• Sarah Maria

Pregnancy hormones and their challenges

What hormones are there? How do they change during pregnancy? And what do they cause?

During the normal cycle of a woman, the hormones change constantly to either let the new egg grow or to start the menstruation process and therefore end the cycle. There are far more functions and daily changes in our bodies caused by hormones than the female reproductive system shows monthly. And because nearly all our daily functions are influenced or even triggered by hormones, they also play a big role during pregnancy. They may come with big advantages and pros, but also with lots of challenges.

So first of all, the same hormones that make the uterus bleed keep the pregnancy alive by protecting it: the oestrogens and the progesterone.


Oestrogens are a group of three female reproductive hormones: the oestrone, the oestriol and the oestradiol. Oestradiol is the most dominant one and plays a big role in pregnancy. They are produced in the ovaries and later in the placenta.

The oestrogens build-up the uterine mucosa to make sure it is ready for an egg to grow. As soon as the fertilized egg starts to attach to the uterine wall, the oestrogens make sure, that the uterus nurtures the fetus until the pregnancy is over. It is responsible for the save surroundings for the baby to grow. Oestrogen levels in pregnant women do fluctuate during the whole pregnancy, so don’t get them checked too often to avoid panic. The body tries to balance it throughout the whole pregnancy.

It is produced right at the offspring of pregnancy from the corpus luteum until the placenta is ready to take over the production of hormones.

Moreover Oestrogens

  • help the uterus to grow space for the baby

  • support the development of its organs, like lungs, liver and kidneys

  • support the maternal breasts growth for lactation and prepares its glands

  • stabilize the immune system of the mother

  • increase blood coagulation

Not only does the placenta produce the hormones, the oestrogens then make sure the placenta fully functions and stays healthy. On top of all this, they ensure that the uterus is ready to get stimulated by oxytocin, the hormone for contractions, at the very and of pregnancy.

The downside: Oestrogens may also cause lots of nausea at the beginning, and by making the ligaments in your lower back and pelvis softer, increases back pain and pressure on your pelvis.

The group of oestrogens also makes sure that enough progesterone is produced throughout these 9 months, which brings us to our next ingenious hormone.

The progesterone:

The Progesterone ist very important for the survival of the fetus, therefore it is often described as the pregnancy-obtaining-hormone. It is, as well as the oestrogens, produced by the corpus luteum until the placenta takes over. Progesterone

  • increases blood flow

  • makes the blood vessels of your uterus lining nutritious and voluminous to nourish the baby from a very early stage on

  • supports the attachment of the placenta and implementation of the embryo

  • later the ensures correct fetal development.

Progesterone plays a key role in preventing the uterus from contracting and giving birth too early. It keeps the baby safe inside the womb until it is ready and smoothes the uterine muscles. Besides contractions Progesterone also prevents lactation until after birth and helps with the growth of breast tissue, alongside oestrogens. At the same time as progesterone relaxes the uterine muscles, it strengthens the pelvic floor so it does not “hang loose” and prevents the baby from dropping to low and therefore being born too early.

Already noticed the beautiful pregnancy glow up: shiny hair, beautiful nails and great skin? thank you progesterone!

Until the mothers body fully adapted to the hormone changes happening, mood swings can be normal, and of course the famous morning sickness. The rapid increase in all pregnancy hormones most likely trigger nausea, usually gone by week 12-18.

Many other hormones including relaxin, human chorionic gonadotrophin, prolactin and oxytocin are important. If you are interested to read more about them, leave a comment or make sure to subscribe to the blog to be updated for the next post!

Stay safe, stay healthy and remember:

it’s not pain, but power!

your midwife Sarah

Photo by Ghaith Harstany on Unsplash


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