The Major Pregnancy Hormones


Ahhh pregnancy hormones – don’t we just love them? From taking you on an emotional rollercoaster ride, to skin problems and nausea, they can certainly make life interesting for mums-to-be.

So what are main pregnancy hormones that come to play as your pregnancy progresses?

The Major Pregnancy Hormones

HCG is the key hormone present during pregnancy and what gets tested to produce that big fat positive on your pregnancy test. It maintains secretion of oestrogen and progesterone by the corpus luteum in the ovary until the placenta takes over.

HCG levels typically double every 2-3 days during the first 10 weeks of your pregnancy, peaking at around 10-12 weeks before gradually declining.

Oestrogen is secreted by the corpus luteum until the placenta takes over. Increasing levels serve to boost blood flow to your body’s organs, promote the development of your breasts and uterus, and soften the collagen fibres in your connective tissues helping your ligaments become more flexible.

It also helps stimulate hormone production in your baby’s adrenal gland.

Until about weeks 6-8, progesterone is produced by a cyst on your ovary called the corpus luteum to help maintain the pregnancy. This function is then taken over by the placenta by around the end of the first trimester.

Progesterone relaxes your blood vessels to help them cope with the increased blood flow in your body; also having similar relaxing effects on your digestive and urinary tracts.

Importantly, this overall loosening effect on tendons and ligaments helps your body to accommodate your growing uterus, and also helps prevent contractions until birth is due.

HPL is produced by the placenta from about five weeks onwards, and the levels rise during pregnancy. HPL blocks your body’s insulin from transporting glucose stores into your cells; and helps divert glucose stores to your baby to allow it to get the glucose it needs to grow.

It also has a role in breast development the secretion of milk after delivery.

Prolactin is the milk-producing hormone, produced in the anterior lobe of the pituitary gland in the brain.

Levels increase during pregnancy to stimulate your breasts to produce milk after delivery.

Relaxin is produced by the ovaries and increases by about 10 times normal levels during pregnancy.

This pregnancy hormone helps to soften the pelvic ligaments, and prepare the cervix for delivery.

Oxytocin is a hormone that causes the muscles of the uterus to contract.

It is produced by the posterior lobe of the pituitary gland. Levels tend to rise during labour.

Cortisol has a role in helping the lungs of the fetus mature, with levels increasing from around the end of the first trimester onward.

Testosterone produced by the fetal adrenal glands is needed for the development of the male genitalia.


Copyright 2016

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2 Comments on "The Major Pregnancy Hormones"

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5 years 3 months ago

This is really helpful, thanks for this DearBub!

DearBub Staff Authors
5 years 2 months ago

You’re welcome Jenny!