Pregnancy Hormones You Should Know About?

There are many important hormones produced by your placenta throughout pregnancy. They play differing important roles in the health and development of your baby. Often they have various symptoms and side effects. These are sometimes referred to as the minor complaints of pregnancy. But, sometimes they can be not so minor, for example, morning sickness! Relief is often available with safe treatment from some of these annoying symptoms. Fortunately, the symptoms disappear following the birth of your baby.

A hormone is simply a protein produced by one cell type that enters the bloodstream and affects another cell type’s function and metabolism. Here are a few hormones worth knowing about.

Human Chorionic Gonadotrophin (HCG).

This is the hormone that a woman tests for at home when she thinks she may be pregnant. This is done with a simple urine test kit bought from the chemist. When a woman is late for her period due to pregnancy, the test will be positive. Modern urine test kits are extremely sensitive.

This amounted HCG can be accurately measured in the bloodstream. Doctors often test for this hormone twice, testing at least 48 hours apart when there are concerns in very early pregnancy (less than 6-7 weeks). Normally if everything is going well, the level doubles every 48 hours approximately.

HCG rises steeply until around 12 weeks, and begins to fall at about 15 weeks. It possibly plays a role in morning sickness.


This sex steroid hormone is produced initially by the ovary until around 10 weeks. After that, the placental tissue takes over this role for the remainder of pregnancy. Progesterone, as its name suggests, is critical to the development and maintenance of pregnancy. It maintains the lining of the uterus in a healthy state, and critically prevents the uterus from contracting, allowing the pregnancy to gradually expand. This is achieved by relaxing the smooth muscle fibres in the muscular wall of the uterus. Unfortunately,  progesterone relaxes smooth muscle fibres everywhere else in the body.

Thus the muscles fibres lining the woman’s gut, for example, are relaxed. This leads to annoying symptoms like heartburn ( acid reflux), indigestion and constipation. Safe treatment is available for these symptoms. Episodes of breathlessness are probably due to progesterone as well.


This protein hormone is produced by the placenta. Its function is to soften the tough fibrous tissue in the pelvic joints and pelvic floor. This allows for a little widening of the birth canal to help the woman give birth.  Because relaxin is released into the bloodstream especially in the later stages of pregnancy it softens connective tissue (ligaments ) everywhere. This contributes to many women noticing low backache and annoying hip pain for example.

Oestrogen (Oestradiol).

The most well known female hormone is produced in large and increasing amounts throughout pregnancy. It plays an important role in interacting with progesterone to maintain pregnancy. It is believed that oestrogen helps with foetal organ system maturation. Oestrogen also promotes milk duct development and thus breast enlargement in pregnancy. With HCG, oestrogen contributes to nausea in susceptible women. Effective, safe treatment for nausea and vomiting is available. Pregnant women usually notice their body feels warmer, a bonus in winter but not so in the summertime. This is another oestrogen effect which is normal.

To make an appointment to discuss your pregnancy, please call the rooms.

Author: Dr Peter England, Obstetrician and Gynaecologist.
Read more about Dr Peter England

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