Tag: menstrual cycle hormones

Oestrogen is a group of hormones that controls your menstrual cycle and supports your fertility, bones, heart, skin, mood and vaginal health. The main type before menopause is oestradiol. Your oestrogen levels rise and fall across your cycle and gradually fall with age, and levels that are too high or too low can cause symptoms. You might have come across oestrogen because your periods have changed, you’re trying to conceive, or you’ve noticed symptoms that could be hormonal. This guide explains what oestrogen does, how it changes through your cycle and life, the signs of high and low oestrogen, and how to get your levels tested. Quick facts: Not sure whether your oestrogen is behind your symptoms? Hertility’s Advanced Hormone and Fertility Test checks your oestradiol alongside other key hormones from home, timed to your cycle. You’ll get a doctor-written report explaining what your results mean for you. What is oestrogen? Oestrogen is a reproductive hormone that everyone makes, whatever their sex. Levels are much higher in women. It’s often called the “female” sex hormone because it drives the development of the female reproductive system and controls the menstrual cycle. Before menopause, most oestrogen is made in your ovaries by follicles, the small sacs that contain your developing eggs. Its production depends on other hormones: Smaller amounts of oestrogen are also made in fat tissue. What are the different types of oestrogen? Your body naturally makes three main types of oestrogen, plus a fourth specialised type found during pregnancy: Weak forms of oestrogens can attach to oestrogen receptors, but their effect on the body is less compared to more active oestrogens.  What does oestrogen do? Oestrogen wears many hats, it helps to regulate our menstrual cycles, triggers the development of secondary sex characteristics like breasts and pubic hair and helps to maintain things like our skin’s moisture, our mood and even our bone and heart health. Let’s take a look at these in more detail: How does oestrogen change during your menstrual cycle? Like all of our menstrual cycle hormones, our oestrogen levels during the menstrual cycle fluctuate.  1. At the start of your period, oestrogen is low. 2. In the first half of your cycle (the follicular phase), eggs mature inside follicles in your ovaries. As the follicles grow, they release more oestrogen, so levels rise steadily. 3. Just before ovulation, oestrogen peaks. This triggers a surge of LH, which causes a follicle to release a mature egg.  During this phase of your cycle i.e. from the start of your period to ovulation, oestrogen levels are high. You may notice your skin is feeling clearer and you have increasing energy levels and improved mood. Your cervical fluid also changes throughout the follicular phase, during the early to mid follicular it is dry or sticky, around the mid to late follicular phase it can become thicker, sticky or creamy and as you move towards ovulation, it becomes wet and slippery, like egg white. Additionally, some people notice an increase in their libido around ovulation. 4. In the second half of your cycle (the luteal phase). After the egg is released, the follicle’s walls form a new structure called the corpus luteum. The main function of the corpus luteum is to produce high levels of progesterone and some oestrogen. Progesterone rises to prepare your womb lining for a possible pregnancy. 5. If the egg isn’t fertilised, oestrogen and progesterone fall back to baseline, and this triggers your period. When oestrogen levels are lower before your period, you may start noticing Premenstrual symptoms (PMS). Why this matters for getting pregnant. Oestrogen helps trigger ovulation, so low or disrupted oestrogen can affect whether you ovulate. If you don’t ovulate, you can’t get pregnant. That’s why checking your hormones is useful if you’re trying to conceive. Read more about ovulation. What affects oestrogen levels? As well as fluctuating naturally month to month, lots of other lifestyle, genetic and medical conditions can affect our oestrogen levels, including: How does oestrogen affect your fertility? Oestrogen is involved in almost every step of getting pregnant. It triggers ovulation. As follicles grow in the first half of your cycle, they release more and more oestrogen. When levels peak, they trigger the surge of LH that releases an egg. It helps sperm reach the egg. Rising oestrogen changes your cervical mucus, making it clear, slippery and stretchy around ovulation. This type of mucus helps sperm swim through your cervix towards the egg. It prepares your womb. Oestrogen thickens your womb lining so that a fertilised egg has somewhere to implant. Progesterone then takes over after ovulation to keep the lining ready. If your oestrogen is low, you may not ovulate regularly, and your womb lining may stay thin. If your oestrogen is high compared with progesterone, it’s often a sign that you’re not ovulating every cycle. Either way, it can make it harder to conceive. That’s why oestradiol is one of the hormones usually checked when you’re trying to get pregnant. It’s also closely monitored during IVF and egg freezing, to track how your follicles are growing. If you’re trying to conceive and your cycles are irregular, Hertility’s Advanced Hormone and Fertility Test can help you understand what’s going on. Does oestrogen decline with age? Yes. As you get older, your ovaries contain fewer eggs and follicles, so they gradually make less oestradiol. During perimenopause, the years leading up to menopause, oestrogen doesn’t fall steadily. It goes up and down unpredictably, which can cause irregular periods, hot flushes and mood changes. Read our guide to what perimenopause is. After menopause, once you’ve gone 12 months without a period, oestradiol falls to low levels and oestrone becomes the main type. Lower oestrogen causes many common menopause symptoms, such as hot flushes, vaginal dryness, dry skin and mood changes. It also raises your long-term risk of osteoporosis and heart disease. Hormone replacement therapy (HRT) can relieve symptoms of low oestrogen for many people during perimenopause and after menopause. Find out more about […]

