Ay, rashes during first trimester can happen talaga, kasi ang hormones are all over the place, but it's better to check with your OB just to be safe, especially kung hindi ka sure kung ano ang cause, some of us moms had heat rash or hormonal breakouts, pero iba-iba talaga ang katawan ng bawat mama. Wag mag-alala muna, pero get it checked so they can advise you properly on what's safe to use while pregnant, sis!