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Progesterone and Pregnancy: How Does One Affect the Other?

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As we begin fertility testing and start examining our infertility treatment options, we’re likely to confront a kaleidoscope of new jargon, acronyms, and subject matters. Information on how progesterone and pregnancy go together is sure to be one of these things.   

It’s funny to think back to my first experiences with infertility.

While I understood my irregular periods weren’t favorable for conceiving children, I wasn’t aware that other topics, like low progesterone in pregnancy, could also be troublesome.

The further we fell down the “what is infertility” rabbit hole, the more we realized this hormone could make or break our ability to get pregnant. 

Whether you’re dealing with secondary infertility, recurrent miscarriage, or PCOS-related infertility, progesterone levels are almost certain to play a role in your process. 

But what is this unknown substance, and how could it be the determining factor in your quest to become a parent? Lucky for you, we’ve talked to the experts and have all the information you need to know. 

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What is Progesterone?

Warning: Scientific jargon ahead, but don’t let that deter you!

Progesterone is a steroid hormone released by the corpus luteum. The corpus luteum is a temporary endocrine gland produced by our bodies during the second half of our menstrual cycles – the period after ovulation. 

Phew – that was a mouth full!

I know what you’re probably thinking, “All of that hormonal mumbo jumbo sounds nice but still doesn’t explain to me what progesterone and pregnancy have to do with each other!”

To put it plainly, progesterone is the substance in our bodies that helps prepare the endometrial lining for possible pregnancies.

Progesterone levels will rise before eggs release during ovulation to accommodate developing embryos (should they occur.)

What is Progesterone’s Function in Pregnancy?

As we prepare for pregnancy, it’s beneficial to understand how the reproductive system works. This knowledge helps us understand what it takes for conception to occur. 


When it comes to progesterone during pregnancy, the presence of this incredible hormone can be the difference between a viable and non-viable pregnancy.

Progesterone’s primary function in the menstrual cycle is to make things “sticky” by thickening their endometrium. This allows the uterus to accept better-developing embryos and assist with the implantation process.

After implantation occurs, however, the body will continue producing progesterone to help with other aspects of pregnancy, such as:

  • High progesterone levels throughout pregnancy will prevent ovulation
  • Progesterone and breast milk production go hand-in-hand. 
  • Progesterone levels in early pregnancy prevent muscle contractions that can cause a the body to reject its eggs.
A light pinkish/purple background with a model of a uterus in light pink, dark pink, red, and white with light pink roses and red flowers making up the inside of the uteurus
Progesterone Pregnancy? We’re sharing everything you need to know about the topic and more!

Progesterone Pregnancy Levels

So, what is or isn’t normal when it comes to progesterone levels in early pregnancy? Here’s a breakdown of typical progesterone during pregnancy:

  • Pre-Ovulation: 1 – 3.18 nanogras per mililiter (ng/mL)
  • Mid-Menstrual Cycle: 5 – 20 ng/mL
    • If the egg isn’t fertilized, progesterone levels begin to decline 6 – 10 days after ovulation. 
  • 1st Trimester of Pregnancy: 11.2 – 90 ng/mL
  • 2nd Trimester of Pregnancy: 25.6 – 89.4 ng/mL
  • 3rd Trimester of Pregnancy: 48 – 300+ ng/mL

Within the first 24 hours of your postpartum period, your progesterone levels will decline swiftly.  Some experts believe this rapid change in hormone levels could even contribute to postpartum depression and anxiety

Side Effects of Low Progesterone in Pregnancy

In your everyday life, low progesterone levels can lead to frustrating side effects, such as abdominal pain, headaches, irregular periods, and low libido.  

Low progesterone during pregnancy, however, can lead to even more devastating situations.

Those of us who struggle with poor progesterone function in pregnancy are more likely to experience recurrent miscarriages or pre-term delivery

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Can Taking Progesterone in Early Pregnancy Help Prevent Recurrent Miscarriages?

In a 2020 study published by the American Journal of Obstetrics and Gynecology, researchers found that 8,450 additional babies could be born each year by ensuring normal progesterone levels in early pregnancy. 


In fact, due to this discovery, some researchers are now suggesting progesterone administration as a standard medical protocol in treating patients with a history of early pregnancy loss. 

But why? How could the connection between progesterone and pregnancy help physicians reduce the number of miscarriages their patients’ experience?

While a miscarriage can certainly be a spontaneous experience, for those of us who endure recurrent miscarriages, there is most often a specific reason why. Low progesterone during pregnancy is one of these reasons. 

Progesterone function in pregnancy helps prepare a the body to receive a developing embryo and helps support the growth and development of their baby throughout the gestational period. 

With low progesterone in pregnancy, embryos do not receive the nutrients and support required to become a viable pregnancy

It is worth noting, that scientists are still studying the benefits of taking progesterone in early pregnancy to reduce pregnancy loss. Current findings show progesterone is most helpful for women who have experienced at least three prior miscarriages

When to Start Progesterone to Prevent Miscarriage

While progesterone treatments usually start after ovulation during various fertility protocols, including IVF, the current standard for miscarriage prevention is slightly different.

If you’re wondering when to start progesterone to prevent miscarriage, many recent studies suggest beginning treatment at the first sign of early pregnancy bleeding.

If you’re curious about whether you might benefit from taking progesterone in early pregnancy, make an appointment with your doctor for more information.

Male doctor wearing a white shirt and holding a piece of paper sitting at a desk with a clipboard, pens, and a model of a uterus sitting in front of him
When battling conception troubles, you will undoubtedly hear about progesterone pregnancy. But how do these two things go together and can you have one without the other? We’re answering these questions and more!

What Side Effects Can You Expect When Taking Progesterone Tablets in Pregnancy?

If your healthcare provider decides to prescribe progesterone during pregnancy or after ovulation, it’s vital to understand what types of side effects you might experience. While some people feel fine, other experience symptoms, including:

  • Headaches
  • Irritability
  • Upset Stomach
  • Breast Tenderness
  • Runny Nose
  • Tiredness

Again, most of these are mild or non-existent. If you’re concerned about anything you’re feeling, don’t be afraid to consult with your doctor.

The Relationship Between Starting a Family and Managing Your Progesterone Levels

People often joke about the adverse effects pregnancy hormones can have. We blame mood swings, afternoon naps, and sudden cravings for pickles and ice cream on the various substances raging through our veins.

What many of us don’t understand, however, is just how much of a role hormones like progesterone plays on our ability to conceive and maintain a pregnancy. 

Progesterone and pregnancy are more closely tied than you can imagine. In fact, you might be surprised that this simple hormone could be the stepping stone to becoming the parent you long to be. 

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Have you had to take progesterone for pregnancy? What was your experience like?