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 ExtenderEngine Component Description (LFX)
The High Feature V6 (VIN Code Identifier “3” for both cars and trucks) RPO LFX isa 3.6-Liter VVT-(Variable Valve Timing) engine with direct injection. The LFX hasE85-compatible valves and seats with special materials and coatings that require slightlydifferent service procedures from gasoline va ...