Yes. A study done by the University of Michigan, published April of 2008 in the American Journal of Obstetrics & Gynecology, determined that roughly 200 of the 370 fetuses killed every year in motor vehicle crashes in the United States could be saved if all pregnant women wore seatbelts. You're not doing yourself or your unborn baby any favors by foregoing the safety restraint. You're much more likely to damage your baby by going without a seatbelt.
Visit keepyourchildsafe.org for more safety information.