What Is the Normal Size Uterus Before and After Pregnancy?

When studying the anatomy of a pregnant woman, we mainly study the uterus since it is where the majority of the pregnancy changes occur. The uterus, also known as the womb, plays a central role during pregnancy by providing a safe environment for the developing baby [1].

Throughout pregnancy, the uterus undergoes significant changes to accommodate the growing fetus. These changes mainly include an increase in the size of the uterus. The uterus grows from the size of an orange to a watermelon during pregnancy [2].

In this article, we will study anatomy of the pregnant woman, what is a normal size uterus, how uterus size changes during different phases of the pregnancy, and tips to support uterine health.

What Is the Role of the Uterus?

The uterus is a hollow, pear-shaped organ located in the pelvis between the bladder and the rectum [1]. It has several important functions, particularly during pregnancy. These are:

1. Nurturing the Baby

The primary role of the uterus is to provide a protective and nourishing environment for the baby to grow and develop. Before pregnancy, different changes occur in the uterus to make it suitable for the attachment of a fertilized egg.

Once the fertilized egg or embryo is attached to the uterus, it supports the further growth and development of the embryo through the placenta [3].

2. Attachment of the Placenta

The placenta is a temporary organ that attaches the embryo to the uterine wall during pregnancy [3]. This organ delivers nutrients and oxygen to the baby from the mother's blood. Similarly, it filters and removes waste products from the baby's blood.

3. Muscle Support

The uterus is made up of three layers: perimetrium, myometrium, and endometrium [1]. The perimetrium is the outermost layer that has a protective role. The myometrium is the middle muscular layer of the uterus that contracts during labor to deliver the baby. The endometrium is the innermost layer on which the baby attaches during implantation.

The Average Size of the Uterus Before Pregnancy

Questions like, what is normal uterus size, what is the normal size of uterus in cm, or what is normal size of uterus are commonly asked by women preparing for pregnancy. Before pregnancy, the uterine normal size is about the size of an orange [2]. The measurements of average uterine size before pregnancy include:

• Length: 7-8 cm (approximately 3 inches)
• Width: 4-5 cm (approximately 1.5-2 inches)
• Thickness: 2-3 cm (less than 1 inch)

If you are curious how much does the uterus weight, the non-pregnant uterus weighs about 50 to 60 grams — 1.7 to 2.1 ounces. At his time, it is present deep in the pelvis and doesn't form a bump that is apparent in pregnancy. For a detailed visual representation of the female reproductive system, explore the picture of womb and uterus to understand its structure and changes during pregnancy.

How the Uterus Size Changes During Pregnancy?

During pregnancy, the regular size uterus grows significantly in size, changes its shape, and stretches to accommodate the developing baby. Here are some details on different changes in uterus size during different phases of the pregnancy:

First Trimester

During the first trimester, the size of a normal uterus starts expanding to support the growing embryo. But what is the normal size of a uterus in the first trimester?

Reports show that by the end of the 12th week, the normal womb size is the size of a grapefruit and begins to rise above the pelvis [2]. However, it still fits into the pelvis by the end of the first trimester.

Second Trimester

In the second trimester, the uterus continues to expand rapidly since the baby significantly grows in size at this time of pregnancy. By 20 weeks, the uterus reaches the level of the belly button and resembles the size of a small melon.

Third Trimester

In the third trimester, the uterus becomes large enough to fill most of the abdominal cavity. But, how much do uterus weigh by the end of pregnancy? Or, how big is your uterus by the end of third trimester?

By the end of pregnancy, the uterus weighs about 2 to 4 pounds and holds 600 to 800 milliliters of amniotic fluid along with the baby and placenta [4]. Near the end of this phase, the myometrium — the middle layer of the uterus — starts to contract, which is an indication that delivery is near.

What Happens to the Uterus Size After Pregnancy?

After childbirth, the uterus begins the process of returning to its pre-pregnancy size, a process called uterus involution [5]. During the first few weeks after pregnancy, the uterus contracts to expel any remaining blood and tissue. These contractions, often called afterpains, help reduce its size to achieve the average size of a normal uterus.

After 6 to 8 weeks of delivery, the uterus typically returns to its pre-pregnancy size and position in the pelvis [6]. It is important to remember that every pregnancy is different and in some women, the real uterus may not achieve its pre pregnancy size.

Conditions That Can Affect the Uterus

Several conditions can impact the uterus and its ability to support a healthy pregnancy. These include:

• Uterine Fibroids: Fibroids are the non-cancerous growths that can develop on the uterine wall. This causes pain, heavy bleeding, or complications during pregnancy. Fibroids are very common, and reports show that about 70% of women develop fibroids in their lifetime [7].
• Endometriosis: A condition where tissue similar to the uterine lining grows outside the uterus. This causes pain but can also lead to serious complications like infertility. Endometriosis affects about 10% of women worldwide [8].
• Adenomyosis: Adenomyosis is a condition where the tissues that form the lining of the uterus start to develop inside the muscular layer of the uterus. This condition can lead to heavy bleeding during periods, discomfort, and infertility in some cases.
• Uterine Prolapse: When the pelvic muscle weakens and fails to support the weight of the uterus, the uterus may descend into the vaginal canal. This condition usually occurs after pregnancy, especially if one has multiple pregnancies.
• Congenital Uterine Abnormalities: While most of the uterine conditions develop later in life, some conditions are congenital. Some women are born with structural differences in the uterus, such as a septate or bicornuate uterus.

A septate uterus is when the uterus is divided into sections by a membrane, while a bicornuate is when the uterus has a heart shape instead of an inverted pear.

