Pregnancy hormones are responsible for many of the changes to your body and emotions. This article explains which hormones are doing what whilst you are pregnant.

hCG or human Chorionic Gonadotropin

hCG helps in the production of oestrogen and progesterone within the ovary. It is released very early in pregnancy. This is the hormone which pregnancy tests look for. This pregnancy hormone disappears once the placenta is mature enough to start producing the oestrogen and progesterone your body needs.


Oestrogen is produced throughout your pregnancy. It helps to regulate levels of progesterone, prepares the womb for the baby and, prepares the breasts for feeding. It can be the reason your breasts get bigger and become tender.


Progesterone prevents the womb from spontaneously aborting the foetus by building up the womb lining so that it can support the placenta, and by preventing the natural movement and contractions of the womb. It is responsible for the loss of interest in sex during pregnancy (this doesn’t happen to everyone).

It relaxes your joints and muscles and allows the pelvis to open up. It also slows down the intestinal tract and causes acid reflux and constipation to become common complaints during pregnancy. It is also responsible for increasing your temperature, making you feel warm and sometimes experience night sweats.

NB: Oestrogen and Progesterone levels fall dramatically after birth to almost pre-menopausal levels. This can be responsible for you feeling low or anxious and having hot sweats and vaginal dryness. They return to normal levels when your normal menstrual cycle returns.


Prolactin is produced by the pituitary gland. It is responsible for the increase in cells which produce milk within the breasts. Immediately after birth it kick starts the initial production of milk. It also helps a breastfeeding mum from falling pregnant again, although this is not a reliable form of contraception!!


Relaxin is released from the placenta, the amniotic sac and the lining of the womb. Relaxin levels are at their highest in the first trimester of pregnancy. The hormone encourages the implantation of the developing foetus into the wall of the womb, and the growth of the placenta. It inhibits contractions to prevent premature labour.

Towards the end of pregnancy, relaxin helps your waters to break, and the softening and opening of the cervix and vagina to help the process of labour. Relaxin is responsible for relaxing the joints and ligaments in the pelvis. It affects other parts of the body too so you might feel more clumsy or prone to falls. You may also feel pain in your lower back and wrists.


Oxytocin triggers caring behaviour and is known as the ‘bonding hormone’, which helps you to feel close to your baby. It is also the hormone which stimulates contractions of the womb during labour – a synthetic version is used to start or speed up labour, if needed.

If you breastfeed your baby, oxytocin is responsible for the contraction-type feelings you may experience, which help reduce the womb to pre-pregnancy size.

Find out more: Oxytocin: The love hormone.


Prostaglandins are tissue hormones that seem to play a role in getting labour started. Synthetic prostaglandins are used to induce labour.

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The information contained above is provided for information purposes only. The contents of this article are not intended to amount to advice, and you should not rely on any of the contents of this article. Professional advice should be obtained before taking or refraining from taking any action as a result of the contents of this article. New Life Classes disclaims all liability and responsibility arising from any reliance placed on any of the contents of this article.