Pregnancy Hormones: How your Body Changes Throughout the Process

Pregnancy Hormones: How your Body Changes Throughout the Process

There is no doubt that it is both exciting and terrifying when you find out about your pregnancy for the first time. It is so exciting because bringing a baby into this world is great news but it can understandably be nerve-racking for expecting mothers to watch their bodies go through so much change in such a short amount of time. 

The more knowledge you have about understanding pregnancy hormones and how your body responds to these changes the less nervous you’ll be. Let’s talk about these changes and what you can expect with pregnancy hormones. 

What are the main pregnancy hormones?

What are the main pregnancy hormones?

There are many different hormones that you can blame for a lot of things during your pregnancy. When you understand that your “glow” comes from this and your mood swing is to blame for that, you actually can take comfort in knowing what’s going on. 

Here is a comprehensive list of the main hormones and their functions during pregnancy. 


Estrogen has a very important role as one of the main hormones. It deals with sexual development that contributes to the growth of the breasts as well as plays a massive role in your menstrual cycle. During pregnancy, it helps kick the party off with progesterone. It helps the Uterus grow as well as help breastfeeds by producing the tissue for milk. 


Progesterone mainly sits in your ovaries and has the primary function of regulating your menstrual cycle once you have gone through your period. Progesterone in pregnancy helps the uterine lining become receptive to the egg so it can implant itself. 

Follicle Stimulating Hormone

FSH has the main function of creating estrogens and eggs. It comes from your pituitary gland and during pregnancy contributes by making pregnancy possible. Without the development of eggs, there would be nothing for sperm to combine with. 


Relaxin is a hormone that is directly related to the reproductive system. The reason being is that Relaxin helps by getting the uterine wall ready for pregnancy. Relaxin sounds exactly as it functions. It helps soften the uterus and the bones and muscles in the body when it is time to conceive. 


Oxytocin is very important when it comes to delivering your baby. It is produced by the pituitary gland also and is what contracts your muscles when you start to go into labor. This is what pushes the baby along. Sometimes when women have weak contractions then doctors give them more oxytocin. 

Placental Growth Factor

This hormone works so that the baby is getting enough blood flow. For this to happen your blood vessels need to pump more blood and become stronger. Thanks to the Placental Growth Factor they can do this function keeping both you and the baby healthy. 

Human Placental Lactogen

This is another hormone that helps prepare your body to feed the baby through breastfeeding and producing milk. It works with Prolactin which you can see below. 


This hormone is what is responsible for helping you produce milk or lactate through the breasts for the baby. As you become pregnant and your breasts enlarge the prolactin revs up in your body. 

Human Chorionic Gonadotropin 

You may have heard some of the other hormones on the list and am now confused as to what this one possibly is. Human Chorionic Gonadotropin is responsible for letting you know you are pregnant. It is what a pregnancy test tests for and when the levels rise it indicates you’re pregnant. 

Luteinizing Hormone

The LH works with FSH to raise levels of hormones before ovulation. This actual hormone is responsible for triggering the release of the egg during your menstrual cycle. This happens after FSH produces the eggs. 

Hormonal changes during pregnancy

Hormonal changes during pregnancy

Let’s break pregnancy into the three trimesters and talk specifically about the rise and drop and even the introduction of hormones during these different times. This helps us better understand why something happens when it happens. 

First Trimester

In the first trimester, your body experiences a whole lot of different feelings that can be quite uncomfortable at times. You can expect during the trimester the following to happen.

  • Estrogen and progesterone levels will rise dramatically. Nausea is one of the common side-effects that women report when estrogen levels rise so quickly in the first trimester. Progesterone is the culprit for constipation and moodiness. 
  • HCG, the hormone that lets you know you're pregnant, is now introduced. 
  • TSH or Thyroid-Stimulating Hormone can be stimulated from the HCG to work harder and make sure things are running smoothly. 

Second Trimester

Now we can look to some other hormones that start coming into play in the second trimester of a woman’s pregnancy. 

  • While estrogen and progesterone continue to rise you actually may start to feel bad because it is at less rapid levels. 
  • HPL starts to kick in as the fetus begins to grow rapidly during this stage. 

Third Trimester

Hitting the home stretch you may start to feel a lot of back pain as your baby continues to grow. A few more hormones will start kicking just like the baby to help you get through these final weeks. 

  • Prolactin increases rapidly during the third trimester as you get ready to deliver so you can be ready to breastfeed. 
  • Oxytocin will become present when you start having contractions and go into labor since that is what is responsible for. 

