Honestly, I'd check with your OB first about this one, mama, topical castor oil during first trimester is something best discussed with your doctor since pregnancy skin is so sensitive and every mama's situation is different. A few of us tried different oils during pregnancy, but most of us played it safe during the first three months and waited until second trimester, or asked our doctors which oils were okay specifically for us. Your OB will know your medical history best and can give you a proper answer, better to ask than worry, diba?