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How does the pregnant uterus change?

How does the pregnant uterus change?

Jun 25, 2022


Dr. Jacqueline Darna

Your uterus is just one organ group that will see lots of change during pregnancy. But my pregnant patients always ask, how will my uterus change? What type of uterus do I have? Can problems in pregnancy be a result of the health of my uterus? We will get into the answers to all your uterus questions, and if you don’t have time to read this, just listen to the Pregnancy Podcast Pukeology Episode 84 where I, your favorite doctor, explains how does the pregnant uterus change. Just remember almost all body systems change to ensure your body carries your pregnancy to term. Read to learn how your uterus changes during pregnancy.


What does the uterus do?

The uterus is one of the most vital organs that play a significant role in the female reproductive system.

It is pear-shaped and looks like a light bulk. When you are not pregnant, the size of your womb is almost the size of your fist, weighing about 1 ounce.


What is a normal sized uterus?

In addition, the uterus is small in volume when you are not pregnant, about 3 inches vertically and 2 inches wide.

The uterus is located in the pelvis and sits between the rectum and the urinary bladder. Various components provide support to the uterus. This includes the pelvic floor muscles, ligaments and the perineal body.

 how does the pregnant uterus change

The Womb

The parts of the uterus are as follows:

Cervix: This is the lowermost part of the uterus. It acts as a gate which dilates and allows your baby to pass through during vaginal delivery.

The body: Also called corpus.

The isthmus is the thin part of the uterus between the body and the corpus.

Fundus: This is the uppermost part of the uterus. It is also the widest part that connects the uterus to the fallopian tubes.

 what are the parts of the uterus

What is a endometrial?

The wall of the uterus is divided into three layers. The outermost layer that offers protection to the uterus is called the perimetrium. The middle layer, called the myometrium, consists of muscle which expands and contracts during labor to help in the expulsion of the baby. The innermost layer of the uterus is called the endometrium. This layer lines the uterus and is shed during the menstrual cycle. Ever wonder if that's why your pregnant belly is sometimes hard and sometimes soft? Listen to this Pregnancy Podcast Pukeology to get the pregnant answers. (Hint: it's not the endometrium because the latin word endo means within but it could be the other parts of your uterus.)

Listen to "Why Is My Pregnant Belly Sometimes Hard And Sometimes Soft? Pregnancy Podcast Pukeology Ep. 80" on Spreaker.


What is the function of the uterus?

The uterus has 3 major functions in your reproductive health. During pregnancy, the fertilized egg attaches to the uterus wall and allows your baby to grow.

The uterus also stretches during pregnancy, providing adequate room for your baby to grow and nutrients.

In addition, the uterus plays a role in the menstrual cycle. When fertilization fails to occur after an egg is released, the inner lining of the uterus slough off and is released out of the body as menses.

Your uterus also has a reflex called a vaso-vagal when tugged or pulled. Since it’s connected to the Vagus nerve, apart of your parasympathetic system, your heart rate may drop significantly with intense contractions or the pulling and tugging on it during a cesarean section (c-section). This is usually the most common reason for 80% pregnant women to experience nausea or vomiting during delivery, both vaginally and c-section. Placement of the epidural and inadequate hydration prior to placement (basically your dehydrated and need to be given more fluids via your IV) can also cause immediate vomiting.


Good news is there is natural relief for nausea and vomiting called NoMo Nausea Band. A 3:1 essential oil infused pressure bracelet designed for pregnancy and delivery and stops upset stomach in 30 seconds or less. NoMo Nausea is used in hospitals in over 175 hospital systems across the US, but don’t rely on your hospital to give you one, just order one on amazon or buy in store at Walmart or BuyBuy Baby. A $12 wristband can save you from giving up your cookies, and the hospital won’t give you a big meal until after you deliver so trust me you want to keep all your food down.


How does the pregnant uterus change?

The uterus undergoes a lot of changes when you are pregnant. The muscular layer of the uterus increases hypertrophies (growth, kind of like when you workout your muscles get bigger) leading to an overall increase of the uterus to about 35 by 25 by 22 cm. For this reason, the uterus grows beyond the pelvis into the abdominal cavity.

The weight of the uterus also increases 20 times from about 50 grams to 1000grams.

The total capacity of the uterus also increases 1000-fold from 4ml to about 4000ml. The blood floor to the uterus also increases 10-fold from 50ml/min to 500ml/min. This ensures that your growing baby in the womb gets enough nutrients and oxygen.

 how does the pregnant uterus change

What causes an enlarged uterus?

PREGNANCY! During pregnancy, the shape of the uterus also changes. It becomes globular by the 8th week of pregnancy and pyriform from the 16th week to the term. Pregnant moms that have an enlarged uterus are changing with the size of their baby. Think of the uterus as a hot tub protecting the baby, so if you have too much amniotic fluid that can cause an enlarged uterus. The medical definition of polyhydramnios is when there is too much amniotic fluid. Reasons for polyhydramnios is having multiples (twins, triples, etc.), gestational diabetes because the babies will be larger, and a blockage in the baby’s gut called gut atresia. Pregnant women with polyhydramnios may experience premature contractions, longer labor, difficulties breathing, and more.


Positions of the uterus

Uterus anteverted

Most women have an anteverted uterus. The uterus is slightly tilted toward the cervix, pointing towards the belly. However, some women have their uterus in a different position. These include:

Retroverted uterus, whereby the uterus tilts backwards.

Anteflexed uterus in which the uterus curves forward to the extent that it puts more pressure on your abdomen and bladder, causing pain.

A retroflexed uterus is a uterus that bends more towards your back, causing pressure on your lower back.

 pregnancy with bicornuate uterus

Getting pregnant with a retroverted uterus

Having a retroverted uterus does not affect your ability to conceive. However, your ability to conceive may be affected if the retroverted uterus is caused by other conditions such as fibroids, endometriosis or pelvic inflammatory disease.

In addition, retroverted pregnancy does not affect the viability of your baby. But you may experience urinary incontinence or difficulty passing urine and low back pain because getting pregnant with a retroverted uterus exerts pressure on your bladder and the low back.


Pregnancy with a bicornate uterus.

This refers to an irregularly shaped uterus that is shaped like a heart. As such, a bicornuate uterus does not have one hollow cavity. Usually, the uppermost part of the uterus is separated by tissues.

Women who become pregnant and have a bicornuate uterus have a higher risk of miscarriage and preterm labor. 

Regardless if you have a anteverted uterus, retroverted uterus, bicornate uterus, or even 2 uterus in pregnancy, it still takes a varying amount of time to get pregnant. Curious how long does it take to get pregnant? Compare how fast or slow you got pregnant to the statistics in the Best Pregnancy Podcast Pukeology Episode 75 & Best Pregnant Blog: How long does it take to get pregnant?

Listen to "How Long Does It Take To Get Pregnant? Pregnancy Podcast Pukeology Ep. 75" on Spreaker.

2 uterus pregnancy

Two uterus pregnancy is a double uterus (medically called uterine didelphys) which is abnormal and very rare. Having 2 uterus is a rare congenital (genes from your parents, say thanks a lot if you have it) abnormality. Usually when the mom was a fetus, the uterus starts out a two small tubes that usually join together to create one large uterus. Sometimes the tubes don’t join completely and that’s what causes a 2 uterus pregnancy. And in 2011 a woman in my home state of Florida gave birth to two babies, one in each uterus. The chances were one in five million, so that mama needs to play the lottery ASAP. Other 2 uterine births include one mommy having three babies a month apart.


Pregnancy outside the uterus

Any pregnancy that occurs outside the uterus is referred to as ectopic pregnancy. Therefore, a fertilized egg implants and develop outside the uterus.

Most ectopic pregnancies occur in the oviduct, but they can also happen in the ovary and the abdominal cavity. Most ectopic pregnancies do not grow to term.


How does the pregnant uterus change? Pregnant uterus summary…

The uterus plays a key role in your reproductive health. It is where the fertilized egg implants and grows into a baby. The uterus is also involved in the menstrual cycle. Most women have an anteverted uterus, while some have a tilted uterus. However, the tilted uterus does not affect the woman’s ability to conceive unless associated with other conditions such as fibroids. Bicornuate uterus happens when the uterus fails to form a hollow cavity completely and is associated with an increased risk of preterm labor and miscarriage. Pregnancy outside the uterus refers to ectopic pregnancy, which mostly occurs in the fallopian tubes.

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