Understanding Fertility Hormones: The Blood Tests Behind IVF and Trying to Conceive

Fertility treatment in the UK has grown steadily over the past decade, and with it, so has demand for the blood tests that sit behind every fertility journey. Whether you are trying to conceive naturally, preparing for IVF, or simply want to understand your reproductive health, hormone testing is one of the clearest windows into what is happening inside your body.

At VitaLync Diagnosis, we have seen a marked rise in requests for reproductive hormone panels, particularly progesterone (PRG), luteinising hormone (LH) and human chorionic gonadotropin (hCG). This guide explains what these hormones do, why they matter for fertility and IVF, and which tests can give you the answers you need.

Our testing is carried out by our partner laboratory, Medical Diagnosis, a UKAS ISO 15189 accredited lab, and no GP referral is required.

Why fertility hormone testing matters

Conception depends on a finely tuned sequence of hormonal signals. The brain, pituitary gland and ovaries or testes all communicate through hormones to mature an egg, trigger its release, prepare the womb, and support an early pregnancy. When one part of that chain is out of balance, conception can become difficult.

Hormone blood tests help identify where a problem might lie. For women, they can reveal whether ovulation is happening, assess ovarian reserve, and flag conditions such as polycystic ovary syndrome (PCOS) or thyroid imbalance. For men, they can point to issues with testosterone production or sperm development. Roughly speaking, a sperm-related factor contributes to a large share of couples' fertility difficulties, so testing both partners often makes sense.

If you would like to explore the full range, our fertility blood tests and hormone blood tests categories list every individual marker and panel we offer.

The three hormones we are asked about most

Progesterone (PRG)

Progesterone is the hormone of the second half of the menstrual cycle. After ovulation, the follicle that released the egg becomes the corpus luteum and produces progesterone, which thickens the lining of the womb in preparation for a fertilised egg to implant. If pregnancy occurs, progesterone helps sustain it in the early weeks.

Because progesterone rises after ovulation, a well-timed progesterone test (often around day 21 of a 28-day cycle) is one of the simplest ways to confirm whether ovulation has taken place. Low progesterone can point to problems with ovulation or with maintaining an early pregnancy, which is why it is a key marker in fertility investigations and in monitoring some fertility treatments.

Luteinising hormone (LH)

Luteinising hormone is produced by the pituitary gland and is central to reproduction in both sexes. In women, a mid-cycle surge in LH is what actually triggers ovulation, the release of a mature egg from the ovary. Tracking LH therefore helps identify the fertile window and can reveal ovulation disorders. Abnormal LH levels are also part of the picture in conditions such as PCOS.

In men, LH stimulates the testes to produce testosterone, which is essential for healthy sperm production. Abnormal LH in men can signal an issue with testosterone production or testicular function.

LH is rarely interpreted alone. It is usually assessed alongside follicle-stimulating hormone (FSH), and often with oestradiol, progesterone and testosterone, to build a complete reproductive profile. Our FSH-LH Profile fertility blood test pairs these two pituitary hormones together, and our Menstrual Cycle and Ovulation Control panel tracks the hormones across the cycle for a fuller view.

Human chorionic gonadotropin (hCG)

hCG is the hormone produced once an embryo implants in the womb, it is the hormone that pregnancy tests detect. In fertility care, blood hCG testing is more sensitive than a home urine test and can confirm pregnancy earlier and more precisely. In IVF, quantitative (numerical) hCG blood tests are used after embryo transfer to confirm implantation and to monitor whether levels are rising as expected in the earliest days of pregnancy.

Where IVF fits in

IVF and other assisted-conception treatments rely heavily on hormone monitoring at every stage. Before a cycle begins, baseline hormone tests, including FSH, LH, oestradiol and often anti-Müllerian hormone (AMH), help clinicians understand ovarian reserve and plan the right approach. During ovarian stimulation, hormones are tracked closely to time egg collection.

After embryo transfer: progesterone and hCG monitoring

The period after embryo transfer, often called the "two-week wait", is where we see the fastest-growing demand for private testing, and it centres on two hormones working together: progesterone (PRG) and hCG.

Progesterone matters after transfer because it maintains the womb lining and supports the pregnancy in its earliest days. Many IVF patients are on progesterone support (pessaries or injections), and checking progesterone levels helps confirm that support is adequate. hCG, meanwhile, is the hormone that confirms whether an embryo has implanted, a quantitative blood hCG test is far more precise than a home urine test, and repeat readings show whether levels are rising as they should in a healthy early pregnancy.

Testing these two markers together, at the right moment after transfer, gives a clearer picture of whether a cycle has been successful and whether the early pregnancy is progressing. Because timing is so important during the two-week wait, many people going through IVF value being able to arrange a quick, reliable progesterone and hCG blood test privately, without waiting for a clinic slot, and then share the results with their fertility team.

Having reliable, quick blood results throughout this process matters. Many people preparing for or going through IVF choose to test privately so they can get baseline readings without delay, or keep an eye on specific markers between clinic appointments.

Fertility profiles at VitaLync Diagnosis

Individual markers are useful, but for most people a profile, a ready-made panel of the most relevant hormones, gives a clearer picture. Our most popular fertility panels include:

• Infertility Profile, Female: evaluates the key reproductive hormones affecting ovulation and fertility, including FSH, LH, prolactin, oestradiol and progesterone.
• Infertility Profile, Male: assesses the hormones behind male fertility and sperm production, ideal for men undergoing fertility investigations.
• FSH-LH Profile: a focused look at the two pituitary hormones that regulate the cycle and ovulation.
• Menstrual Cycle and Ovulation Control: tracks the hormones that govern the cycle to help pinpoint ovulation.
• Antenatal Profile: a comprehensive early-pregnancy screen for those who have conceived.
• Women's Hormones: a broad hormone overview for women wanting a fuller reproductive-health assessment.

If you suspect an underlying condition such as PCOS, our Polycystic Ovary Syndrome Profile may be more appropriate, while our full list of health profiles covers thyroid, testosterone and more, all of which can influence fertility.

How to get tested, the options

We have made testing as convenient as possible, whether you prefer to visit us or test from home:

• At a clinic: book any test and attend one of our clinics for a professional blood draw. Browse the fertility category and book online.
• At-home test kits: order a kit online, collect your sample at home, and return it to the lab. A convenient option for those with busy schedules or who prefer privacy.
• Mobile phlebotomy: our trained phlebotomists can come to your home or workplace to take your sample.

If you would like to talk through your results or which test is right for you, our GP consultation service connects you with a GMC-registered doctor, in person or online.

A note on timing

Fertility hormones fluctuate across the menstrual cycle, so timing your test correctly is important. Progesterone is typically measured about seven days after ovulation (around day 21 of a 28-day cycle), while FSH and LH are often tested early in the cycle (around day 2 to 5). If your cycle is irregular, or you are unsure when to test, speak to us and we can help you plan the right timing.

Take the first step

Understanding your hormones is one of the most empowering things you can do when trying to conceive or preparing for IVF. Clear, accurate results give you and your clinician the information needed to make good decisions, whether that is reassurance that everything is on track, or an early flag that lets you act sooner.

Explore our fertility blood tests and fertility profiles, or book an at-home kit today. All testing is carried out to UKAS ISO 15189 standards, with no GP referral needed.

This article is for general information and does not replace personalised medical advice. If you have concerns about your fertility, please speak to a healthcare professional. VitaLync Diagnosis works with Medical Diagnosis, a UKAS ISO 15189 accredited laboratory; clinical services are provided by GMC-registered doctors through Medical Diagnosis Victoria, which is registered with the Care Quality Commission (CQC).