Hello there. I can understand your concern. Yes it is safe to have a baby. She can try for pregnancy but she might need some dose adjustment of her medicines so you will have to keep a close watch over her thyroid profile. Do not worry much, her obstetrician will take care of everything. But just be careful and go for timely check-ups and get tests done regularly. Other than that, everything will be just fine. Best regards. Dr. Anil kumar jain.