Everything You Need To Know About Pregnancy Hormones

OK, are you sitting down for this? We're about to look into the wild and weird world of pregnancy hormones. From the very first moment of conception, your amazing female body starts to release a multitude of hormones. These hormones help your body to grow and expand, and help your baby to grow all the limbs, digits, organs and so on that they need to survive out in the real world. Those hormones are also responsible for how you feel, how well you sleep, and so much more. Let's get into it.

Human Chorionic Gonadotropin (HCG): The Pregnancy Hormone

This is the one that shows up on those pregnancy tests you buy in the store. It's created by the cells formed in the placenta and feeds the egg after it has attached to the wall of the uterus. The hormone hCG will peak in the first 8-11 weeks, and will then level off. Once hCG is detectable, it is rare that pregnancy is not present.


Oestrogen, sometimes spelled Estrogen, is the growth hormone responsible for the expansion of the uterus, increasing blood flow, releasing other important hormones, growing your breasts and preparing them to lactate, and helps with the development of the baby. Oestrogen also contributes towards:

Increased blood flow, giving you the pregnant 'glow', but can also cause a stuffy nose, postnasal drip and headaches

Hyperpigmentation, which can result in the 'linea alba' or white line, that runs downwards from your belly button, as well as darkening the areola of your nipples.

Can cause nausea in early pregnancy and make the ligaments softer, causing lower back pain early on.


This one works in tandem with Oestrogen and is also produced in the ovaries. It contributes to the growth of the placenta and the endometrium and helps to ensure that the smooth muscle of your uterus is able to expand to accommodate your growing baby. To do that, Progesterone helps to:

Soften cartilage, loosen joints and ligaments and prepare the body for labour.

It can also produce swelling in the gums and acne.

Causes an increase of blood flow to the womb, which could also be responsible for heartburn, reflux, gas and constipation.

Strengthens the pelvic floor muscles for labour and prevents your body from producing milk until your baby is born.

Placental Growth Factor

This hormone helps to ensure blood vessel growth between your uterus and your placenta, ensuring a healthy flow of blood to the growing baby. Low levels of placental growth factor have been associated with Preeclampsia.


This lovely hormone is responsible for letting it all go, well, your muscles and ligaments at least. Relaxin is what your body secretes in the third trimester to help your body prepare for delivery. It helps your smooth uterine muscle relax and your cervix dilates, but it can make you a bit wobbly so be careful of falling as you near term.

Human Placental Lactogen

This fun hormone is also known as Human Chorionic Somatomammotropin and helps to prepare your breasts for lactation. It's responsible for the secretion first of colostrum and then of breast milk. It also changes the maternal metabolism to ensure that the correct balance of fatty acids, glucose and so on are absorbed to feed the growing baby.


This jolly hormone is also known as the Luteotropic hormone and is responsible for milk production by stimulating the mammary glands. It's released when you hold your baby and when baby feeds (therefore, the more baby feeds, the more milk you will produce). It can also have an effect on the adrenal glands which can result in excessive hair growth in weird places. That should abate after delivery, though.


This lovely one is released during labour and when you are skin-to-skin with your baby. It's also known as the 'love' hormone and helps to reduce the pain of labour, helping your cervix to dilate and start the process of bonding with your baby. The more Oxytocin you have, the better you'll feel, so keep that baby skin-to-skin as much as possible initially!

Phew, that's a lot going on in your body in less than a year, isn't it? It's no wonder that pregnancy, labour and birth can make you feel a whole lot of things, some of them good and others not great. Remember, hormones are responsible for a lot of the weird stuff you might be feeling, but if you're concerned about anything you are experiencing either physically or mentally, it's a good idea to check in with your health care provider. We hope this has helped to demystify some of the terms you might hear during your pregnancy. Good luck!


Human Chorionic Gonadotropin (HCG): The Pregnancy Hormone:

Pregnancy Hormones Explained:

Pregnancy hormones:


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