So you are thinking about doing a fertility test or perhaps your doctor has ordered these for you. Whether you go to a fertility clinic or do an at-home test like the one at Parla, you will generally be advised to test on Day 3 of your cycle – hence the name Day 3 Testing! It’s a widely used blood test that checks for different hormone levels on day 3 of your menstrual cycle (“cycle day 3” or “CD3” testing. Day 3 testing is useful in guiding fertility treatments but also in diagnosing conditions like polycystic ovary disease or ovarian cysts.
Your Menstrual Cycle
Before we tell you more about this type of testing, let’s do a quick recap of the menstrual cycle to be able to understand the role of hormones and why day 3 is so important.
Your Period
Our brain and ovaries are constantly communicating and signalling to each other which leads to the secretion of hormones (chemical messengers) and changes in our bodies. Your menstrual cycle starts on the first day of a period. During that time, the levels of our hormones are low.
Follicular Phase
During the first part of the cycle, eggs are being prepared to be released from the ovary and the lining of the uterus builds up (for potential implantation and pregnancy). In each ovary, there are multiple follicles (fluid filled sacs containing eggs) that grow under the influence of a hormone called FSH, however, only one of them will become dominant and will be released during ovulation. While the ovaries are working on developing the egg-containing follicles, the uterus is rebuilding the lining that was just shed in response to a hormone called oestrogen.
Ovulation
The crucial event for fertility – the release of the egg from the ovary. Estrogen peaks just before ovulation which gives a signal to the brain to release a hormone called LH. Surge in LH causes ovulation. This usually happens 14 days before your next period.
Luteal Phase
The second part of the cycle prepares the uterus and body to accept a fertilised egg (prepares the body for a potential pregnancy). At this time, progesterone levels are high. If fertilisation does not occur, the lining of the uterus is prepared for breakdown and shedding ( aka your period!)
Source: https://iapmd.org/hormones-and-pmdd
Which hormones do you test on Day 3 of your cycle?
The three hormones that the doctors are checking for in this test are:
- Follicle Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
- Estradiol (E2)
Another hormone, often checked alongside the Day 3 test is the Anti-Mullerian Hormone (AMH) but this one can be checked at any point in your cycle (as it’s fairly steady.). AMH is produced by cells of growing follicles and indicates the quantity of developing eggs in your ovaries. Sometimes, doctors may also check other hormones which may impact your fertility, like the thyroid hormones or prolactin.
Quick insights into Day 3 hormones:
- FSH – this hormone, as the name suggests, is responsible for promoting the growth of follicles. It’s typically low at the beginning of the cycle. As FSH levels rise, the follicles grow and eggs begin to mature (the number of growing follicles depends on your age). When there’s not enough of them, the hormone rises above expected as it tries to stimulate more follicles to grow. High levels can thus indicate poor ovarian reserve.
- LH – stimulates ovaries to produce other important hormones: oestrogen and progesterone. The surge of LH leads to ovulation (the release of a mature egg). Higher than normal levels of LH may suggest ovarian failure, a pituitary disorder, or polycystic ovarian disease. Low levels of LH could indicate malnutrition, anorexia, stress, or, again, a pituitary disorder.
- E2 – type of oestrogen which prompts maturation of the follicles, release of the egg, and thickens the uterine lining for the egg to have an ideal environment in which to implant. E2 levels should be low around day 3.
Learn more about the following fertility hormones to help you better understand your ovarian reserve, ovulation and thyroid health:
- Anti mullerian hormone (AMH)
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Prolactin (P)
- Thyroxine (T4)
- Thyroid stimulating hormone (TSH)
So, what do we have to test on Day 3 of your cycle?
These tests aim to quantify the amount of follicles in your ovaries which contain eggs and have the potential to become fertilised. This is often referred to as “ovarian reserve”. As fertility hormones fluctuate throughout the cycle but are relatively “at baseline” at the beginning, it’s really important to get the day of the test right. Moreover, at the beginning of the cycle, the eggs are growing in their follicles (individual sacs) so it’s the best time to try to measure them!
How can I pinpoint Day 3 of my cycle?
Day 3 of your cycle is essentially the 3rd day of your period. Full flow (not spotting) by 5:00 p.m. is considered day 1 of your cycle (source).
What happens if I test on 2 or 4?
Ideally the test is taken on the 3rd day of your period, but it can also be taken on day 2, 4 or even 5 of the menstrual cycle (source) as long as you are still experiencing period flow. Beyond that time, the test may not be accurate.
Why proactive hormone testing is a good idea
According to experts, even a small imbalance in your hormone levels can have a significant impact on your health, affecting not only your fertility but also your mood, energy levels and libido. Hormones are essential for body functioning as they instruct your body in everything it does – regulating appetite, growth, mood and reproduction. Hormone disorders are common and are often treated with hormone replacement therapy or lifestyle changes.
If you are thinking of doing testing to check your fertility, remember that the results may fluctuate between cycles. It’s also good to keep in mind, when undergoing such tests, that there are a number of reasons that may be contributing to subfertility and that a single test cannot give a completely accurate picture of your fertility status. It’s essential to speak to your doctor about your medical history and discuss other potential causes and investigations.
