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 ExtenderSmartphone Link (Stitcher)
Some images and explanations may vary by phone operating systems, versions, and/or
application (App) versions.
Using Stitcher
Install the Stitcher application on the smartphone.
Connect the smartphone to the infotainment system through the USB port or
Bluetooth wireless technology.
...
Adding Equipment to the Airbag-Equipped Vehicle
Adding accessories that change the vehicle's frame, bumper system, height, front
end, or side sheet metal may keep the airbag system from working properly. The operation
of the airbag system can also be affected by changing any parts of the front seats,
safety belts, the airbag sensing and ...
Infotainment
Read the following pages to become familiar with these features.
Warning
Taking your eyes off the road for too long or too often while
using any infotainment feature can cause a crash. You or others could be injured
or killed. Do not give extended attention to infotainment tasks while driving. ...