WORCESTER — A couple here was charged with “concealing a fetal death’’ Tuesday, one day after the remains of what authorities described as a newborn were found in a plastic garbage bag in a wooded area near their home.

Authorities say that Jennifer Rheaume, 36, “admitted to disposing of the fetal remains by placing her baby inside a bag,’’ which she and her boyfriend then hid behind his mother’s Lake Avenue home.

Police made the grisly discovery Monday after a man went to the police station to report “an unusual odor coming from a bag.’’

“Inside that bag, there was discovered, tied up in multiple bags, a baby that was deceased,’’ Assistant District Attorney Kristin Salvatore said Tuesday.

Rheaume’s boyfriend, Edwin Santiago, 31, is accused of helping Rheaume dispose of the remains. Rheaume and Santiago pleaded not guilty Tuesday. Santiago was held on $50,000 cash bail, and Rheaume was held on $1,000 cash bail. Their next court appearance was scheduled for July 24. Santiago’s bail in an unrelated larceny case was also revoked.

Authorities said they are waiting on autopsy results to determine a cause of death and whether the baby was born alive.

At a news conference Monday, police said it was not clear when the body had been placed in the woods. Asked whether the infant might have been stillborn, or whether the remains were that of a fetus, Sergeant Sean Murtha said, “We’re calling it a newborn baby.’’

But Rheaume’s lawyer, Joseph Krowski Jr., said after Tuesday’s hearing that “we’re going to find out that this was nothing more than a very sad story and a tragedy.’’

“It certainly wasn’t a homicide. It wasn’t a manslaughter,’’ he said. “It was just a very, very sad situation that was brought upon this young woman.’’

Krowski said there is a “big distinction in the law, and in science’’ between a baby that has died and a fetus that “was never brought to fruition.’’

“Fetal remains is what the allegation is in this case,’’ he said. “And the only allegation is that there were fetal remains that were moved, no allegation that this child was ever born alive and that there was anything nefarious . . . brought on by my client.’’

Salvatore said Rheaume and Santiago had recently moved between homes on Lake Avenue, where Santiago’s mother lives. The couple had moved from her home into a neighbor’s basement but returned after they were kicked out.

The neighbor noticed the couple had left trash bags in his basement and asked them to remove them, Salvatore said. When they did, they allegedly hid the remains in a wooded area behind Santiago’s mother’s house, the prosecutor said. Police spotted Santiago and Rheaume walking nearby along railroad tracks. Salvatore said there is “strong evidence’’ tying them to the case. Salvatore said Santiago and Rheaume each have drug possession charges on their criminal records. Rheaume also has a prostitution charge, Krowski said.

Felicia Gans can be reached at felicia.gans@globe.com.