Female Fertility Test

You do not need to stop taking oral contraceptives on that day, and if you are taking any specific thyroid monitoring treatment, it is preferable to have the sample taken before taking the dose for that day.

The thyroid is an endocrine gland that produces hormones important for regulating metabolism and cell growth. A malfunctioning thyroid can affect female fertility in several ways:

1. Ovulation problems: The thyroid produces hormones that are essential for ovulation. If the levels of these hormones are imbalanced, it can cause problems with ovulation, which reduces the chances of getting pregnant.
2. Implantation problems: Thyroid hormones also play an important role in the process of embryo implantation in the uterus. If the levels of these hormones are imbalanced, it can affect the embryo's ability to implant in the uterus.
3. Alterations in the menstrual cycle: Thyroid disorders can alter the length and regularity of the menstrual cycle, making it difficult to identify fertile days and plan sexual intercourse at the right times to conceive.
4. Miscarriage: Women with untreated thyroid disorders have an increased risk of miscarriage in early pregnancy, so it is recommended that women with fertility problems have their thyroid function checked.

A woman is born with approximately 2,000,000 primary follicles. Thereafter, the ovary remains inactive until puberty, when about 300,000 remain, with about 1,000 dying each month during a woman's fertile years. After the age of 35, the chances of achieving a spontaneous pregnancy decrease significantly as the number of follicles drops drastically, as does the quality of the oocytes due to reproductive ageing, reaching the menopause with very low oestrogen levels.

Anti-Müllerian hormone (AMH), which is the hormone we use to estimate ovarian reserve, remains relatively stable throughout the hormonal cycle. Therefore, you can take the test at any time, without having to wait for a specific phase. However, recent studies have found that values may vary slightly (around 10 %) depending on the phase of the cycle: they are usually slightly higher in the early follicular phase (first days of the cycle) and slightly lower in the luteal phase. This difference does not usually change the interpretation of the results, but if you want maximum consistency - for example, to compare results over time - you may prefer to do it in the early days of the cycle. As for TSH, which tests thyroid function, it does not vary significantly throughout the cycle, so it can be measured at any time.

There is no single interval for all women. How often you should repeat a fertility test depends mainly on your age, your previous results and your clinical situation. If your AMH and TSH results are normal and there are no changes in your health, repeating the test every 12-18 months is a reasonable practice.

Medical guidelines advise that TSH should be below 2.5 mIU/L in the pre-pregnancy period to optimise the chances of conception and reduce early risks. It has also been shown that TSH values between 2.5 and 4 mIU/L do not necessarily delay pregnancy, although being below 2.5 mIU/L is still recommended.