Sarah Leung, 28, was charged with second-degree murder after the body of a baby boy was found in a plastic bag outside the home in April 2009.
Police alleged Leung gave birth to a second baby boy in March 2010 and killed that baby as well, though the infant's body was never found.
On Monday, Crown lawyer Sandra Cunningham told a jury on the first day of Leung's trial that after she was charged with another count of second-degree murder in June 2010, Leung confessed to police that she was afraid to tell her parents about her pregnancy.
"She told (a detective) her parents didn't really approve of getting pregnant before marriage, and she was scared to tell them because she knew they would be unhappy," Cunningham said in her opening statement.
"She knew she had done something wrong against them, that they wouldn't have liked, so she hid everything from them."
During Monday's hearing, the lawyer laid out a sequence of events that police believe led to the deaths of the two baby boys.
Leung, wearing jeans and a black jacket over a grey hooded sweater, listened quietly.
Jurors heard that Leung was dating a man and became pregnant with his child.
Cunningham said the baby's father, who she eventually married, knew about the pregnancy and was happy, but she kept their relationship and her pregnancy from her family.
In April 2009, Leung delivered the baby into a toilet at the home where she continues to live with her parents and brother, Cunningham told the jury.
Afterwards, Leung put the baby in a plastic bag, cleaned up any signs of her delivery and told her boyfriend that she had a miscarriage, Cunningham said.
"She put her baby boy, still, inside the plastic bag, outside between her house and the next door neighbour's, and carried on as if nothing had happened," she said.
"No one suspected a thing."
Leung's father later discovered the baby outside the home and had his son call police. When Leung's parents told her about the police investigation, they did not think her reaction seemed unusual, Cunningham said.
"She reassured them she knew nothing about the baby or how it came to be in a plastic bag outside," the lawyer said.
In August 2009, police determined from DNA tests that the dead baby belonged to Leung and her boyfriend. By this time, it was likely that Leung was already pregnant with her second child, Cunningham said.
Jurors heard Leung and her boyfriend were married in November 2009 and were planning to move in together after the baby was born. However, Leung kept the marriage and her pregnancy from her family.
In March 2010, Leung gave birth to her second baby boy — again into a toilet at her parents' home.
Cunningham alleged Leung put the baby inside a plastic bag and held him against her chest to keep him quiet. The baby stopped moving, she said.
Leung then put the plastic bag inside a garbage can outside her house and covered it with a piece of cardboard, Cunningham alleged.
She said the garbage was picked up, and the baby's body was never found because police decided a search at the landfill would be unsuccessful.
On Monday afternoon, Leung's mother, whose name is covered by a publication ban, testified that Leung is a quiet, self-conscious young woman who rarely talked about her personal relationships.
She said she didn't notice anything physically or emotionally different about her daughter leading up to the day her husband found the first baby outside their home.
Leung's mother said she and her husband taught their children to respect themselves and their elders, study and work hard, and value family. She disapproves of sex before marriage, and cannot accept her children having casual sexual relationships, she said.
"If you have the bond of marriage there, then on both sides there would be a goal when you do something and you'll cherish each other more," she said through a Cantonese interpreter.
None of the allegations have been proven. Leung has pleaded not guilty.
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