4 weeks pregnant, severe back pain. Waiting for doc to call back. Will taking 2.5mg Vicodin affect baby or cause birth defect?

Vicodin caution. vicodin contains hydrocodone, which is opioid, like morpheine, oxycodone, dilaudid, hydro morpheine, codeine, etc. They can cross the placenta and change the baby's chemistry. Taken chronically, they can cause opioid dependence in baby. Back pain in preg is usually mechanical. Ligaments and muscles are pushed around. A good osteopath or manually-trained physical therapist can often help.