Safety belts work for everyone, including pregnant women. Like all occupants, they are more likely to be seriously injured if they do not wear safety 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 safety 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 safety belts effective is wearing them properly.
Lap-Shoulder Belt
Safety Belt ExtenderShock Absorber Disposal
Warning: Gas charged shock absorbers contain high pressure gas. Do
not remove the snap ring from inside the top of the tube. If the snap
ring is removed, the contents of the shock absorber will come out with extreme
force which may result in personal injury.
Warning: To prevent personal inju ...
Installation Procedure
Cut the quarter outer panel in corresponding locations to fit the
remaining original panel. The sectioning joint should be trimmed to
allow a gap of one-and-one-half-times the metal thickness at the sectioning
joint.
Create a 50 mm (2 in) backing plate from the unused portion
&nbs ...
How Does an Airbag Restrain?
In moderate to severe frontal or near frontal collisions, even belted occupants
can contact the steering wheel or the instrument panel. In moderate to severe side
collisions, even belted occupants can contact the inside of the vehicle.
Airbags supplement the protection provided by safety belts ...