When Is the Best Day to Take a Hormone Test? A Complete Guide to Cycle Day 3 Testing-image

When Is the Best Day to Take a Hormone Test? A Complete Guide to Cycle Day 3 Testing

If you’ve ever been told to get bloods done on day 3 and wondered why that specific day matters, or felt frustrated trying to time a test around an unpredictable cycle, this guide is for you. We’re going to explain not just when to test, but why the timing matters at a biological level, what each hormone is actually measuring, and what to do when life doesn’t cooperate with your cycle. First: What does “day 3 of your cycle” mean? Day 1 of your cycle is the first day of your period, this means full menstrual flow, not spotting. If you see light spotting on Monday and Tuesday but don’t experience a proper flow until Wednesday, Wednesday is your day 1. Count forward from there: day 3 is the third day of your period (in this scenario that would be Friday). If your period is less than 3 days, day 3 is the third day after your period starts.  This matters because starting the count from spotting rather than full flow is one of the most common reasons people test at the wrong time. How does the menstrual cycle affect hormone levels? To understand why day 3 matters, it helps to have a basic picture of what’s happening in your body across the menstrual cycle. Your menstrual cycle is divided into two main phases separated by ovulation. The follicular phase always begins on day 1 of the menstrual cycle and ends with ovulation. In a 28-day cycle, the follicular phase extends from day 1 to approximately day 14. The luteal phase then follows ovulation and typically lasts 14 days, ending when your next period begins. The follicular phase is a period of rapid hormonal change, making it significant for hormone testing. When the previous menstrual cycle completes, levels of oestrogen and progesterone decrease. This triggers the release of follicle-stimulating hormone (FSH) into circulation.  Therefore, the days right around day 3 are when your body’s hormone system essentially resets and returns to its baseline. This is precisely why it’s the ideal time to take a snapshot of your reproductive hormones. Which hormones can be tested on day 3, and what does each one tell us? At Hertility, we test a broader panel than many providers. Here’s a detailed breakdown of each hormone in our Advanced At-Home Hormone and Fertility Test and why its timing matters. The Cycling Hormones These are tested on day 3 as mentioned earlier because they are at their ‘baseline’ around the first few days of your cycle. FSH (follicle-stimulating hormone) FSH is made by the pituitary gland in the brain and is the primary driver of egg development. FSH stimulates the production of oestradiol and eggs (oocytes) during the first half of the menstrual cycle.  Your FSH on day 3 might tell us whether the body is working as we would expect, or a little bit harder to induce follicular growth which may indicate reduced ovarian reserve, suggesting the egg supply could be beginning to decline.  Oestradiol (E2) Oestradiol is the primary form of oestrogen produced by the ovaries, and it plays a complex, interconnected role with FSH. Oestradiol serves as the brakes for the brain’s production of FSH. It travels from the ovaries to the brain and signals it to dial down FSH levels.  This is why FSH and oestradiol are always measured together. Not only their results, but their interpretation relative to each other is important for our clinicians to determine whether there is anything going on.  LH (luteinising hormone) LH is best known as the hormone that surges dramatically at mid-cycle to trigger ovulation. But measuring it at baseline on day 3 also tells us something important. If LH is too high on day 3, it may signal a condition like polycystic ovary syndrome (PCOS). An elevated LH:FSH ratio in the early follicular phase is one of the hormonal patterns clinicians look for when investigating PCOS and irregular ovulation. AMH (anti-Müllerian hormone) AMH is one of the most valuable markers for assessing ovarian reserve, and it works quite differently from the cycling hormones.  Historically, it has been thought that AMH doesn’t fluctuate dramatically across the cycle in the same way, so could be measured at any point during the menstrual cycle. However, research does suggest there may be some variation, which is why at Hertility, we standardise AMH testing to the days 2-5 window. This allows us to negate any potential fluctuation and ensure our results are consistent and comparable over time. AMH tells us about egg quantity (how many follicles are available) but it’s important to note it doesn’t directly measure egg quality. It should always be interpreted alongside your other results and your clinical history. Thyroid hormones (TSH and free T4) Thyroid hormones don’t fluctuate with the menstrual cycle, so strictly speaking they don’t need to be tested on day 3. We include them in the same panel because thyroid dysfunction, both overactive and underactive thyroid can significantly disrupt ovulation, cycle regularity, and fertility outcomes. Testing them alongside your reproductive hormones gives a more complete picture of your overall hormonal health in a single sample. Androgens (including testosterone) Androgens like testosterone are relatively stable across the menstrual cycle, making cycle timing less critical for these markers. That said, testing during the early follicular phase, when oestrogen is at its lowest means androgens aren’t being masked or influenced by rising oestrogen levels. For women investigating conditions such as PCOS, elevated androgens are an important part of the diagnostic picture. Prolactin Prolactin can technically be tested on any day. What does affect prolactin is the time of day and lifestyle factors. Prolactin naturally rises during sleep and can remain elevated for some hours after waking. Stress, physical activity, and even eating can temporarily raise levels. This is why Hertility asks you to take your sample first thing in the morning, before eating or exercise, to capture the most stable reading. The science behind day 3 testing: what does the research actually say? Day […]

