Meredith Borowiec, 31, is charged with second-degree murder in the 2008 and 2009 deaths of the babies, who were placed in garbage bags and dumped in a trash bin.
"I wanted to let them know something was happening with Meredith and her pregnancies — more than what was being told," Brittany Black, 28, testified in court on Friday.
Black and a number of other women had worked as servers, along with Borowiec, at an Irish pub in Calgary.
She said it was immediately clear to her that Borowiec was pregnant while they were working together.
"Her stomach was getting steadily bigger. She had the symptoms and signs of a typical pregnant woman. She would get moody," said Black. "At one point, she couldn't make it up the stairs and that's when the alarm bells went off for me."
"To me, it was very obvious Meredith was pregnant and it was coming to a full-term pregnancy."
But Black said after Borowiec took a few days off because she was ill, she came back with her stomach much flatter.
"Her belly was noticeably gone. She was noticeably thinner. She was happy. She was in a good mood," said Black.
"I asked what was going on and she started crying and told me she had a miscarriage."
Nadine Whelly was already working at the bar when Borowiec started working there. She also contacted police after hearing about the abandoned child.
"I did that because I had seen in the news that a baby was found in a Dumpster. I was contacted by former co-workers," said Whelly, 41.
"We believed it to be Meredith and because of where the baby was found. I contacted police because I witnessed two other instances where I think she was pregnant."
Whelly said Borowiec was obviously pregnant and when she returned from days off with a flatter stomach, she confronted her.
"I said, 'I know you were pregnant and I want to know what happened,'" said Whelly.
"She said, 'I wasn't pregnant. Okay, I was. I didn't want to deal with it. I didn't want to think about it,'" she added.
Allison Joudrey said when she first met Borowiec, her first assumption was she was having a baby and asked when it was due. She was told that the accused wasn't pregnant at all.
"She said she had uterine cysts and they would grow within her uterus and sometimes they had to be drained or removed," said Joudrey.
Both Joudrey and Whelly became emotional during their testimony.
"A few months later she started getting a small mass in her stomach...that again over a period of time started getting larger and larger," said Joudrey, choking back tears.
The court has already heard a police video interview with Borowiec in which she confesses to giving birth to the two newborns, putting their bodies in a garbage bag, and dropping them in a Dumpster.
She also said in the interview that she knew they were both alive when she disposed of their bodies.
A second trial for attempted murder involving the infant that survived is to be rescheduled this fall.
Her trial on second-degree murder charges was only scheduled to run six weeks and has now been adjourned until Nov. 4.
Borowiec's defence lawyers will seek bail for their client next Thursday.
Also on HuffPost