Prolactin: Function and Normal Levels

Have you seen the word “prolactin” pop up in books about pregnancy and childbirth? In general, it’s explained as the hormone that stimulates milk production and allows breastfeeding. However, it also has other effects: notably, if you’ve got high prolactin levels, this means it’s difficult to get pregnant. Let’s take a run through what prolactin is and the effects it has on the female body.

What does prolactin do?

breastfeeding lactation baby newborn

Prolactin (also known as luteotropic hormone or LTH) is a hormone secreted by the pituitary gland to prepare the body for breastfeeding after the birth of a child. It has two main functions to support the newborn’s development.

Develop the mammary glands

Prolactin supports the development of the mammary glands in order to allow breastmilk production. After birth, the mammary glands are soon flooded with the hormone oxytocin (also known as the “love hormone”) is secreted, which allows for the let-down of milk through the nipple.

These two hormones work together to allow breastfeeding: when the baby suckles, the stimulation triggers the production of even more prolactin and oxytocin, continuing the cycle of milk production and let-down.

Suppressing ovulation

After giving birth, prolactin suppresses ovulation to put the kibosh on any further pregnancy. Producing breastmilk and taking care of the newborn puts enough of a burden on the mother’s body as it is, so to prevent any new pregnancy adding to it, prolactin temporarily halts ovulation.

Imagine it like a factory foreman saying to the rest of the body, “We’ve got one hungry baby situation here already – we don’t need another one any time soon!” That said, that doesn’t mean breastfeeding is foolproof contraception thanks to prolactin: The effect wears off after a couple of months as your menstrual cycle returns to normal, even if you are still breastfeeding. Take additional contraceptive measures if you don’t want to become pregnant.

How much prolactin is normal?

doctor patient woman

Prolactin levels can be measured by a simple blood test. The normal prolactin level in the bloodstream for non-pregnant women is 3 to 30ng/mL, 10 to 209ng/mL during pregnancy, and 2 to 20ng/mL after menopause. Among its other functions, prolactin appears to play a role in the immune system, so you will always have a baseline level even if you aren’t pregnant.

If you’re trying to conceive, prolactin levels should be 15ng/mL or less. However, if prolactin levels are elevated outside of pregnancy or lactation, it could point to a condition called hyperprolactinemia. This can result in infertility, menstrual irregularities and anovulation.

The usual cut-off for hyperprolactinemia in non-pregnant, non-lactating women is defined as over 30ng/mL. Elevated prolactin levels can also trigger a range of physical changes like galactorrhea: a milky discharge from the nipples – even if you’ve never been pregnant. Or even if you’re a man, for that matter.

Hormone balance matters!

breast feeding woman baby mother

Prolactin is an essential for pregnancy, birth and childrearing, but it’s certainly not the only one at play. Your hormones all work together in a delicate balance to regulate your body’s systems, and for optimum health and fertility, it’s important to maintain that balance. By leading a healthy lifestyle and keeping stress levels in check, you’ll give yourself the best chance for healthy hormone balance.