Main pregnancy hormones

While we have a long list of pregnancy hormones we don’t exactly need to go over where each comes into play. The main ones that every woman needs to focus on are estrogen and progesterone as these play a major role at the beginning of the pregnancy, labor, and even after pregnancy. 

You may notice that your hair has become thicker and you have more of it. This in part is due to estrogen and progesterone. After you have the baby you will experience a rapid drop in both of these hormones which calls all that extra hair to shed. This is one way of being able to tell your hormones are rapidly changing. 

Progesterone and estrogen can also be responsible for the “baby blues” because of the drop that occurs so quickly. Because they have the most impact these are the main pregnancy hormones. 

Body changes due to pregnancy hormones

Body changes due to pregnancy hormones

Our body during pregnancy goes through many different changes from appearance to mood. Let’s talk about some of the physical changes that occur because of hormones and what you can expect. 

Weight Gain

One of the most obvious physical changes that will happen is your body will gain a lot of weight. This is because of the baby’s development but also because of fluid retention. This leads to some swelling of the joints because of the extra weight women have to bear. The best thing you can do is rest and get off your feet as well as take walks to loosen up muscles that may tighten while laying around. 

Breast Enlargement 

A woman’s breast will continue to grow and feel swollen as the hormones like Prolactin and others produce tissue to prepare the mother for breastfeeding. Around the second trimester, the mother can expect small secretions of yellowish fluid from her breasts as they undergo these changes. This is normal as there is a lot of breastmilk pumping and getting ready to come out for the baby. 

The Desirables

There are certain physical changes that women do desire. The glow is something that everyone talks about and this occurs along with getting thicker more full hair and strong nails. This is because of the estrogen levels rising and unfortunately, when they drop after pregnancy likely you will lease these desirable physical features. Some women complain that their hair is falling out but you are just shedding the new hair you grew during pregnancy. 

Pregnancy Hormones FAQs

Even though that was likely a lot to suggest you may still have some pregnancy hormones questions. Because everyone’s journey is both similar and incredibly unique it can be tempting to have wonders and questions about everything. Here are the most Frequently Asked Questions associated with pregnancy hormones. 

Is it normal to feel increased sexual desires during pregnancy? 

It is incredibly normal to feel an increased sexual desire because of your libido increasing. This is also due to hormones. This is most common during the first trimester and the second trimester. Many doctors will say that intercourse is a great way to deal with your hormones by releasing stress and connecting with yourself. 

It is also possible that you may feel sexually disconnected from yourself. Because of the hormones increasing rapidly and causing nausea and tiredness, sex can be the last thing on your mind. One of the more common situations is that women flip flop between feeling a desire to have intercourse and wanting nothing to do with it because their bodies and emotions are flipping. 

Is it normal to feel no noticeable changes emotionally?

Some women feel like from the second they conceive they know because they feel emotional, sick, tired, and all over the place. Other women will say that the pregnancy is a breeze and feel nothing but their bodies physically changing. 

Since everyone is different it is tough to say what is normal and what is not. I think the only point of concern is that if you notice not a lot of physical changes then talk to your doctor. Some women show late so this is also not something to panic over. 

What hormones continue to play a role post-pregnancy?

Besides estrogen and progesterone play a big role in the baby blues due to the drop, Prolactin and Oxytocin continue to uptick. Prolactin will help continue to produce breast milk to feed your baby. Oxytocin has a big uptick because it helps the mother prevent excessive bleeding and keeps her safe after delivering.

The baby blues are worth noting because 80% of new mothers experience this. Just like you may experience nausea due to a rapid increase in estrogen and progesterone, you will also experience a rapid drop the second you deliver. This can cause a mood drop that increases anxiety, depression, among other irritable emotions. Combined with tiredness and any difficulty in sleeping and this can further worsen baby blues feelings. This is completely normal.  


Hormones are to blame for every happy and not-so-happy feeling you get both emotionally and physically. While there is a long list of hormones that play a role from pre-pregnancy to delivery and afterward, the two main ones that any pregnant mother needs to focus on are Estrogen and Progesterone. They affect several things from nausea to hair growth to baby blues. 

When we understand how each of the hormones plays off each other throughout the first, second, and third trimester we can take some comfort in the physical changes we notice. Weight gain will be the most noticeable physical change as the baby grows and the body starts to swell. 

Realizing that every woman's pregnancy journey is different from the next woman’s is the most important thing. While some women have higher sex drives some women will feel awful about their bodies. All are acceptable and a part of the process!