Honestly, don't use Arnica gel or any other homeopathic treatments without asking your gynac first. Some herbs can absorb through the skin and aren't fully tested for pregnant women, so just check with your doctor.
I would highly recommend not using any such gels without consulting your doctor first. When you've faced difficult times before, you realize it's always best to be 100% sure about safety, so please call your gynac.
I am not very sure, but I think we should be extra careful with any herbal gels during pregnancy. Maybe you can ask your doctor before applying it, just to be on the safe side?
I would advise you to hold off on using Arnica gel until you speak with your doctor. Your skin is super sensitive right now and we don't know how it might affect the baby, so let's be safe.
Having gone through IVF, I became so cautious about everything I put on my skin. Please check with your doctor before using Arnica gel, as keeping you and your little one safe is the most important thing.
My back is killing me in this 3rd trimester, but my doctor told me to avoid random pain relief gels like Arnica without asking. Better to just use a hot water bag or ask your gynac for a safe cream!