A Trimester by Trimester Journey Through Pregnancy

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We know just how new and confusing learning about pregnancy levels can be so we have you covered. Progesterone is a key hormone to track during pregnancy as it can determine the health of your growing baby. Just think about the name of this hormone and you’ll understand exactly what it does for your pregnancy; it pro gestation!

In this article, we’ll walk you through the role of this hormone from your first to last week of pregnancy. We’ll explain your ideal progesterone levels at each trimester, who should prioritize tracking levels, and ways to regulate the hormone.

Trimester Journey Through Pregnancy

The Role Of Progesterone In Pregnancy

Want to know more about progesterone levels in early pregnancy or later trimesters? Progesterone is an important reproductive hormone that impacts your menstrual cycle, fertility, conception, and pregnancy health. During pregnancy, the hormone strengthens the innermost layer of your uterus, the endometrium. This is important for protecting and nourishing the fetus, stopping premature uterine contractions, and decreasing pregnancy risk. 

Low progesterone levels during pregnancy can result in potential miscarriages, stunted endometrium development, and ectopic pregnancies.

Progesterone Levels By Trimester

Below, we explain the ideal progesterone levels at each phase of pregnancy. However, what is considered an ideal or normal progesterone level can vary depending on the laboratory or medical center. If you are concerned about your levels, the values below can be a guide but it is important to consult with a medical practitioner. They can support you as necessary and explain what your specific levels and what they mean for you.

Trimester 1: 1-12 Weeks

The first trimester of your pregnancy is in the first 3 months. In this time, the luteal-placental shift happens. 

Before you fall pregnant, during your menstrual cycle, your body releases progesterone through the corpus luteum, cells that develop on your ovary during each cycle. Your progesterone levels during the first month of your pregnancy and your ovulation and luteal menstrual phases are the same:

Ideal Progesterone Levels (ng/mL)Ideal Progesterone Levels (nmol/L)
Week 1 & 20.1-0.7 ng/mL0.3-2.2 nmol/L
Week 3 & 42-25 ng/mL6.4-79.5 nmol/L

The corpus luteum continues this job until around week ten of pregnancy. From weeks 10-12, your placenta completely takes over this task. This handover is the luteal placental shift which often corresponds to a decrease in levels (see drops weeks 5 to 7 below).

Although the transition is complete at around 10-12 weeks, the transition should begin at weeks 6-8. An early shift can lower progesterone levels too much and lead to an early miscarriage. A complete shift after 9 weeks gives you a higher chance of a healthy pregnancy carried to term.

Ideal Serum Progesterone Levels (ng/mL)Ideal Serum Progesterone Levels (nmol/L)
Week 511.3-43.9 ng/mL 35.8-139.5 nmol/L 
Week 69.8-39.1 ng/mL31.3-124.4 nmol/L 
Week 710.3-32.5 ng/mL 32.9-103.5 nmol/L
Week 810.9-40.0 ng/mL34.6-127.2 nmol/L
Week 912.7-49.9 ng/mL40.3-158.6 nmol/L

Trimester 2: 13-26 Weeks

In the second trimester, your placenta has taken complete charge of making progesterone in the body. Progesterone levels rise again after the luteal placenta shift and continue to do so in this trimester. This helps with fetal development and supports a healthy pregnancy to term. Higher progesterone levels also promote milk production as you get closer to term.

In this stage of your pregnancy, normal serum progesterone levels range from 19.5 to 82.5 ng/mL or 62 to 262 nmol/L. There is a clear increase as compared to the first trimester.

Trimester 3: 27-40+ Weeks

In the final leg of your pregnancy journey, progesterone levels should continue to rise steadily. This prevents early labor and uterine contractions. Levels at this point vary between 65 to 290 ng/mL and 206.7 to 922.2 nmol/L.

Should You Track Your Progesterone Levels?

While it is important to understand the essential role of this pro-baby hormone as you navigate becoming a parent, it is not something to fret over. Irregular progesterone levels are not common and it’s even uncommon for medical practitioners to test for them. 

Practitioners may encourage tracking if you have multiple pregnancies, adrenal or ovarian cancer, or congenital adrenal hyperplasia. They may also have to monitor your levels if you’ve been taking progesterone supplements or they identify a molar pregnancy where the zygote leads to abnormal cell growth in the uterus. Women receiving IVF treatment or with a record of past miscarriages will also often have their levels regularly observed.

How To Regulate Progesterone Levels

If your doctor feels that you have low or high levels, they will advise you on the best action you should take to regulate your progesterone. This may include supplements such as injections, suppositories, or tablets. You can also take natural and lifestyle actions to aid this like keeping a healthy body weight, doing only moderate exercise, eating pro-progesterone foods, and decreasing stress. 

Avoid taking supplements or even progesterone creams without the advice of a medical practitioner. These can have unpleasant side effects.


Healthy progesterone levels are vital to a happy pregnancy and a growing, flourishing fetus. However, it is unlikely that this is something you have to add to your pregnancy list of things to worry about as you make plans for your 9-month journey. Most women do not have to closely monitor their levels at all. 

If you do have a history of miscarriages or face struggles with fertility, it is a good idea to consult with a doctor about your levels. They can suggest one of many ways to regulate progesterone levels to encourage a healthy pregnancy. It may also ease some of your anxiety to feel supported as you try to conceive or hope to have a successful pregnancy. 

No matter your pregnancy path, if you’re asking yourself about progesterone at any point, you can always come back to this article just to check-in.

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