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Explaining The Unexplained:


What is Prolactin?

Prolactin is a hormone that is mainly secreted by your pituitary gland; it is often referred to as the breastfeeding hormone because it is naturally high in nursing women where it has the effect of supressing ovulation. A high level of prolactin is known as hyperprolactinaemia, it is a hidden cause of fertility issues and studies suggest it is a factor for 1 in 10 cases of unexplained infertility.

What Causes a Raised Prolactin Level?

Several lifestyle factors can contribute to a high prolactin level, factors such as a persistent lack of sleep, ongoing high stress levels, depression (and some anti-depressants) and diet.


Running regularly without adequate breast support can also raise prolactin as the excessive amount of movement in the breast tissue set off the mechanism to increase prolactin. If you are a regular runner, make sure to wear a correctly fitted sports bra.

Hyperprolactinaemia can also be caused by a tiny tumour on the pituitary gland – these tumours are rare (approximately 4 people out of every 10,000), usually benign, and their prolactin-generating effect can be controlled with medication. 

How Does a Higher Prolactin Level Affect Fertility?

Prolactin is mainly synthesised in the pituitary gland, which is also responsible for the production of Follicle Stimulating Hormone (FSH); if the pituitary gland is pumping out too much prolactin, this can suppress the production of FSH. FSH is the hormone that signals to your ovary to grow follicles and it plays a key role in the processes leading up to ovulation. In this way, a high prolactin level can have a negative impact on the quality of the developing follicle and egg, and in some cases it can prevent the follicle from maturing to the point where it is able to release an egg.

While it is still possible to fall pregnant while breastfeeding, the high prolactin level in a breastfeeding mum can interfere with ovulation and for many women it provides a degree of protection against pregnancy. If you are searching for a reason for unexplained infertility, it is definitely worth ruling out a high prolactin level.

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Some Signs of High Prolactin
Lack of Cervical Mucus

Hyperprolactinaemia can suppress FSH which will have a knock on effect on the production of oestrogen in the ovary. This in turn will reduce the amount of cervical mucus that is produced; cervical mucus is an essential aspect of your fertility as it enables sperm to move safely through to the egg, protecting and nourishing it as it goes. If you have persistently low levels of oestrogen, or a distinct lack of cervical mucus, it may be time to check your prolactin level.

It is worth mentioning here that there are other causes of reduced cervical mucus. Sometimes cervical mucus production is reduced after a long time on the oral contraceptive pill; Clomid is another cause of reduced cervical mucus. 

Hair Loss

If you notice symptoms of excess hair loss, it may be worth getting your prolactin level checked because high prolactin levels have been linked to high DHEA levels which can in turn lead to an increase in testosterone symptoms.

Testosterone issues (acne, hair loss, irregular cycles)

If you do not ovulate, or have irregular or long cycles (>35 days) it is worth checking prolactin levels – symptoms of high prolactin can mimic some of the testosterone management issues that are frequently associated with polycystic ovarian syndrome (PCOS) as it can cause an increase in DHEA and subsequently an increase in testosterone.

Short Luteal Phase

If your luteal phase is short, or if your progesterone level is a bit low, that may also indicate it is time to check your prolactin level because a raised prolactin level can also shorten and weaken the luteal phase of your cycle.

Producing Breast Milk

Prolactin is known as the breast-feeding hormone because of the role it plays in stimulating the breasts to produce milk. If you have noticed milky secretions from your breasts, you should check your prolactin level.

Other Issues to Check

Hyperprolactinaemia is sometimes associated with other issues such as liver or kidney issues, PCOS or hypothyroidism. If you do find you have high levels of prolactin, you will need to investigate further to determine whether PCOS or hypothyroidism is also involved as both can have a negative impact on your fertility if left undetected. Approximately 1 in 6 people with PCOS also have hyperprolactinaemia.

Checking Your Prolactin Level

Prolactin can be checked easily with a simple blood test. If your GP or fertility clinic runs some blood tests and you have any of the above symptoms, request that they also check your prolactin level. You may have some resistance from your GP because the NICE guidelines recommend prolactin only be checked in women with a known ovulatory disorder, unusual production of breast milk or a pituitary tumour.

