"About seven months later I was given the all clear and fell pregnant to my second child, but after 10 weeks I miscarried."
She said losing two unborn babies shattered her and her husband Dan's dreams and they wondered if they were capable of having children.
Then, in 2008 Cornwall was invited to participate in the Auckland Stillbirth Study, which interviewed mums who had had stillbirths to identify risk factors during the pregnancy.
University of Auckland professor Lesley McCowan, who led the research that was followed up last year, said the study backed up international research that showed stillbirth was linked to pregnant women going to sleep on their back.
Last year's research showed that pregnant women who slept on their back from 28 weeks pressed on a major blood vessel which reduced blood flow to the womb and oxygen supply to the baby.
Cornwall said finding this out was life-changing.
"There wasn't a lot of control we had within the pregnancy with Mia [her first child] but the research empowered me with a bit more control over something I could physically do that was easy to help improve my chances of a normal pregnancy."
Since then, the 39-year-old has had two child whom she credits to McCowan's research.
"I hope that by sharing my story it will help prevent other parents from going through the horror we went through."
Each year, about 160 New Zealand babies are stillborn in the last three months of pregnancy.
This campaign, developed by the University of Auckland and Ministry of Health in partnership with child health research charity Cure Kids, aims to save at least 16 of those babies every year.
About one in 20 women in New Zealand go to sleep on their back in the late stages of pregnancy.
McCowan said going to sleep on your side halved the risk of stillbirth compared with going to sleep on your back.
"We're hoping this new information will have significant impact in changing habits."
