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Why does the uterus rise into the abdominal cavity as pregnancy progresses?
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prenatal development
An ultrasound image of a human fetus.
As pregnancy progresses, the uterus rises into the abdominal cavity primarily due to its significant increase in size. In an adult, the nonpregnant uterus is approximately 7.5 cm long, but it enlarges to four to five times this size during gestation.1
This physical expansion necessitates a shift in position, moving the organ upward from the pelvis into the abdomen, which also results in a closer alignment with the vagina. As the uterus grows, it exerts pressure on surrounding structures, including the fallopian tubes, which stretch upward alongside it, and the diaphragm, which is pushed upward as the pregnancy advances.123