery or chemotherapy
• BRCA mutations

AMH testing can also be used to predict a woman’s reaction to various elements of Assisted Reproductive Technology, such as ovarian stimulation, and can therefore help guide your fertility specialists towards the most appropriate protocol for you.¹

Follicle-Stimulating Hormone (FSH) & Luteinising Hormone Tests

Combined, these hormones are known as gonadotropins, and, in terms of fertility, they are inextricably linked.

FSH and Luteinising Hormones are both produced by the pituitary gland, just beneath the brain, and the tests are often run simultaneously.³ FSH helps control women’s menstrual cycles, and triggers the growth of eggs in her ovaries. There are fluctuations in FSH levels throughout the menstrual cycle, with the highest levels being measured just before ovulation.³

These tests are often run to examine ovarian function, find out reasons for irregular or missing periods, or determine the onset of peri/menopause.³  

For women:

Prolactin (PRL)

PRL is generally elevated in pregnancy, but if high levels are found without pregnancy, this can indicate a small tumour in the pituitary gland, or the use of certain medications, as well as irregular, or no, periods.⁴

Thyrotrophin (TSH)

Altered levels of TSH can indicate an underachieve thyroid, which can be linked with irregular periods.⁴

Androgens

Elevated androgen levels can be an indication of PCOS or ovulatory problems and is therefore an important hormone to test for if fertility is in question.⁴

Sex Hormone Binding Globulin

Testing the levels of SHBG in your blood can show how much free testosterone you have…i.e. testosterone that is unattached to protein and available for your body to use. An SHBG test may be ordered if you are female and you have symptoms of high testosterone, such as excess facial hair, a deepened voice, irregular/no period, acne, weight gain, or fertility problems.⁵

Overall Fertility Calculation

In addition to these tests, your age and level of sexual activity, which are unsurprisingly also intertwined, are also good indications of your chances of falling pregnant.

As an independent marker, age decreases the quality of your eggs, increases your risk of miscarriage, and increases the risk of fertility-and pregnancy-related disorders.⁶ From about the age of 32, fertility starts to slowly decrease, and after the age of 37, this decline becomes more rapid.⁶

Whilst this topic can feel ‘big’, opening the discussion up is so important, and is too often considered a bit taboo or uncomfortable. Having knowledge about your fertility should feel empowering, and gaining the tools to calculate where you’re at with your own fertility can be a game-changer.

References

1. Dewailly, Didier, and Joop Laven. "AMH as the primary marker for fertility." European journal of endocrinology 181, no. 6 (2019): D45-D51.

2. Oh, So Ra, Sun Yi Choe, and Yeon Jean Cho. "Clinical application of serum anti-Müllerian hormone in women." Clinical and Experimental Reproductive Medicine 46, no. 2 (2019): 50.

3. MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated Dec 17, 2020]. Follicle-Stimulating Hormone (FSH) Levels Test; [updated Dec 17, 2020; cited 2023 Apr 14]; [about 2 p.]. Available from: https://medlineplus.gov/lab-tests/follicle-stimulating-hormone-fsh-levels-test/

4. The Royal Women’s Hospital [Internet]. Fertility Testing: Blood Tests; [cited 14 Apr, 2023]; [about 1 p]. Available from: https://www.thewomens.org.au/health-information/fertility-information/fertility-problems/fertility-testing

5. MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated Dec 17, 2020]. SHBG Blood Test; [updated Dec 14, 2022; cited 2023 Apr 14]; [about 3 p.]. Available from: https://medlineplus.gov/lab-tests/shbg-blood-test/

6. No, Committee Opinion. "Female age-related fertility decline." Fertility and Sterility 101, no. 3 (2014): 633-634.