Trying for a baby can make every cycle feel significant, particularly when periods are irregular, conception is taking longer than expected, or you simply want clearer answers. The top blood tests for fertility can provide a valuable picture of hormones, ovulation, ovarian reserve and wider health factors that may affect your plans. They are not a verdict on whether pregnancy will happen, but they can help you and your clinician decide what to explore next.
At Miracle Scan, we understand that fertility testing is personal. A thoughtful, clinically led approach means looking at the whole picture – your medical history, cycle pattern, symptoms, age, scan findings where appropriate and your results together.
Why fertility blood tests can be helpful
Blood tests measure substances circulating in the bloodstream, including reproductive hormones and markers of metabolic or thyroid health. Depending on the test, they may indicate whether ovulation is likely to be occurring, how the ovaries may respond to stimulation during fertility treatment, or whether a hormonal imbalance needs further assessment.
Timing matters. Some hormones are most informative early in the menstrual cycle, while others are best checked after ovulation. A result also needs context: a single level can vary between cycles, and reference ranges alone do not tell the full story. This is why results should be reviewed by a qualified healthcare professional rather than interpreted in isolation.
Top blood tests for fertility in women
AMH for ovarian reserve
Anti-Müllerian hormone, or AMH, is one of the most commonly requested fertility blood tests. It is produced by small follicles in the ovaries and is used as an indication of ovarian reserve – the remaining supply of eggs capable of developing.
AMH can usually be tested at any point in the cycle. A lower result may suggest a lower ovarian reserve, while a higher result can be seen in people with polycystic ovary syndrome (PCOS). Neither result confirms natural fertility, egg quality or the precise chance of pregnancy. Age remains one of the strongest influences on egg quality, and AMH is particularly useful when considered alongside an antral follicle count on ultrasound.
FSH, LH and oestradiol
Follicle-stimulating hormone (FSH), luteinising hormone (LH) and oestradiol are often measured together, usually between days two and five of a menstrual cycle. FSH helps stimulate follicle development, LH plays a central role in ovulation, and oestradiol is a form of oestrogen produced by developing follicles.
These results can offer clues about ovarian function and hormone signalling. For example, an elevated early-cycle FSH may warrant further discussion about ovarian reserve, while a pattern of raised LH relative to FSH can occur with PCOS. However, hormone patterns are not diagnostic on their own. Symptoms, ultrasound findings and repeat testing may all be relevant.
Progesterone to confirm ovulation
Progesterone rises after ovulation. Testing it at the right point in the cycle can help establish whether ovulation is likely to have occurred. It is often referred to as a “day 21 progesterone” test, but day 21 is only suitable for someone with a regular 28-day cycle.
For more accurate timing, progesterone is generally checked around seven days before the next expected period. If cycles are long, short or unpredictable, a clinician may advise a different date or repeat testing. A result should not be used to judge the quality of a pregnancy or to self-prescribe progesterone treatment.
Prolactin
Prolactin is a hormone best known for supporting breast milk production after birth. When levels are persistently raised outside pregnancy or breastfeeding, it can interfere with ovulation and cause irregular periods, absent periods, breast discharge or reduced libido.
Stress, recent exercise, breast stimulation and some medicines can temporarily raise prolactin. If a result is unexpectedly high, it may need repeating under carefully advised conditions before any conclusions are drawn.
Thyroid function tests
Thyroid hormones influence menstrual regularity, ovulation and pregnancy health. A thyroid panel commonly includes thyroid-stimulating hormone (TSH), with free thyroxine (FT4) added where indicated. Thyroid antibody tests may also be considered for some patients, particularly where there is a personal or family history of thyroid disease or recurrent pregnancy loss.
Both an underactive and overactive thyroid can affect reproductive health. The right follow-up depends on the result, symptoms and whether you are already taking thyroid medication.
Androgen and metabolic testing for PCOS symptoms
If you have acne, excess facial or body hair, scalp hair thinning, weight changes, infrequent periods or difficulty identifying ovulation, blood testing may investigate PCOS and related metabolic factors. Tests can include testosterone, sex hormone-binding globulin (SHBG), a calculated free androgen index and, in selected cases, DHEAS or other adrenal hormones.
A clinician may also recommend HbA1c, glucose testing or a lipid profile. PCOS is not diagnosed from one blood result. It is assessed using a combination of symptoms, hormone results and ovarian appearance on ultrasound, while excluding other possible causes.
Fertility blood tests for men
Fertility is shared, so testing should not rest solely on one partner. A semen analysis is usually the first-line investigation for male-factor fertility because it examines sperm concentration, movement and shape. Blood tests can be useful when there are symptoms of hormonal imbalance, a low sperm count, erectile difficulties, reduced sexual desire, testicular concerns or a relevant medical history.
A male hormone profile may include testosterone, FSH, LH, prolactin and SHBG, with additional tests selected when needed. These results can help identify whether hormonal signalling may be affecting sperm production, but normal blood results do not rule out sperm-related issues. Semen testing and clinical assessment remain essential.
Tests sometimes needed before IVF or other treatment
If you are planning IVF, IUI or another assisted conception pathway, a clinic may request further blood tests. These can include full blood count, blood group and rhesus status, and screening for infections such as hepatitis B, hepatitis C and HIV. These tests are important for safe treatment planning, laboratory procedures and pregnancy care, but they do not measure fertility itself.
Vitamin D may also be included in some private fertility panels. Correcting a genuine deficiency supports general health, but a vitamin D result should not be presented as a standalone explanation for infertility.
Preparing for your appointment and results
Before arranging testing, share details of your cycle dates, current medication, hormonal contraception, supplements, previous pregnancies and any known health conditions. Hormonal contraception can affect the interpretation of several fertility markers, while pregnancy, breastfeeding and recent miscarriage can also change results.
Ask when each sample should be taken and whether you need to fast. Most reproductive hormone tests do not require fasting, although glucose or lipid testing may. It is also sensible to avoid making major decisions based on a single unexpected result. Your clinician may suggest repeating the test, arranging a pelvic ultrasound, reviewing a semen analysis or referring you to a fertility specialist.
When to seek fertility advice
It is reasonable to ask for advice after 12 months of regular unprotected sex without pregnancy if you are under 35. If you are aged 35 or over, seeking assessment after six months is often advised. Earlier review is appropriate if periods are absent or very irregular, there is known endometriosis or PCOS, previous pelvic infection or ectopic pregnancy, recurrent miscarriage, prior chemotherapy, testicular surgery, or an established concern about sperm health.
Private blood testing can offer timely information, but the most reassuring next step is not always more tests. Sometimes it is a carefully timed progesterone result; sometimes it is an ultrasound scan to assess the uterus and ovaries; sometimes it is ensuring both partners are assessed early. Clear, compassionate interpretation gives each result its proper place and helps you move forward with confidence and care.