The trooper was cleaning a .45 when it went off and hit his pregnant wife JoAnna Miller, killing her.
Police say the trooper didn’t know the gun was loaded when he pulled the trigger.
Miller was pronounced dead at a Pennsylvania hospital. The child was delivered by c-section but the coroner said, "the baby never had its own breathing or heartbeat."
Cops say the unnamed husband was the only other person adult in the house at the time and was reported to be "distraught" and "cooperative." Concerned neighbors told investigators the couple was happy, friendly, and didn’t seem to have any marital troubles.
The couple has two other children who were home at the time but were not injured.
Miller was 22 weeks pregnant at the time of her death.