Seat belts work for everyone, including pregnant women. Like all occupants, they are more likely to be seriously injured if they do not wear seat belts.

A pregnant woman should wear a lap-shoulder belt, and the lap portion should be worn as low as possible, below the rounding, throughout the pregnancy.
The best way to protect the fetus is to protect the mother. When a seat belt is worn properly, it is more likely that the fetus will not be hurt in a crash. For pregnant women, as for anyone, the key to making seat belts effective is wearing them properly.
Lap-Shoulder Belt
Seat Belt Extender#PI0018B: Front or Rear Side Door Window Binds, Moves Slowly, Makes Rattle/Squeak Noise, Poor Fit/Misalignment or is Inoperative - (Nov 8, 2013) Doors
Subject:Front or Rear Side Door Window Binds, Moves Slowly, Makes Rattle/Squeak Noise, PoorFit/Misalignment or is InoperativeModels: 2008-2014 GM Cars and Light Duty Trucks This PI has been revised to add the 2014 model year. Please discard PI0018A.Condition/ConcernSome customers may comment th ...