In the presidential debate Wednesday night, Donald J. Trump expounded on pregnancy and abortion, asserting that under current abortion law, “You can take the baby and rip the baby out of the womb in the ninth month, on the final day.”

Doctors say the scenario Mr. Trump described does not occur.

“That is not happening in the United States,” said Dr. Aaron B. Caughey, chairman of obstetrics and gynecology at Oregon Health and Science University.

“It is, of course, such an absurd thing to say,” he said. “I’m unaware of anyone that’s terminating a pregnancy a few days prior to delivery of a normal pregnancy.”

There can be situations where complications or problems occur late in pregnancy — if the woman was in a car crash, for example, or if she was suffering from severe pre-eclampsia, a potentially life-threatening condition involving high blood pressure.