Story highlights The rate of babies born with the birth defect gastroschisis has increased significantly

For non-Hispanic black women under age 21, the rate rose 263%

(CNN) An increasing number of babies are being born with a serious birth defect, gastroschisis, and it's got scientists concerned.

The condition causes the intestines, and sometimes organs such as the liver and stomach, to poke through a newborn's abdomen near the belly button. It needs to be repaired through surgery.

The latest report from the Centers for Disease Control and Prevention finds that the number of cases of the birth defect nearly doubled from 1995 to 2005. The problem has continued to increase since 2005 for babies born to mothers of every race and age group. For non-Hispanic black women under age 21, the rate increased 263%, which was of particular concern, researchers said. Scientists tracked birth data in 14 states.

"It concerns us that we don't know why more babies are being born with this serious birth defect. Public health research is urgently needed to figure out the cause and why certain women are at higher risk of having a baby born with gastroschisis," said Coleen Boyle, the director of the CDC's National Center on Birth Defects and Developmental Disabilities.

The cause of the defect is unclear. It might be genetic, or it could be caused by the mother's exposure to something during pregnancy.

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