A young woman holding her 1-year-old daughter in a stroller was killed when she tumbled down a flight of Midtown subway stairs, police said Monday.

Malaysia Goodson, 22, fell down the stairs at the 7th Avenue B/D station at about 8 p.m., authorities said. She was rushed to Mt. Sinai West and declared dead, cops said.

Investigators are working to determine if she had some sort of fatal medical episode before she fell, or if she was killed by the impact from the fall, authorities said.

The medical examiner will determine her cause of death.

Goodson’s infant daughter was not injured in the fall, cops said.