Hormonal changes during pregnancy

During your pregnancy, you will experience a rise in your existing hormone levels and the arrival of new ones, bringing changes that you may not be able to explain. To understand what’s going on inside your remarkable body, we’ll discuss some of the main hormonal symptoms of pregnancy and the changes these hormones can bring.

What hormones increase during pregnancy?

Several hormones support your adapting pregnant body and growing baby. Here are the main pregnancy hormones at work and the changes each one brings.

HCG hormone in pregnancy

Produced by what ultimately becomes the placenta, hCG (Human Chorionic Gonadotropin) helps support early pregnancy in several ways.

What does hCG do during pregnancy?

• A pregnancy has begun
• To support the lining of the uterus
• To stop the ovaries from maturing an egg each month

HCG levels usually peak towards the end of the first trimester, before gradually settling. In the first 10 weeks, hCG levels usually rise quickly and may roughly double every 2 to 3 days. HCG can be detected in your urine, which is what many over-the-counter pregnancy tests look for.

Progesterone during pregnancy

In early pregnancy, progesterone is produced by the corpus luteum (a nodule on the ovary). The corpus luteum makes progesterone until about 10 weeks, when it’s taken over by the new placenta. Progesterone is important throughout pregnancy, and levels continue to change as the pregnancy progresses.

What does progesterone do during pregnancy?

• Helps keep the muscles of the uterus relaxed
• Helps your immune system adapt during pregnancy
• Develops your breasts, ready for milk

You may notice your breasts becoming fuller, tender and itchy (skin stretching) and veins becoming more noticeable. To help look after them, you may find it helpful to wear a supportive, non-wired bra and apply some moisturiser to ease the stretching skin.

Oestrogen during pregnancy

Like progesterone, oestrogen is supported by the corpus luteum until the placenta takes over.

What does oestrogen do during pregnancy?

• Increases blood flow
• Plays a role in the development of the uterine lining
• Prepares the uterus to respond to oxytocin, the bonding hormone involved in labour contractions
• Supports your baby’s growth and development
• Enlarges your milk ducts, ready for milk production

These changes continue as pregnancy progresses.

Relaxin hormones in pregnancy

Relaxin is the hormone that loosens the ligaments of your pelvic bones. This hormone increases significantly in pregnant women.

What does relaxin do during pregnancy?

Relaxin is very important because it prepares your body for giving birth. It also helps blood vessels relax as blood volume increases during pregnancy.

When to seek further support

Early hormonal changes in pregnancy are perfectly normal, even when they bring symptoms you weren’t expecting. Many changes settle or shift as pregnancy progresses, but speak to your midwife, GP or healthcare professional if anything worries you.

For more guidance and tips, explore the Capricare® Parent Support Hub.