Pregnancy hormones

Changes in hormones during pregnancy can cause physical changes and mood swings.

This article covers the following topics regarding pregnancy hormones:

Conception and hormones in early pregnancy
Hormones and emotions during pregnancy

Pelvic floor

Hormones later in pregnancy

Further information

Hormones are chemicals that circulate in the blood, and they have powerful and varied functions. Different hormones regulate body functions and carry messages from one part of the body to another. Hormones recognise emotional triggers; they can cause you to cry when you are sad and to react to fear or danger with the ‘fight or flight’ response.

Hormones (during pregnancy) are there to help regulate the many changes taking place to enable your baby to be born safely. Understanding what the hormones are doing may help you understand the changes in your body, and help decide what’s normal and what may not be. 

Some of the most significant hormones in pregnancy are:

  • oestrogen
  • progesterone
  • oxytocin
  • endorphins
  • prolactin

Hormones also play an important part in the process of birth.

Conception and hormones in early pregnancy

During early pregnancy, the female hormones (which include oestrogen and progesterone) have helped release an egg from your ovary and implant it in the lining of your uterus.

You will have higher levels of both of these hormones as they help to create the necessary increase in blood supply, especially to the uterus and your breasts. Progesterone and another hormone, relaxin, also enable the muscles of the uterus to relax to make room for the growing baby. The change may affect other muscles in the body, which can sometimes make your joints and your back ache and affect your pelvic floor

The relaxed muscles and tissues in your digestive system may also contribute to experiences such as heartburnnausea, and constipation.

Hormones and emotions during pregnancy

The altered hormone levels can affect how you feel. You may at times feel low or tearful or be easily irritated. For a while, you may experience mood swings during pregnancy or feel that your emotions are out of control. Often these symptoms ease after the first three months of being pregnant. The feelings of loss of control are also linked to the changes in your body, and it is a good idea to remind yourself that they are all designed to provide a healthy environment for your growing baby and to help you give birth without problems.

Pelvic floor

The pelvic girdle is the system of bones that surround and protect your uterus and other organs in this area. Its base, the pelvic floor, is a network of muscles and ligaments which support the organs, including the expanding uterus with the baby inside. The softening of the tissue caused by the relaxin hormone means these ligaments are more elastic to help when the baby is born, but the muscles need to be kept strong with pelvic floor exercises

Hormones later in pregnancy

For many women – though not all – the middle months see a return of energy levels and an end to nausea and some other problems of the early weeks. You may find that the actions of hormones now make your skin glow and your hair shine – this is the ‘blooming’ stage that others often notice. Your shape may become more visible and you may feel able to be more public about the fact that you are pregnant. The risk of miscarriage reduces as you leave the first trimester, and many women begin to feel more confident in their pregnancy.

Further information 

NCT's helpline offers practical and emotional support with all aspects of being pregnant, birth and early parenthood: 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.

NHS choices offers information on hormones in breastfeeding.

NHS choices has information on postnatal depression.