The incident happened at 2:25 p.m. Friday the 3000 block of Stoney Creek Road in East Norriton.
Exactly how it happened is unclear but a gun, not a service weapon, apparently being handled by the trooper accidentally discharged, striking his wife JoAnna Miller.
She was rushed to Mercy Suburban Hospital where she was pronounced dead a short time later.
Autopsy results for JoAnna Miller and the baby were released Monday by the Montgomery County Coroner's Office. The cause of death for JoAnna was a gunshot wound to the head.
The 22-week-old baby was delivered during an emergency caesarean section, but the baby never had its own heartbeat and never breathed on its own.
The cause of death for the baby was lack of oxygen and pressure that occurred following the collapse of JoAnna Miller.
"There are two children that were in the residence, and they are being taken care of by family members," said Montgomery County First Assistant District Attorney Kevin Steele.
The trooper is a seven year veteran of state police stationed at the Skippack barracks. His late wife used to be a civilian employee of state police.
"Good people, I mean they kept quiet, kept to themselves. I mean when we had a tree blow down in a storm, they came up with a chainsaw and helped us cut the tree up," said neighbor John Silks.
"I can't imagine. It is unbelievable, especially here. I am just in shock," said Erin Gawlick.
Detectives from Montgomery County are working with East Norriton police on the investigation.