- Both high prolactin (hyperprolactinaemia) and abnormal thyroid function can disrupt ovulation and prevent pregnancy.
- These hormone imbalances are common and treatable causes of infertility.
- Simple blood tests arranged by your GP are the first step to diagnosis.
- Symptoms can be subtle, and difficulty conceiving may be the only sign that something is wrong.
- Effective medications are available to correct these imbalances and significantly improve your fertility.
The Role of Hormones in Conception
Getting pregnant requires a precise sequence of hormonal events, starting in the brain and acting on the ovaries to mature and release an egg. If one of these hormones is out of balance, the entire system can be thrown off course. Two of the most common culprits that can quietly disrupt this process are prolactin and thyroid hormones.
Understanding Prolactin and Its Impact
Prolactin is a hormone produced by the pituitary gland in the brain. Its main job is to stimulate milk production after childbirth, which is why levels are naturally high during breastfeeding. However, if prolactin levels are high when you are not pregnant or breastfeeding (a condition called hyperprolactinaemia), it can suppress the hormones that trigger ovulation.
Essentially, the brain is tricked into thinking you are breastfeeding, so it puts a pause on your reproductive cycle. This can lead to irregular periods or cause them to stop altogether, making conception impossible. Thankfully, this is usually easy to diagnose with a blood test and treat with medication.
The Thyroid's Connection to Ovulation
The thyroid is a gland in your neck that controls your body's metabolism, but its hormones also interact closely with your reproductive hormones. Both an underactive thyroid (hypothyroidism) and an overactive thyroid (hyperthyroidism) can interfere with the signals that tell your ovaries to release an egg. An underactive thyroid is more common and can also cause high prolactin levels.
For women trying to conceive, we like to see the Thyroid Stimulating Hormone (TSH) level at an optimal level, usually below 2.5 mIU/L, even if it is within the 'normal' laboratory range. This ensures the thyroid is functioning perfectly to support ovulation and a future pregnancy.
Getting Tested and Treatment Options
If you have been trying to conceive without success, especially if your cycles are irregular, it is vital to get these hormones checked. A simple blood test, which can be organised through your NHS GP or a private fertility clinic, will measure your prolactin and TSH levels.
The good news is that if a problem is found, the treatment is typically very effective. Simple, safe medications can bring your hormone levels back into the correct range, often restoring normal ovulation and giving you a much better chance of conceiving naturally.
Frequently asked questions
What are the symptoms of high prolactin?
Symptoms can be subtle. They may include irregular or absent periods, a milky discharge from the nipples when not breastfeeding (galactorrhoea), and sometimes reduced libido. Many women have no obvious symptoms other than difficulty conceiving.
Can I get pregnant with an underactive thyroid?
Yes, it is possible, but an undiagnosed or poorly managed thyroid condition, particularly an underactive thyroid (hypothyroidism), can make it much more difficult. It can interfere with ovulation and is also associated with an increased risk of miscarriage. Proper treatment greatly improves your chances of a healthy pregnancy.
Are these hormone tests a standard part of fertility checks?
Yes, a Thyroid Stimulating Hormone (TSH) test and a prolactin test are standard baseline blood tests for anyone struggling to conceive. Your NHS GP can arrange these initial bloods tests for you as part of a first-line fertility investigation.
How are these conditions treated?
Thankfully, both are usually straightforward to treat. High prolactin is typically managed with a medication called cabergoline or bromocriptine, which lowers levels effectively. An underactive thyroid is treated by taking a daily hormone replacement tablet called levothyroxine to bring your TSH into the optimal range for conception.
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