Prolactin 101: Everything You Need to Know About Prolactin-image

Prolactin 101: Everything You Need to Know About Prolactin

Prolactin has several important functions in the body. But what exactly does prolactin do and how do we know if our levels have become imbalanced? In this article, we’ll dive into exactly what prolactin is, what its functions are in the body, discuss imbalances in its levels and the importance of testing prolactin levels for reproductive and overall health. Quick facts: What is prolactin? Prolactin is a hormone that encourages breast growth and milk production during and after pregnancy, as well as maintaining our metabolism, regulating our stress response, maintaining a functioning immune system and in the development of our reproductive organs.  Similarly to follicle-stimulating hormone (FSH) and luteinising hormone (LH) it is secreted by the anterior pituitary gland, located at the base of the brain. From there, it’s released into the bloodstream where it travels around the body to carry out its functions.  Prolactin interacts with FSH and LH, and other cycle hormones, in a complex negative feedback loop. After ovulation prolactin production increases to prepare the body for a potential pregnancy. Prolactin’s role in breastfeeding In pregnant women, prolactin stimulates milk production in the mammary glands of the breasts—allowing for the secretion of breast milk. After birth, there is a postnatal rise in prolactin, which gets things started—but this isn’t enough to maintain breast milk development. When a baby suckles, prolactin levels in the blood increase in response, which stimulates the production of more milk. Prolactin levels spike around 30 minutes after the start of the feed, so this positive feedback effect is important for ensuring there is enough milk for the next feed.  This can also be stimulated by breast pumping, if you choose not to, or are unable to breastfeed. Prolactin levels Just like all of our hormones, from time to time, our prolactin levels can get off balance. This can cause a whole range of different symptoms and effects throughout the body, including affecting our thyroid hormones, stress hormones, menstrual cycles and ovulation. What are normal prolactin levels? Reference ranges for what is a normal prolactin level will be specific to the lab that is testing your sample.  Higher prolactin levels are usually present in those assigned-female-at-birth than those assigned-male-at-birth. In general, prolactin levels are expected to be less than 25 μg/L in those assigned-female-at-birth, who are not pregnant or breastfeeding. High prolactin levels Too much prolactin can stop our brains from producing FSH and LH—two key hormones involved in regulating our menstrual cycles and bringing about ovulation.  If FSH and LH are affected, ovulation can stop leading to the loss of periods, which is called amenorrhoea. No ovulation means no chance of a pregnancy, and therefore big issues for our fertility. Disruption to our menstrual cycle can also cause knock-on effects on our oestrogen levels, causing oestrogen deficiency. Some of the most common symptoms of high prolactin levels to look out for are milky white discharge from the nipples when not breastfeeding (galactorrhea), disturbances to the menstrual cycle, visual disturbances, headaches and symptoms of oestrogen deficiency. High prolactin levels can be caused by a variety of reasons, including imbalances in our thyroid and stress hormones. Additionally, a growth or tumour present in our pituitary glands, called a prolactinoma, can also cause persistent or increasing prolactin levels. Symptoms of high prolactin levels can include: Note: If you are experiencing any form of nipple discharge when not breastfeeding, get this checked by a physician or GP as it can be a symptom of breast cancer. Symptoms of high prolactin levels after menopause Although high prolactin levels are not common in those postmenopausal, it can occur. Excess prolactin after menopause often causes hyperthyroidism, when the body doesn’t make enough thyroid hormone. Symptoms can include: How to lower prolactin levels If you’re wondering how to reduce prolactin levels, this is very much dependent on the cause of your excess prolactin levels.  Your doctor may prescribe you medications like bromocriptine or cabergoline to lower your prolactin secretion. Surgery may also be recommended as the best treatment option for you.  Persistently high prolactin that has been caused by chronic stress, over-exercising or poor sleep may be lowered by lifestyle modifications. Low prolactin levels On the flip side, low prolactin levels is called hypoprolactinemia. Sometimes there aren’t any obvious symptoms of low prolactin levels, other than not being able to produce or release much breast milk after giving birth. Breastfeeding can increase our prolactin levels naturally—as the more we stimulate the nipples, more prolactin is produced.  Most people with low prolactin levels don’t have any specific medical issues, although there is preliminary evidence that suggests they might have reduced immune response to some infections and it could indicate that the pituitary gland isn’t functioning properly. Why should we test our prolactin levels? Like all of our reproductive hormones, it’s good to check in with prolactin regularly, especially if we’re trying to conceive or having any problems with our menstrual cycles or experiencing hormonal symptoms.  Testing our prolactin levels with a prolactin blood test can help us to determine if there are any hormonal issues affecting our fertility or menstrual cycle, or investigate any symptoms of prolactinoma. With a Hertility advanced hormone and fertility test, we can test your prolactin levels alongside your Anti müllerian hormone (AMH), thyroid hormones and cycling hormones (FSH, LH and oestrogen) to help you gain a full insight into your hormonal health and fertility. If you’ve already done a test and received an abnormal prolactin result, you can book an appointment with one of our Private Gynaecologists specialising in hormone and fertility concerns to discuss your results and get a personalised care plan. Appointments are available daily, with no GP referral required. Prolactin FAQs Can I get an FSH, LH, Prolactin test all in one? Luckily, you’re in exactly the right place. With our Hormone and Fertility test we will test you for up to 10 reproductive hormones, including your FSH, LH, prolactin and more.  Do prolactin levels change with age? Unlike hormones like Anti Müllerian […]