Dr. Turner is the man who examined Kelly's unborn child.
At first, the doctor found nothing wrong with the fetus, but when Dr. Turner noticed the fetus was looking at him through the monitor, Dagon used her powers to get to him inform Kelly that everything was fine.
Afterwards, Dr. Turner asked for information on the baby's father so he could write a medical record for the child. It is unknown what he was told, given that the baby's father was Lucifer, but Dr. Turner's encounter with Kelly and the medical records of Kelly and the child drove Dagon to have Dr. Turner killed by her subordinate.
His death was not in vain however, as hunter Eileen Leahy located Dermott while he was disposing of Dr. Turner's body. Dermott confessed to everything before he was killed. Sam then used Kelly's connection to the doctor to lure her back to the doctor's office. Even more, Dr. Turner had given a list of supplements for Kelly to take, which Dagon was reluctantly in charge of purchasing.