If possible, it is best to check your prolactin in the first half of your cycle, in the morning, and avoid excessive nipple stimulation before your test! If your doctor is reluctant to test your prolactin level, you can use a service such as Medichecks who offer a simple finger-prick test to check prolactin:

Very HIGH - Greater than 1000 mIU/L 

If your prolactin level is very high your doctor may refer you for a MRI to check your pituitary gland.

Moderately HIGH - between 480 mIU/L - 1000 mIU/L

A moderately high prolactin level can be caused by thyroid malfunction, alcohol and some types of psychiatric and blood pressure medication.

Mildly HIGH - around 480 mIU/L

If your prolactin level is only mildly raised, you may be advised to have it rechecked. Lots of factors can cause a temporary rise in prolactin, factors such as recent nipple stimulation, stress, mild thyroid issues, exercise and alcohol usage.

Can a High Prolactin Level OK?

If your prolactin level is high, but you have no symptoms of hyperprolactinaemia it is possible that you have high levels of macroprolactin. Macroprolactin is a larger prolactin substance that is counted alongside normal prolactin in the basic test, but macroprolactin levels are not thought to interfere with fertility. Approximately 15% of results showing a high prolactin level are actually caused by a high macroprolactin level.  There is an advanced test which determine how much of a high prolactin level is really macroprolactin, but the test is more expensive and less commonly used.

How to Treat Hyperprolactinaemia

If you have a prolactinoma, you may be prescribed cabergoline or bromocriptine by your doctor; a prolactinoma would usually cause extremely high levels of prolactin (over 1000 mIU/L).

If you have moderately elevated prolactin, evidence suggests that Vitex (agnus castus) has a prolactin-lowering effect, equally as effective as Bromocriptine. Vitex effects hormone production by disrupting the function of the pituitary gland, it is not a herbal supplement to stay on for a long period of time and I recommend you consult a qualified herbalist before taking it. In her brilliant book '8 Steps to Reverse Your PCOS', Fiona McCulloch suggests taking Vitex for between 3-6 months can help to reset prolactin levels – take daily with a break of 5 days a month. Once ovulation normalises and your cycle is regular, adjust the timing so that you only take it during the luteal phase of the cycle.

One study of a group of women with hyperprolactinaemia showed that when they took Vitex for 3 months, their average luteal phase increased from 3.4 days to 10.5 days (Arentz S. et al, 2014).


Stress is a contributing factor to hyperprolactinaemia, so put some concerted effort into working out how to manage your stress and encourage a more mindful, relaxed state of mind. Meditation, mindfulness, yoga and gentle walking are all good habits to adopt and if you know stress is a significant factor for you, commit regular time for activities such as these..


Keep Off the Beer!

Reduce your alcohol intake, but it is particularly important to avoid beer. Beer was traditionally given to nursing women to encourage breast feeding as components of beer can help to increase prolactin.


Work With Specialist Fertility Acupuncturist

When dealing with unexplained infertility, you may find your battle much easier if you enlist the help of a Specialist Fertility Acupuncturist. We are a group of highly trained acupuncturists with a special interest and in depth training in working with infertility.


The body has an innate ability to want to heal, acupuncture has an incredibly long history of encouraging and enabling such healing. Use our knowledge to help work out why your fertility is struggling, and our skills to support you to gently nourish and improve your fertility. We can help you to sift through the maze of fertility information you will find here and elsewhere, work out what tests you should consider, help you to interpret the results and formulate a plan to get things moving in the right direction.

Why Work With a Fertility Support Trained Acupuncturist - Click Here

How Do I Find a Fertility Support Trained Acupuncturist - Click Here



Arentz S, Abbott JA, Smith CA, Bensoussan A. Herbal medicine for the management

of polycystic ovary syndrome (PCOS) and associated oligo/amenorrhoea and hyperandrogenism;

a review of the laboratory evidence for effects with corroborative clinical findings.

BMC Complement Altern Med. 2014;14:511. Published 2014 Dec 18. doi:10.1186/1472-6882-14-511

Reading List

Period Repair Manual; Lara Briden ND

Taking Charge of Your Fertility; Toni Weschler MPH

8 Steps to Reverse Your PCOS; Fiona McCulloch ND

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