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Pregnancy hormones

If your body and your mind feel all over the place right now, the main culprit is your pregnancy hormones. Here’s what you need to know.

If you’ve been wondering why pregnancy has sent you into daily crying fits or rages, then we have one word for you: hormones. Yet as well as affecting your mood, these super-powerful hormones can also affect:

  • growth and development
  • metabolism
  • sexual function
  • reproduction.

(MedlinePlus, 2016)

Yep, when you’re pregnant, hormones play a massive role (Kumar and Magon, 2012). They can influence things like the way you now sob at an episode of EastEnders. They also explain why everyone says you are ‘glowing’ and why your nails have grown properly for the first time since you were eleven.

They also help your growing baby develop and make a difference physically, with certain hormones relaxing your ligaments ready for labour. That might mean you find yourself getting more injuries or niggles in the body when you exercise while you’re pregnant too (Healthline, 2017).

Hormones may also have you leaping on your partner at certain points in your pregnancy, and horrified by the idea of sex at others.

Progesterone, oestrogen and other hormones in pregnancy

The most important hormones at play when you’re pregnant are as follows.


Oestrogen is produced in early pregnancy to support your baby until the placenta takes over. Oestrogen helps the development of your baby’s organs and the correct function of the placenta. Yet it may also cause nausea and make ligaments softer, putting pressure on your lower back and pelvis (NHS, 2018).

Later in pregnancy, oestrogen helps to prepare your body for breastfeeding (if you choose to do so). It also enables your uterus to respond to oxytocin in labour (Society for Endocrinology, 2018).


Progesterone is produced in early pregnancy to support your baby until the placenta takes over. Progesterone causes an increase in blood flow to the womb. It might also be the one responsible for that pesky heartburn as well as vomiting, reflux, gas and constipation (Society for Endocrinology, 2018).

Later on it can help with your baby’s development. It’ll prevent you from producing milk until your baby’s born and will strengthen your pelvic floor muscles ready for labour (Society for Endocrinology, 2018).


Oxytocin eases the pain during labour, and encourages the cervix to open as well as helping with your lochia (bleeding after birth). Oxytocin also plays a major role in milk production and bonding (Society for Endocrinology, 2018).


Similar to oxytocin, prolactin helps with bonding (Society for Endocrinology, 2018).


This is the hormone that makes your ligaments softer and means you need to adjust certain types of exercise so you don’t get an injury. Relaxin helps in labour, as it softens and lengthens the cervix as well as your pelvic area (Society for Endocrinology, 2018).

Human chorionic gonadotropin (HCG)

HCG is released into your bloodstream when you get pregnant to support you and your baby. It’s often an indicator of pregnancy in over-the-counter tests as well (Society for Endocrinology, 2018).

Human placental lactogen (hPL)

The hormone hPL helps your baby to get the nutrients they need while you’re pregnant (Society for Endocrinology, 2018).


Prostaglandins help to get the cervix ready for labour (Society for Endocrinology, 2018).

Hormones and emotions during pregnancy

While it can be a happy time in many ways, you’re likely to feel emotionally vulnerable and down at times during your pregnancy. No matter how excited you are that you’re having a baby.

If you think you’re feeling down or anxious a lot, speak to your GP, midwife and someone close to you (Northamptonshire Healthcare NHS Foundation Trust 2015). Feeling this way during pregnancy can also increase the chances of postnatal depression later down the line, so it’s good to flag it now.

This page was last reviewed in July 2018.

Further information 

Our support line offers practical and emotional support with feeding your baby and general enquiries for parents, members and volunteers: 0300 330 0700.

We also offer antenatal courses which are a great way to find out more about birth, labour and life with a new baby.

Healthline. (2017) What bodily changes can you expect during pregnancy? Available from: [Accessed 11th July 2018]

Kumar P, Magon N. (2012) Hormones in pregnancy. Niger Med J. 53(4):179-183. Available from: [Accessed 11th July 2018]

MedlinePlus. (2016) Hormones. Available from: [Accessed 11th July 2018]

NHS Choices. (2018) Back pain in pregnancy. Available from: [Accessed 11th July 2018]

NHS Inform. (2017) Exercises during pregnancy. Available from: [Accessed 11th July 2018]

Northamptonshire Healthcare NHS Foundation Trust. (2015) Emotional changes during pregnancy and following childbirth. Available from: [Accessed 11th July 2018]

Society for Endocrinology. (2018) You and your hormones. Hormones of pregnancy and labour. Available from: [Accessed 11th July 2018]

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