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Hormones 101: Prolactin in fertility testing

Prolactin in fertility testing – we tell you what you need to know. This blog explains why we’ve included prolactin in our hormone test panel.

We believe in debunking myths around fertility science. Our experts have written the ‘Hormone 101’ series to explain each hormone in our test panel, and how it’s connected to fertility. This is part of our mission to empower women with data and knowledge about their bodies.

What is prolactin?

Prolactin, also known as ‘luteotropic hormone’ or ‘luteotropin’, is a hormone produced by the pituitary gland as well as the uterus, immune cells, breasts and prostate. It’s most well-known as the ‘milk hormone’ since it’s responsible for lactation. Prolactin also regulates important functions in the body including fluids, the immune system and behavioral function.

Normally, prolactin production happens after things like eating, taking estrogen birth control, having sex, ovulation, and nursing.

Why include prolactin in fertility tests?

Higher levels of prolactin (hyperprolactinemia) can affect fertility by disrupting your menstrual cycle and ovulation. If prolactin levels are too high, you may ovulate intermittently, rarely or not at all. This limits your fertile window and ability to conceive. You may also experience an irregular menstrual cycle.

Some women might have a ‘luteal phase defect’, where mildly elevated prolactin levels can cause progesterone to be under-produced after ovulating. This deficiency in progesterone can make the uterine lining a place where the embryo is less likely to implant, causing difficulty conceiving.

In short, prolactin can affect ovulation. Ovulation impacts your ability to get pregnant.

How can you tell if your prolactin levels are too high?

Primarily by testing the levels of prolactin in your blood. However, higher prolactin levels can sometimes cause symptoms like irregular periods, or breast discharge in non-pregnant women. Breast discharge happens because the prolactin hormone stimulates milk production in women. This can discourage ovulation and impact fertility.

What causes high prolactin levels?

Prolactin levels are naturally higher after ovulation. This is one of the reasons we ask you to take the hormone test on Day 3 of your menstrual cycle.

Sometimes, blood pressure medication, estrogen birth control and ‘the pill’ can cause higher levels of prolactin. Normally, your prolactin levels will go back to normal once you’ve stopped taking the medicine. If you’re on any medicine you think could affect your levels, talk to one of our experts before doing your test.

Sometimes, conditions like PCOS can also cause women to produce higher levels of prolactin. That’s not to say all women with PCOS will have high prolactin levels. It’s important to take a test so you know for sure. Hypothyroidism (an under-active thyroid) can also cause high levels of prolactin. Because these hormones are interlinked, we’ve included a thyroid function test for TSH and T4 in our hormone test panel. You can read more about the link between thyroid and fertility in our blogs about TSH and T4.

What if my report shows high prolactin levels?

When you take a hormone test with Adia, we send you a personalized report explaining your results. If any of your results are outside the reference range, please don’t worry – speak to one of our experts (or your GP) about this. Understanding your hormone health is the first step. Once you know what your levels are, you can discuss next steps with our expert team.

Higher levels of prolactin can be treated, but the treatment depends entirely on what’s causing the imbalance. It’s important to understand your hormone health, so you know what to do next.

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Read other blogs in our ‘Hormones 101’ series: