The Changes in Your Uterus During Pregnancy | Cervix Position

While we know that the uterus itself is hands down amazing, I want to share with you the science behind this organ and what happens to it throughout pregnancy.

The History of Your Uterus

As a fetus, the uterus is contained in the abdominal cavity.  At puberty, the uterus has descended into the pelvis with the folds being distinct and extending into the upper cavity of the organ. As an adult, the position of the uterus dependent upon the condition of the bladder and rectum.  When the bladder is empty, the entire uterus is tilted forward with the body lying on the bladder. When the bladder fills, the uterus becomes more erect leaving the fundus back toward the sacrum. During menstruation, the organ becomes enlarged, more vascular, rounder, swelling the labia, thickening, darkening, and softening the membrane lining of its body.  If pregnancy occurs, the uterus becomes enormously enlarged throughout the fetal growth period.

Positions of the Uterus

Anteversion – uterus and cervical axis oriented toward the pubic bone Anteflexion – uterus oriented toward the pubic bone, with the anterior portion of uterus concave Anteversion and anteflexion – a combination of the above Retroversion -uterus and cervical axis oriented toward the sacrum Retroflexion – uterus oriented toward the sacrum, with the anterior portion of uterus convex Retroversion and retroflexion – a combination of the above Retrocessed – top and bottom of uterus are pushed toward the sacrum Midposition/Vertical – uterus points straight upward toward the diaphragm As you can see from the image, the position of the uterus has a domino effect reaching even the position of the cervix, bladder, and rectum. With severe retroversion or retroflexion, the uterus is pulled to the back of the body to the point that the cervix is pulled onto the anterior (top) wall of the vagina. For the opposite (and less symptomatic) position of severe anteversion or anteversion, the uterus would be found more on the posterior (bottom) wall. Many women suffer from side effects of a displaced uterus, including: pelvic pain, irregular menses, painful menses, pain with sex (particularly with deep penetration or thrusting), severe back pain in early pregnancy, recurrent urine infections or urine retention, miscarriage, feeling of pelvic congestion, problems with intrauterine contraception, size larger than dates in early pregnancy, varicose veins in the legs, chronic constipation or pain with bowel movements, and, some may say, infertility. Note: If you feel as though you suffer from a displaced uterus due to endometriosis, fibroids, pelvic inflammatory disease/salpingitis, multiparty, lack of abdominal muscle tone, genetics, or abdominal surgeries including cesarean section, talk to your midwife about treatment options.

The Anatomy of the Uterus

Creating the strongest muscle, by weight, in the human body, the parts of the uterus are important to understand. The uterus is a hollow, thick-walled, muscular organ situated deeply in the pelvic cavity between the bladder and rectum. The uterine tubes open at the top, one on either side, while below, its cavity works with the vagina. When the eggs are discharged from the ovaries during ovulation, they are carried to the uterine cavity through the uterine tubes. If an ovum (egg) is fertilized, it imbeds itself in the uterine wall (Implantation) and is normally retained in the uterus until prenatal development is completed. The uterus undergoes changes in size and structure to accommodate itself to the needs of the growing embryo. After birthing, the uterus returns almost to its former condition, as it will always show proof that it has held a baby. The uterus measures about 7.5cm in length, 5 cm in width, and at its most upper part, it measures 2.5cm thick.  The uterus weighs in at 1-1.5 ounces. It is divisible into two portions: The body and the fundus.

Sustaining an Early Pregnancy

  As the ovaries produce estrogen and progesterone to thicken the lining of the uterus during the menstrual cycle, they continue to produce the hormones to sustain a pregnancy until the placenta has formed and is able to provide what is needed for the growing baby.

Changes throughout pregnancy

The first change in the uterus happens when the egg is implanted in the first week. The implantation itself is not noticeable, but is generally accompanied by slight bleeding five to 10 days afterward. The amount of blood is so slight that most women do not notice it. Pregnancy cramps are another common symptom. The feeling is similar to menstrual cramps, and is caused by the uterus' expansion to accommodate the growing fetus inside. Sharper, but similar, aches may be attributed to round ligament pain. The uterus is held in place by ligaments that must stretch to help stabilize the growing uterus during pregnancy. This stretching can cause temporary pain, especially with sudden movements. By the end of the pregnancy, a woman's uterus will extend from her pelvis to the bottom of her ribcage. It will weigh 15 times more than before pregnancy — not including the fetus — and can hold 500 times more than it did prior to conception. The larger uterus is one of the reasons many women often have the urge to urinate frequently during pregnancy, since the larger uterus presses down on the bladder while simultaneously suppressing its capacity. The uterus grows an entire organ (the placenta) to sustain a new life.  It also houses the amniotic cavity which, as you can see in the photo above, is home to the amniotic fluid, the fetus, the placenta, etc. Below you can see how quickly the uterus grows during pregnancy.

Returning to Normal After Birth

Within one week of giving birth, the uterus has shrunk down to under a pound, and by 6 weeks it is back to its normal size and weight.  This takes many contractions and the exact timing is dependent on how well the mother is healing, her core strength, and how she birthed. The complexity of the uterus’ design and function is awe inspiring   References:
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