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 […]

Your menstrual cycle is the full sequence of hormonal and physical changes your body runs from the first day of one period to the first day of the next, not just the days you bleed. Your period is simply the part you can see. Getting to know it is one of the most useful things you can do for your health: it helps you make sense of your periods, spot your own patterns, and notice when something’s changed. And yet most of us were taught remarkably little. Hertility’s own peer-reviewed study of 383,085 UK women found that more than one in five didn’t know their cycle length, rising to one in three of those under 25. We really think that needs to change. Here’s exactly what happens between one period and the next: the phases, the hormones behind them, when ovulation happens, and what counts as normal. Quick facts: What is the menstrual cycle? First things first: your period and your menstrual cycle aren’t the same thing. The menstrual cycle is the series of hormonal and physical changes that happen from the first day of one period to the first day of the next.  So, if your period starts on 1 June and your next one starts on 29 June, you had a 28-day menstrual cycle. The first day you have a full bleed is day 1, spotting doesn’t count. Then you count each day until your next period begins. Underneath, two processes run in tandem. The ovarian cycle is what’s happening in your ovaries  – follicles develop, an egg may be released at ovulation, and the ovary then prepares for a possible pregnancy. The uterine cycle is what’s happening to your endometrium (your womb lining) – it sheds during your periodand grows back in preparation for an embryo to implant.  Both are carefully regulated by four cycling hormones – oestrogen, progesterone, luteinising hormone (LH) and follicle-stimulating hormone (FSH) and, as you’ll see, they map neatly onto each other. It sounds complex, but it’s far easier to follow phase by phase. How long is a normal menstrual cycle length? Thinking that every menstrual cycle is 28 days can be misleading for many women. For adults, a cycle of roughly 21-35 days is within the expected range, so 28 days can be perfectly normal, but so can 24, or 31. In fact, a study examining over 600,000 cycles found that only 13% of cycles in the study group were 28-days long – 29.3 days was the average.  Rather than expecting your to body fit a textbook number, it’s far more useful to know what’s usual for you. Further, a little month-to-month variation is common. Illness, stress, changes in exercise, energy intake and weight, and different life stages can all make it a little longer or shorter than expected. A ‘regular’ cycle doesn’t mean your period lands on the same date every month, just that it tends to follow a reasonably predictable pattern. And there’s a real difference between feeling regular and actually knowing your numbers: in Hertility’s research, nearly 5% of women who described their cycles as regular and gave a cycle length were, in fact, reporting one outside the 21-35-day range. Which is exactly why knowing your actual figures beats a vague ‘regular’ or ‘irregular’. What counts as an irregular menstrual cycle? For most adults, cycles that are repeatedly shorter than 21 days or longer than 35 are generally considered irregular, but the numbers aren’t the whole story. If your periods always come every 27-30 days and suddenly start arriving every 40, that change is useful information to know. Plenty of things can influence your cycle, and an irregular period doesn’t automatically mean something’s wrong. Common reasons include the first few years after periods begin (most women’s menstrual cycles don’t regulate until they are ~25 years old) , pregnancy, breastfeeding, perimenopause and hormonal contraception, as well as stress, major changes in weight or energy intake, and intensive exercise. Underlying causes include thyroid conditions, raised prolactin and PMOS, along with some medications. If your periods suddenly become irregular, stay that way for several cycles, or come with other symptoms, it’s worth understanding why. If irregular periods, missing periods or symptoms that don’t quite add up sound familiar, our Online Health Assessment is a good first step towards understanding what’s going on. How long should a period last? A period usually lasts 2-7 days, with 5 to 6 days being most common. Some people naturally have short, light periods; others bleed for longer or more heavily, and flow is often heavier on some days than others. There’s no single pattern everyone has to match, what’s useful is knowing what’s normal for you, so a sudden change stands out. What is a normal amount of bleeding during my period? Rather than chasing an exact millilitre figure, the more useful question is simpler: is your bleeding getting in the way of your life? Signs your periods may be heavy include: Heavy periods can also lead to iron-deficiency anaemia, which may leave you unusually tired, dizzy or short of breath. NICE defines heavy menstrual bleeding by its impact on your quality of life rather than a strict volume, so if it’s disrupting your everyday life, that alone is reason enough to get it checked. You don’t have to just cope. What are the phases of the menstrual cycle? The cycle is usually described in four stages, though they overlap rather than switching cleanly: Biologically, there’s a little overlap between these phases. For example, your period actually happens during the beginning of the follicular phase. But thinking about the cycle in four stages is a useful way to picture what’s happening. The follicular phase: from your period to ovulation The follicular phase starts on the first day of your period and ends when you ovulate. For most people, this phase lasts about 10-22 days, but this can vary. At the start of a new cycle, oestrogen and progesterone are low, so the brain releases gonadotrophin-releasing […]