Day 3 Fertility Blood Test, from our experts to you.
Dr Natasha Fernando MBBS, MRCGP

Medical Director

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What is a
fertility blood test?

Our day three fertility test is a helpful first test in an investigation into female infertility. Ideally, you should take our test three days after the start of your period, but it can also be taken on days two, four, or five of your menstrual cycle. This test aims to check that hormone levels can support the maturation and release of a healthy egg from the ovary.

What can I learn
from this test?

Our test includes Follicle-stimulating hormone (FSH), luteinising hormone (LH), and oestradiol. FSH is released from a gland in your brain (the pituitary gland) to stimulate the ovary to start maturing an egg. LH is required for the final maturation and release of the egg from a follicle (a fluid-filled sac containing the egg), while the hormone oestradiol stimulates the growth of the follicle and prepares the womb lining for pregnancy.

The levels of hormones in your body on day three of your cycle can indicate whether hormonal problems are likely to affect ovulation and conception and whether a condition like polycystic ovaries may be affecting fertility.

What could
affect my results?

Please note that any hormones you are taking for contraception or hormone replacement therapy (HRT) will influence your results. If you are looking for a true picture of your fertility status then please take this test at least 12 weeks after stopping any hormone replacement or contraceptive pill, implant or hormone IUD. It is recommended to wait until your periods have re-established a regular cycle (for you) before taking this test.

What's Included?

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FSH Follicle Stimulating Hormone (FSH) is produced in the pituitary gland and is important for women in the production of eggs by the ovaries and for men for men in the production of sperm. In the first half of the menstrual cycle in women, FSH stimulates the enlargement of follicles within the ovaries. Each of these follicles will help to increase oestradiol levels. One follicle will become dominant and will be released by the ovary (ovulation), after which follicle stimulating hormone levels drop during the second half of the menstrual cycle. In men, FSH acts on the seminiferous tubules of the testicles where they stimulate immature sperm cells to develop into mature sperm.
LH Luteinising Hormone (LH) is produced by the pituitary gland and is important for male and female fertility. In women it governs the menstrual cycle, peaking before ovulation. In men it stimulates the production of testosterone.
Oestradiol Oestradiol is a female steroid hormone, produced in the ovaries of women and to a much lesser extent in the testes of men. It is the strongest of three oestrogens and is responsible for the female reproductive system as well as the growth of breast tissue and bone thickness. In pre-menopausal women, oestradiol levels vary throughout the monthly cycle, peaking at ovulation. In women, oestradiol levels decline with age, culminating with the menopause when the ovaries stop producing eggs. Low oestradiol can cause many symptoms associated with the menopause, including hot flushes, night sweats and mood swings. Low oestradiol can also cause osteoporosis.

How to prepare
for your test

Special Instructions

Prepare for your Day 3 Fertility Blood Test by following these instructions. Take this test two to five days after the start of your period, ideally on day three. It can be taken any time if you do not have periods. Hormonal contraception can affect this test, taking a break from this and using barrier contraception will give more accurate results. If you use hormone gels, pessaries, patches, or tablets, we strongly recommend selecting a venous sample to minimise contamination sometimes seen with finger-prick tests. Otherwise, administer any hormone supplements using gloves, and make sure your fingers have not been in contact with hormone supplements for at least four weeks before taking the test. Hormones can be absorbed deep within the skin even after minimal contact and remain there for weeks despite vigorous handwashing. Do not take biotin supplements for two days before this test, discuss this with your doctor if it is prescribed.