A Ramsey County judge on Monday threw out a prosecutor's amended complaint in which he sought to upgrade charges by claiming a woman used her hands and medical training as "dangerous weapons" when smothering her baby at a local hospital.

The judge ruled that Katie E. Lewis will remain charged with third-degree assault, child endangerment and domestic assault by strangulation of her 5-month-old baby at Children's Hospital on May 2.

Those felonies would bring probation if Lewis, 24, of Litchfield, Minn., is convicted.

Assistant Ramsey County Attorney C. Ryan Tennison was pushing for a prison term when he proposed upgrading third-degree assault charges to second-degree assault with a dangerous weapon.

Tennison argued that Lewis' training as a nursing assistant, including knowledge that infants primarily breathe through their noses, and the vulnerability of her baby constituted use of her hands and medical knowledge as weapons. Tennison said medical staff members at Children's Hospital videotaped the May 2 assault, which shows the baby's vulnerability.

But defense attorney Michael C. Davis argued there wasn't enough evidence to support the allegation that Lewis' hands and medical knowledge were dangerous weapons.

"She certainly wasn't trained to cut off air supplies," he said Monday in Ramsey County District Court.

Judge Judith Tilsen agreed with both sides in some respects but said she didn't think a jury would find Lewis' hands to be dangerous weapons.

Tilsen let the three original felony charges stand while rejecting the amended complaint. A pretrial hearing is set for Dec. 21, with trial in January.

Lewis, who dabbed away tears during the hearing, declined to comment afterward.

In McLeod County, a trial is to begin Dec. 11 to terminate her parental rights for baby Carson W., who's in a foster home, and for an older child.

The Ramsey County criminal complaint says Carson was admitted to Children's Hospital on May 1 after being monitored and tested at the hospital for days. Lewis told the medical staff that on multiple occasions, her son would stop breathing, turn blue, then regain consciousness.

Mother and son were left in a hospital room equipped with cameras and video and audio recording systems. On May 2, a nurse watched as Lewis pinched Carson's nose closed while covering his mouth and nose for 45 seconds.

"The infant kicked frantically when he could not breathe," the complaint states. "He then went limp and unresponsive in Defendant's arms.

"When medical staff rushed into the room, [Lewis] claimed: 'His heart rate went down and he turned blue.'"

She told police that she was frustrated with her child-care responsibilities and that beginning last February, she held her baby's nose and mouth closed in repeated incidents.

Joy Powell • 651-925-5038