Tips to Support Uterine Health

If you are planning to conceive, it is essential to focus on maintaining uterine health since it is important for fertility, pregnancy, and overall well-being. Here are some tips that may help you support uterine health:

1. Eat a Balanced Diet

A diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats provides the essential nutrients that support uterine health. Nutrients like vitamins C and E, found in fruits and vegetables, are antioxidants that protect the uterine lining from damage [9].

Omega-3 fatty acids from fish or nuts also have anti-inflammatory properties and can reduce inflammation in the uterus, promoting a healthy environment for implantation.

2. Stay Hydrated

Drinking plenty of water keeps the body's tissues, including the uterus, hydrated and functioning properly. Proper hydration improves blood flow to the uterus, ensuring that it receives the oxygen and nutrients it needs to prepare for pregnancy and to support the developing baby during pregnancy.

3. Exercise Regularly

Gentle exercises such as walking, yoga, or swimming are excellent for reproductive health. Regular exercise enhances blood circulation to the pelvic region, including the uterus. This increased blood flow helps maintain a healthy uterine lining and reduces the risk of conditions like uterine fibroids [10].

4. Manage Stress

Chronic stress can increase the cortisol hormone, which leads to hormonal imbalances and affects the uterus and the menstrual cycle [11]. Stress management techniques like meditation and deep breathing help regulate cortisol levels, promoting a balance of reproductive hormones, such as estrogen and progesterone. These hormones are essential for uterine health before and after pregnancy.

5. Regular Checkups

Regular checkups with a gynecologist ensure early detection and treatment of uterine-related conditions. It can help identify issues like fibroids, infections, or endometriosis timely, preventing complications and supporting uterine health.

6. Consider Fertility Supplements

Supplements like folic acid, iron, or omega-3 fatty acids may support reproductive health. Folic acid supports cell growth in the uterine lining, iron prevents anemia, and omega-3 fatty acids reduce inflammation that could damage uterine tissues. You can get all the essential nutrients for female fertility in a single package in the form of fertility supplements.

Conclusion

The changes in the normal size uterus is an important discussion during pregnancy. The average uterus size grows from the size of an orange before pregnancy to the size of a watermelon by the end of the pregnancy.

The exponential growth of the uterus during pregnancy helps accommodate the rapidly growing baby in the womb. Near the end of the pregnancy, it starts to contract to expel the baby and other contents like placenta. The uterus returns to its pre-pregnancy size after about 6 to 8 weeks of delivery.

Uterus is susceptible to many conditions that may impact fertility health and pregnancy. Healthy dietary and lifestyle habits can help you support uterine health and lower the chances of such conditions.

FAQs

1. How big is a uterus?

Questions like what is a normal size of a uterus can help understand changes in the body during pregnancy. The normal size for uterus is about 7 to 8 cm before pregnancy. It is normally very small compared to its big size during pregnancy.

2. What is the normal size of womb by the end of pregnancy?

The usual size of uterus or womb by the end of pregnancy is about the size of a watermelon. This increase in size starts to become apparent from the second trimester in the form of a baby bump.

3. What is considered a large uterus in cm?

A uterus is considered large when its length exceeds 8 cm or its width is greater than 5 cm. This condition is known as enlarged nucleus and is usually caused by health conditions like fibroids and endomyosis.

Resources Used

1. Gasner, A., & A, A. P. (2023, July 30). Physiology, Uterus. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK557575/ 
2. Normal Uterus Size During Pregnancy. American Pregnancy Association. https://americanpregnancy.org/healthy-pregnancy/pregnancy-health-wellness/uterus-size-during-pregnancy/ 
3. Griffiths, S. K., & Campbell, J. P. (2015). Placental structure, function and drug transfer. Continuing Education in Anaesthesia Critical Care & Pain, 15(2), 84-89. https://doi.org/10.1093/bjaceaccp/mku013 
4. Amniotic fluid: MedlinePlus Medical Encyclopedia. (n.d.). https://medlineplus.gov/ency/article/002220.htm 
5. Uterus Involution. (2024b, May 1). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/22655-uterus-involution 
6. Lopez-Gonzalez, D. M., & Kopparapu, A. K. (2022, December 11). Postpartum Care of the New Mother. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK565875/ 
7. Yang, Q., Ciebiera, M., Bariani, M. V., Ali, M., Elkafas, H., Boyer, T. G., & Al-Hendy, A. (2021b). Comprehensive Review of Uterine Fibroids: Developmental Origin, Pathogenesis, and Treatment. Endocrine Reviews, 43(4), 678–719. https://doi.org/10.1210/endrev/bnab039 
8. Najmi, Z., Moradi, Y., Shams-Beyranvand, M., Khateri, S., Gharahjeh, S., Tehrani, S., Varse, F., & Tiyuri, A. (2021). A systematic review on the prevalence of endometriosis in women. The Indian Journal of Medical Research, 154(3), 446. https://doi.org/10.4103/ijmr.ijmr_817_18 
9. Traber, M. G., & Stevens, J. F. (2011). Vitamins C and E: Beneficial effects from a mechanistic perspective. Free Radical Biology and Medicine, 51(5), 1000–1013. https://doi.org/10.1016/j.freeradbiomed.2011.05.017 
10. Johnson, L. (2022, January 12). Fibroids and Exercise. Treatment for Uterine Fibroids With Embolization (UFE). https://fibroids.com/blog/health-information/fibroids-and-exercise/ 
11. Karunyam, B. V., Karim, A. K. A., Mohamed, I. N., Ugusman, A., Mohamed, W. M. Y., Faizal, A. M., Abu, M. A., & Kumar, J. (2023b). Infertility and cortisol: a systematic review. Frontiers in Endocrinology, 14. https://doi.org/10.3389/fendo.2023.1147306