Hormones during pregnancy part 2

This series of articles continues to look at the effects of a finely tuned orchestration of hormones during pregnancy.

Pregnancy Hormone - Human Placental Lactogen

Last week, our holistic therapy and midwifery expert, Amanda Gwynne, explored the roles of Human Chorionic Gonadotrophin (HCG) and progesterone during pregnancy. This week she examines Oestrogens, Human Chorionic Somatomammotrophin and Melanocyte Stimulating Hormone.


  • The main source of oestrogens in pregnancy is the placenta but they are also produced by the maternal and fetal adrenal glands
  • The production of oestrogen is complex and requires a close interaction between both placenta and fetus for synthesis to occur
  • Oestrogen regulates progesterone, protecting your pregnancy
  • Maintains both uterine blood flow and the endometrium (lining of your uterus) during your pregnancy
  • Increases blood flow to mucous membranes, hence the congestion of sinuses and a stuffy nose!
  • Encourages the growth of milk ducts within the breast, and enhances the effects of prolactin which stimulates milk production
  • Oestrogen is responsible for the growth and maturation of fetal organs such as the lungs, kidneys, and liver, as well as reproductive organs
  • It also regulates bone density as your baby develops and grows
  • Finally, oestrogen protects female babies in-utero from the effects of male hormones

Human Chorionic Somatomammotrophin (HCS)

  • Commonly called Human Placental Lactogen (HPL) is produced by the syncytiotrophoblast
  • The secretion of HPL is complementary to that of HCG, and as the level of the latter falls HPL increases
  • It appears to alter your metabolism so that your baby thrives and grows, as you use more fatty acids leaving more glucose for your baby to thrive
  • In conjunction with oestrogen and cortisol, HPL can block the action of insulin from approximately 20-24 weeks of pregnancy elevating blood sugar levels, which may be a precursor for gestational diabetes
  • This hormone helper initiates changes in preparation for breast feeding activating the secretion of colostrum

Melanocyte Stimulating Hormone

  • A combination of oestrogen, progesterone and melanocyte stimulating hormone can cause skin discolouration (skin pigmentation) affecting your nipples, areola and linea nigra (the line that runs down from your abdomen to your pubic bone). See image below of linea nigra.
  • Causes the tanned look of the skin on your face commonly known as ‘chloasma’ or mask of pregnancy
  • May increase your susceptibility to sunlight, so take extra care when out and about in the sun
Linea nigra stimulated by Melanocyte

Picture of Linea Nigra

It never ceases to amaze me how incredible our bodies are, especially during the miracle of pregnancy and childbirth. Join me next time as we continue to explore our symphony of hormones.

Photography: Daniel Lobo @Flickr, Wikimedia Commons

Comments for 'Hormones during pregnancy part 2'

Comments are closed.

This entry was posted in Pregnancy, Your Pregnancy Health and tagged , , , , . Bookmark the permalink.