VANCOUVER -- A Vancouver woman accused of murder in the deaths of her newborn sons was so scared of her parents finding out about her pregnancies that she gave birth alone in the family bathroom and then secretly disposed of the infants, says the Crown.

Sarah Leung, 28, was charged with two counts of second-degree murder after the body of a baby boy was found in a plastic bag outside an East Vancouver 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 prosecutor Sandra Cunningham told a 12-member jury on the first day of Leung's trial that after she was charged in June 2010, she 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 had become pregnant with his child.

Cunningham said the baby's father, who she did eventually marry, knew about the pregnancy and was happy about it, but she kept both their relationship and the baby 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 inside 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."

Cunningham did not specify precisely when the baby died.

Later on, Leung's father discovered the baby outside the home and had his son call the 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 the following year, 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.

The jurors heard Leung and her boyfriend got married in November 2009 and started to make plans about moving 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 -- once 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 then 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.

None of the allegations have been proven. Leung has pleaded not guilty.