Hormones during pregnancy and childbirth part 4

In this final part of Hormones of Pregnancy series, our pregnancy and birth expert, Amanda Gwynne, focuses on the remaining hormones of labour, birth and breastfeeding.

Pregnancy Hormones - Prolactin

Childbirth involves peak levels of oxytocin and prolactin. Add to these beta-endorphins our body’s natural analgesia, and our ‘fight or flight’ hormones adrenaline and noradrenaline, and we have a potent cocktail.


  • Beta-endorphins are stress hormones produced in the pituitry gland and inhibits the perception of pain
  • High levels are present during lovemaking, pregnancy, birth and breastfeeding
  • A naturally occurring opiate with analgesic properties similar to synthetic opiates such as pethidine
  • Suppresses the immune system which may be an important factor during early pregnancy aiding acceptance by our body of our developing baby
  • It induces feelings of pleasure, euphoria and dependency
  • Very high levels during labour, help women to transcend pain and reach an altered state of awereness or ‘zone out’

Fight or Flight Response Hormones

  • Hormones adrenaline and noradrenaline comprise our fight or flight response to stress or danger
  • Collectively they are known as catecholamines (CA)
  • They are secreted by the adrenal glands in response to stressors, whereby they activate the sympathetic nervous sytem for fight or flight
  • In the first stage of labour high levels of catecholamines inhibit oxytocin production which in turn slows or stalls labour
  • They also reduce blood flow to the uterus, placenta and indirectly to the baby as the blood is redirected to major muscles groups
  • Therefore, high levels of these hormones may prolong labour and lead to fetal distress
  • Recent research has indicated that a sudden increase in catecholamines at the end of labour may be beneficial, activating the ‘fetal ejection reflex’ and a surge of strong contractions facilitating an easy and quick birth
  • Post delivery effects include a rapid drop in levels and subsequent side effects of feeling cold and shivery, when it is important to remain warm
  • Baby also experiences high catecholamine levels at birth, which ensures that he/she is alert and responsive, important for bonding and breastfeeding


  • Commonly known as the ‘mothering’ hormone prolactin is produced in the pituitry gland
  • Increased levels during pregnancy promote development and enlargement of the mammary glands of the breasts
  • Falling levels of progesterone stimulate milk production in conjunction with your baby’s sucking stimulation
  • Contributes to the surfactant synthesis of your baby’s lungs which help them to mature
  • Prolactin may make you feel more maternal
  • High levels are found in fathers closely involved with their baby promoting bonding and reducing testosterone levels and libido, but not sexual function!
  • Prolactin is produced during sleep and levels are highest at night, hence the importance of night feeding for lactation
  • Baby also produces prolactin in pregnancy and early research indicates it may play a role in maturation of baby’s brain/hormone system

For more information on the hormones of pregnancy and how they effect your body see;

Human Chorionic Gonadotrophin (HCG) and Progesterone in pregnancy hormones part 1
Oestrogens, HCS and Melanocyte Stimulating Hormone in pregnancy hormones part 2
Relaxin and oxytocin in pregnancy hormones part 3

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