It happened Feb. 25 just before 6 p.m. on a J train at Jamaica Center-Parsons/Archer station.
The woman, who is seven months pregnant, was approached by the suspect and punched in the face, causing cuts, bruises and pain to the right eye. The victim was checked out but was not taken to the hospital.
Police are searching for the suspect, who ran away after the attack.
He is described as having facial hair and was last seen wearing a black coat, blue jeans and black and white shoes.
The subway station has private security guards contracted by the MTA to deter fare beaters, but violent crime is what riders are most concerned about.
Felony assault on the subway is down 16.7% this year, according to NYPD data. That follows a show of force in January of a surge of hundreds of cops into the system, with at least two officers riding every train overnight.
Despite the city and state's effort to address crime and homelessness in the subway, many riders told Eyewitness News that they believe there is still more work to do.
Anyone with information is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
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