Dr. Mary Newport sees the symptoms more and more in the babies she treats: oddly stiff limbs, severe tremors, vomiting, diarrhea, insomnia, crying that never stops. The common denominator: Their mothers were taking prescription drugs, mostly painkillers like OxyContin and Vicodin, and antianxiety drugs like Xanax during pregnancy. Some of the moms had no idea these medications would hurt their developing babies — after all, it’s not like it’s heroin or cocaine, many think.