Your Complete Guide to Pregnancy Hormones

Estrogen, progesterone, and hCG are the big three, but how can these pregnancy hormones affect you?

And when do they kick in?

Finding out you’re pregnant comes with lots of thoughts and emotions.

Life is about to change!

Am I excited or terrified? Or both?

How do I need to get ready?

What can I expect next?

What about all those pregnancy hormones I’ve heard so much about?

This is all totally normal.

Plus, understanding your pregnancy hormones can help you feel more prepared during those first few weeks of pregnancy and beyond.

Let’s look at what these hormones are, why they’re important, and how they may impact your life over the next nine (ish) months.

In this article: 📝

When do pregnancy hormones start?

Pregnancy is an awe-inspiringly complex process of the human body.

It causes major shifts in the body’s endocrine system, metabolic system, and even its anatomy as the pelvic organs make room for a growing uterus.

After fertilization (sperm meets egg), a blastocyst develops as it travels to the uterine lining.

As soon as the blastocyst implants into the uterine lining (implantation), this signals to the rest of the body and hormones that it’s time to prepare.

In fact, the production of pregnancy hormones happens a few weeks before a positive pregnancy test.

The hormone progesterone is required to prepare the uterus for implantation.

Basically, it makes the uterus “sticky” enough so that an embryo can attach.

Ensuring you have adequate progesterone production during the implantation window can help you have a better chance of getting pregnant!

Proov Confirm PdG tests measure a urine marker of progesterone during the implantation window to confirm successful ovulation.

A recent clinical study showed that elevated urine markers of progesterone during the implantation window increases pregnancy rates by 8 times.*

Even after a positive pregnancy test, pregnancy hormones are active and rising!

What hormones rise first in pregnancy?

Implantation triggers the blastocyst to begin creating the pregnancy hormone human chorionic gonadotrophin (hCG).

Implantation also signals the body to increase the production of two major reproductive hormones: estrogen and progesterone.

All three are essential for a successful pregnancy, which is why a medical professional will often test the levels during your first pregnancy lab test (often called a Beta hCG).

You can expect to see an increase in these pregnancy hormones week by week, although they do plateau near the end of the first trimester.

Which hormone is only released during pregnancy?

Of the three major pregnancy hormones, hCG is the only hormone produced exclusively during pregnancy.

This special hormone is initially created by the developing embryo itself before being produced by the placenta later in development.

Pregnancy tests measure hCG, and only once it reaches a certain level will a digital test show that magic word: Pregnant.

(Although you may have trace amounts of hCG in your body, the level would not be high enough to register on an at-home pregnancy test unless pregnant.)

Some pregnancy tests are more sensitive than others and may be able to detect pregnancy sooner, like Proov Check, which can detect pregnancy up to 5 days before an expected period.

If you’re uncertain about your hCG level or at-home pregnancy test results, you can have your hCG levels tested through a blood serum lab test.

How do hormones make you feel?

You already have lots of adjustments to make in pregnancy, but are your emotions one of them?

It’s not uncommon to wonder if you’re experiencing pregnancy hormone mood swings.

You may even be asking, “Can pregnancy hormones cause anxiety?”, so let’s take a look at what to expect (from your mental health) when you’re expecting.

Studies have found that women are more vulnerable to anxiety and certain mental health disorders than men.

Those who will develop these disorders are more likely to develop during childbearing years, regardless of pregnancy state.

So, pregnancy itself does not often cause anxiety and depression.

Studies vary on whether pregnancy reduces, stabilizes, or increases these symptoms.

There have been reports that women who have struggled with anxiety or depression experience a reduction in these areas while pregnant.

Others state that pregnancy did not decrease their symptoms, but even increased them.

If you do experience dramatic changes to anxiety or depression, there are medications that are approved for use during pregnancy, as well as lifestyle decisions that can support your mental health.

It’s best to have a chat with your doctor about it.

There is help available.

What hormone causes morning sickness?

Even if research is unclear about the role pregnancy plays in mood or mental health, there’s no question about the increased possibility of morning sickness.

(Psst: we prefer the term “pregnancy nausea”, since it can strike at any time of day, not just the morning.)

Although often experienced throughout the day, the term morning sickness is used to represent the experience of nausea and/or vomiting often experienced in the first trimester of pregnancy.

So which hormone is to blame for pregnancy nausea?

Well, it’s difficult to tell.

HCG is largely considered the cause of nausea and vomiting in pregnancy, but reports show a variety of results when monitoring levels of hCG alongside reports of pregnancy nausea.

Still, hCG is said to be the most likely cause of pregnancy nausea because of the corresponding relationship between the peak of hCG levels and the peak of nausea.

Many factors other than your hCG production can influence your likelihood to experience pregnancy nausea.

If you are experiencing your first pregnancy or are pregnant with multiples, you can be more likely to experience pregnancy nausea.

And pregnant people of African, Native American, or most Asian populations are less likely to experience pregnancy nausea.

If you tend to experience motion sickness, or felt nauseous while on hormonal contraception, you’re also more likely to experience pregnancy nausea.

If you fit into several of these categories, you may experience this nausea, but there’s good news — morning sickness often subsides near the end of the first trimester.

When is the pregnancy hormone highest?

The body produces a myriad of hormones in response to pregnancy.

We mentioned the three major pregnancy hormones (estrogen, progesterone, and hCG), but other hormones increase during this time, as well (testosterone and prolactin, to name a few).

While these are all important for the developing pregnancy, hCG is most often measured as a sign of a pregnancy’s healthy progression.

This pregnancy hormone is highest between weeks 8 to 10 of pregnancy.

After that point, it plateaus and remains at a lower level throughout the rest of the pregnancy.

Pregnancy hormones have a major influence on your life and pregnancy.

While they are critical to the development of a healthy pregnancy, there’s not much that can be done to influence pregnancy hormones, like hCG.

Take this time to support yourself, invest in your mental health, and talk with your doctor about any concerns you may have.

And if you want to talk to other mamas who have been there, there’s a whole community on Peanut.

(*Amy Beckley, Joshua Klein, John Park, Aimee Eyvazzadeh, Gary Levy, Alexandra Koudele. The predictive value of urinary progesterone metabolite PdG testing in pregnancy outcomes. Obstetrics and Gynecology Research 5 (2022): 194-198.)