Your Baby's Development Your baby is still receiving oxygen
through the placenta. But once birth occurs, his or her lungs
will start taking in oxygen on their own. In preparation for
that, your baby's lungs are developing the ability to produce
surfactant. Surfactant is a substance that keeps the air sacs in
our lungs from collapsing and sticking together when we exhale,
allowing us to breathe properly. Because the inner ear — which
controls balance in the body — is now completely developed, your
baby may be able to tell when he or she is upside down or right
side up while floating and making movements in the amniotic
fluid. An important prenatal test, glucose screening, is usually
performed sometime during weeks 24 to 28. The glucose screening
test checks for gestational diabetes, a temporary type of
diabetes that occurs during pregnancy and can cause problems in
the newborn, such as low blood sugar. Gestational diabetes may
also increase the chances that a woman would need a cesarean
section because it can