When couples think about fertility, they often focus on lifestyle factors, timing, or even stress levels. But behind the scenes, hormones orchestrate the entire reproductive process — from egg development and ovulation to sperm production and successful implantation. When hormones are out of balance, fertility can suffer, often without obvious symptoms.
Blood tests provide a window into this hidden hormonal world, revealing imbalances that may be affecting your ability to conceive. Whether you are just starting your fertility journey or have been trying for some time, understanding what your blood tests can reveal is empowering.
The Hormonal Orchestra of Fertility
Reproduction depends on a complex interplay of hormones working in precise coordination. In women, the monthly cycle involves carefully timed rises and falls of multiple hormones. In men, steady hormone levels are essential for continuous sperm production.
When any part of this system is disrupted, fertility can be affected — sometimes dramatically, sometimes subtly.
Key Fertility Hormones in Women
### Follicle-Stimulating Hormone (FSH)
FSH stimulates the ovaries to develop follicles (eggs). It is a key indicator of ovarian reserve — the quantity and quality of remaining eggs.
What FSH levels indicate:
When to test: Day 2-4 of the menstrual cycle for baseline assessment.
### Luteinising Hormone (LH)
LH triggers ovulation. The mid-cycle LH surge causes the mature egg to be released from the ovary.
What LH levels indicate:
### Oestradiol (E2)
Oestradiol is the primary form of oestrogen during reproductive years. It promotes follicle development and prepares the uterine lining for implantation.
What oestradiol levels indicate:
### Anti-Müllerian Hormone (AMH)
AMH is produced by developing follicles and provides the most direct measure of ovarian reserve.
What AMH levels indicate:
Advantage: AMH can be tested at any point in the menstrual cycle.
### Progesterone
Progesterone rises after ovulation and is essential for maintaining early pregnancy.
What progesterone levels indicate:
When to test: Day 21 of a 28-day cycle (7 days post-ovulation).
### Prolactin
Prolactin is primarily associated with breastfeeding, but elevated levels can suppress ovulation.
What elevated prolactin may indicate:
Key Fertility Hormones in Men
### Testosterone
Testosterone is essential for sperm production, libido, and overall male reproductive health.
What testosterone levels indicate:
### FSH and LH in Men
In men, FSH stimulates the testes to produce sperm, while LH stimulates testosterone production.
What levels indicate:
### Prolactin in Men
Elevated prolactin in men can suppress testosterone and impair fertility.
Thyroid Function and Fertility
Thyroid hormones profoundly affect fertility in both men and women. Even subtle thyroid dysfunction can impair conception.
In women:
In men:
For comprehensive thyroid information, read our guide to private blood tests for thyroid problems.
Other Important Tests
### Vitamin D
Vitamin D receptors are found in reproductive tissues, and deficiency has been linked to reduced fertility in both sexes.
### Iron and Ferritin
Iron deficiency can affect ovulation and may increase miscarriage risk.
### Insulin and Glucose
Insulin resistance is closely linked to PCOS, a leading cause of female infertility. For more information, read our guide to understanding the A1C blood test.
### Inflammation Markers
Chronic inflammation can affect fertility. Testing CRP and other markers may provide useful information. Learn more in our overview of the C-reactive protein test.
When to Consider Fertility Blood Tests
For comprehensive information about hormone testing, read our article on hormone imbalance symptoms you should not ignore.
Understanding Your Results
Fertility hormones must be interpreted in context:
Fertility Hormone Testing in London
At Private Blood Tests London, we offer comprehensive fertility hormone panels for both women and men at our CQC-registered clinic in South Kensington. Our tests provide detailed insights into your reproductive hormone health, helping you understand your fertility and plan accordingly.
For related testing, explore our [thyroid function tests](/thyroid-test) and [comprehensive health screening packages](/health-screening).
Whether you are planning ahead or actively trying to conceive, knowledge is power. Book your fertility hormone test today.