The physical changes during pregnancy include the transformation of the navel, medically known as the umbilicus. A pregnant woman’s belly button often changes from an “innie” to a flat surface or even an “outie,” a common and normal phenomenon known as navel eversion. This temporary alteration results from the body adapting to accommodate the growing fetus.
The Timing of Navel Eversion
The change in the belly button’s appearance does not happen early in pregnancy. During the first trimester, the uterus is contained within the pelvis, having little effect on the abdominal wall. The transformation usually begins later, most commonly in the second or third trimester.
Many women first notice their navel flattening or protruding between 26 and 30 weeks of gestation. The timing is highly variable; some individuals never experience a fully “popped out” belly button, finding it simply becomes shallow or flush with the surrounding skin.
The Physiological Reason for the Change
The cause of navel eversion is the increasing internal pressure exerted by the expanding uterus. As the fetus grows, the uterus rises out of the pelvic cavity and pushes against the abdominal wall. This outward force is directed against the umbilicus, which is a natural point of relative weakness in the abdomen.
The belly button is scar tissue, marking the former attachment point of the umbilical cord. The abdominal wall stretches significantly to accommodate the growing baby, and internal pressure pushes this scar tissue outward. Hormonal changes also contribute to the softening of connective tissues, making the abdominal wall more pliable and susceptible to outward pressure.
It is important to distinguish this common eversion from an umbilical hernia. A hernia involves abdominal tissue, such as intestine or fat, pushing through a small opening in the abdominal wall. While both result in a bulge, navel eversion is harmless, whereas an umbilical hernia may cause discomfort and should be monitored by a healthcare provider.
Factors Influencing Navel Appearance
Several individual factors determine if and how much a pregnant woman’s navel will change. The original shape of the navel is a predictor; a deeply inverted “innie” has more tissue to flatten before it can protrude. Women with a shallower navel are often more likely to experience eversion.
Women who have had prior pregnancies often experience navel changes earlier because their abdominal muscles and connective tissues have already been stretched. The amount of fat tissue surrounding the midsection can also influence the change, as a thicker layer may prevent internal pressure from prominently pushing the navel outward. Skin elasticity varies from person to person and affects how much the skin stretches and whether the navel becomes flush or fully everted.
Postpartum Resolution
The changes to the navel are temporary, resolving after delivery. Once the baby and placenta are expelled, pressure on the abdominal wall is immediately relieved, and the uterus begins shrinking back to its pre-pregnancy size. This reduction allows stretched abdominal tissues to gradually retract.
The belly button typically returns to its original shape within a few months postpartum. Some women may notice that their navel appears slightly different than before, perhaps less deeply inverted. The skin around the navel may also be affected by a temporary darkening, known as the linea nigra, which fades over time.