Matthew Cherry, 35, attacked Caroline Craft, 27, at her flat in Bournemouth in 2011, because he did not want her to have his baby, Winchester Crown Court heard.
Miss Craft later gave birth to a healthy boy, who is now 15 months old.
Cherry resigned from Dorset Police in November last year, six months after the attack.
He had denied a charge of attempting to cause grievous bodily harm with intent. But the jury convicted him, rejecting his claim that he was not the attacker and was several miles away renovating a house.
Miss Craft, a fellow police officer, was SIX MONTHS pregnant when she answered the door of her ground-floor flat in Bournemouth, Dorset, thinking it was an estate agent who had come to view her property. Cherry, wearing a balaclava and using a fake foreign accent, then carried out a 'savage attack' on her.
Matthew Jewell, prosecuting, said: "She opened the door, which was then pushed violently from outside, and she was either pushed or punched to the floor.
"She was then attacked with multiple punches to her stomach and back, in a way which targeted her unborn child. She shouted for help and a gloved hand was placed over her mouth. She was also kicked.
"She pointed out valuable items in case this was a robbery or burglary but her attacker showed no interest in taking anything.
"She was dragged into the bathroom and forced to sit on the toilet. The male said he would tie her up. She was absolutely terrified about what was happening to her in her own home."
Miss Craft was left 'bloodied and bruised'. The attack only ended when the estate agent arrived. Cherry fled, using a back door, as he knew the block well having owned the flat before selling it to Miss Craft.
The Recorder of Winchester, Judge Keith Cutler, told Cherry:
It was a pernicious and evil attack. On your part there was a high degree of planning.
Jurors heard how he had earlier told Miss Craft and her flatmate that he had thought about punching her to cause a miscarriage.
He said the pregnancy had left him feeling trapped and had 'ruined his life', the jury heard.
They heard how Cherry was aware Miss Craft's flatmate was away in New York when he carried out the attack.
Footwear impressions found at the scene were left by size 10 Nike Dart trainers.
When Cherry's home was searched, a Nike box was found that had originally held size 10 Nike Dart trainers.
Analysis of CCTV footage, of a hooded man outside the flat before the attack, concluded he was 6ft 1in, the same height as Cherry.
The jury reached a unanimous verdict after seven hours of deliberation.
Miss Craft released a statement, saying:
The past 18 months have been a living hell. The actions of Matthew Cherry on that day were callous, cold-hearted and utterly selfish. I will never forgive him for what he did to me and what he so nearly could have done to my baby.