The common expectation during pregnancy is that the growing belly will cause the navel to protrude, transforming an “innie” into an “outie.” It is entirely normal for the belly button to remain an “innie,” or simply flatten, throughout the entire pregnancy. Whether or not the navel changes shape depends primarily on the unique anatomical structure of the individual’s abdominal wall and the original configuration of the navel itself.
The Anatomy of the Outie
The belly button (umbilicus) is the scar left when the umbilical cord is severed. It is composed of scar tissue and skin, making it the thinnest part of the abdominal wall. The change in its appearance is a direct result of the internal pressure generated by the expanding uterus.
As the uterus grows, typically reaching the level of the navel around the 20th week, it pushes the entire abdominal structure outward. This pressure causes the skin and connective tissue surrounding the navel to stretch. For the navel to “pop out,” the pressure must be significant enough to overcome the natural indentation of the scar tissue. This outward projection is a cosmetic change, simply the navel being pushed flush with or beyond the surrounding skin surface.
Factors That Keep the Belly Button In
The reason some people never experience the “pop” is due to anatomical variables that resist internal pressure. One significant factor is the initial depth of the navel. A naturally deep “innie” has more inward-folding skin and scar tissue, requiring greater outward stretching to flatten or reverse its shape.
The layer of subcutaneous fat tissue between the skin and the muscle fascia also acts as a natural buffer. This fatty layer cushions the abdominal wall, absorbing some of the pressure from the expanding uterus and preventing the navel from being pushed fully forward.
The natural elasticity and tone of the abdominal muscles influence the outward movement. Stronger or less stretched muscles offer more resistance to the forward projection of the uterus. This resistance limits the overall degree of abdominal wall distension, reducing the pressure placed directly on the navel. The specific position of the fetus or the placenta can also subtly alter how the internal pressure is distributed across the abdominal wall.
Related Concerns: Umbilical Hernias During Pregnancy
Distinguish the normal, painless cosmetic protrusion of the navel from an underlying medical condition. The benign “outie” is simply stretched skin and scar tissue. In contrast, an umbilical hernia involves actual tissue (often part of the intestine or fatty tissue) pushing through a weak spot in the abdominal muscle wall near the navel.
This occurs because pregnancy increases intra-abdominal pressure, which can worsen an existing weakness or create a new one in the fascial ring around the umbilicus. Symptoms often include a soft bulge that may become more noticeable when coughing or straining. Unlike the normal change, a hernia can sometimes be accompanied by discomfort, tenderness, or a dull ache in the area.
If the protrusion is painful, hard to the touch, or cannot be gently pushed back in, this may indicate a complication, such as a trapped or strangulated hernia. Any sudden, severe pain or change in the bulge’s consistency warrants immediate consultation with a healthcare provider. Most umbilical hernias that appear during pregnancy are small, resolve naturally after delivery, and do not pose a danger to the mother or the developing baby.