NBC is tweaking its fall schedule, replacing one new medical drama, Heartbreaker, with another, Chicago Med. The network last month announced a fall 2015 TChicago Med - Pilotuesday lineup consisting of The Voice leading to Heartbreaker and new variety show Best Time Ever with Neil Patrick Harris, to be succeeded by NBC Tuesday 10 PM anchor Chicago Fire in November, when Best Time Ever‘s run ends. Chicago Med, which originated as a planted spinoff episode of Chicago Fire this past season, was previously slated for a midseason launch but will now debut in September behind The Voice. Starting in November, it will form a Chicago 9-11 PM block, paired with the franchise’s mothership series.

The scheduling change stems from the pregnancy of Heartbreaker star Melissa George, who is expecting her second child. Both Heartbreaker and Chicago Med will start production in mid-summer, but Heartbreaker will then go on hiatus to accommodate George’s pregnancy. The show, based on the life of Dr. Kathy Magliato, is a starring vehicle, with George’s lead character Dr. Alex Panttiere, an outspoken heart-transplant surgeon, virtually in every scene, making filming around her impossible. New scheduling for Heartbreaker, which is recasting one of its male leads,will be announced soon.

Meanwhile, Dick Wolf’s Chicago Med had been quietly gearing up for an earlier start of production. The series, just hired a showrunner, Andrew Dettmann, and a new series regular, Colin Donnell. The series, described as an emotional thrill ride through the day-to-day chaos of the city’s most explosive hospital, will give Wolf four series on the fall schedule, the three Chicago dramas and Law & Order: SVU, as well as 2 two-hour 9-11 PM blocks, one on Tuesday and one on Wednesday.

Chicago Med also stars Oliver Platt, S. Epatha Merkerson, Laurie Holden, Nick Gehlfuss and Yaya Dacosta. Wolf, Dettmann, Matt Olmstead, Michael Brandt, Derek Haas, Arthur Forney, Danielle Gelber and Peter Jankowski executive produce.