Beta, do not use chemical hair dyes during these delicate months. It is much safer to use home remedies like natural henna or indigo powder if you really need to cover them. Even then, apply it carefully and don't catch a cold.
I am currently trying to conceive and was wondering about this too. I have read that ammonia-free hair colors are safer, but I am too shy to ask my doctor yet. I think sticking to natural henna is the safest path to avoid any risks.
There is no conclusive proof that hair dye is harmful, but most doctors recommend avoiding chemical dyes in the first trimester. If you must color, go for ammonia-free, plant-based dyes or highlight instead of scalp application. Honestly, check with your gynac first.
I strictly avoided chemical dyes and stuck to organic henna just to be safe. Keeping active with my daily walks allowed by my doctor helped me stay positive about my changing look. Check with your doctor before using any commercial colors.
When I stayed with my parents, my mother strictly forbade me from using chemical colors. She used to make a safe paste of organic henna and amla at home for me. It was so soothing and gave a beautiful natural tint without any harmful chemicals.