Hormones and pregnancy

Me, pregnant

Pregnancy is a period of time regulated in an extreme strict way by several hormones.

I will talk about the 5+1 most important hormones typical of pregnancy.

Hormones involved in pregnancy

1 – Human chorionic gonadotropin (hCG)

It is produced by the placenta after implantation. It is the hormone detected by pregnancy tests. It seems to be the cause of the feeling of “sickness”, nausea and sensitivity to certain odors typical of the beginning of pregnancy.

2 – Progesterone

It helps establish the placenta. It is produced by the corpus luteum until the 10th week of gestation and later by the placenta itself. It stimulates the blood vessels and the breast growth and inhibits the contraction of the uterus. Progesterone inhibits the maternal immunologic system, preventing the rejection of the fetus. Moreover, this hormone strengthens the pelvic wall in preparation for labour. It inhibits lactation during pregnancy. It is responsible also for the typical digestive problems of pregnant women and the mood swings

3 – Estrogen

It helps the uterus grow and promotes the increase of blood flow. Estrogen stimulates the growth and correct functioning of the placenta. This hormone helps the fetal organs development and stimulates the breast growth, making it achy and tender. It is also responsible for stuffy nose and the constant need to pee, which pregnant women know too well.

4 – Prolactin

It is needed to produce milk, it contributes the enlargement of the mammary glands. Its level rise starting from the 20th week.

5 – Relaxin

The main scope of relaxin is to relax different part of out body. In particular, it inhibits uterus contraction, it relaxes blood vessels and joints and lengthens the cervix during birth.

Bonus hormone – Oxytocin

It is produced only at the end of pregnancy. Oxytocin stimulates the contraction of the uterus, which is the starting signal for labour.


Kumar and Magon, “Hormones in pregnancy”, (2012), 10.4103/0300-1652.107549


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