Hallow Dear, Masturbation by just clitoral tickling will not at all harm the baby in your womb. However, I would like to give you some more scientific advise regarding sexual relations during pregnancy. It is safe to have sexual intercourse between 14 weeks to 28 weeks of pregnancy if there is no specific contraindication. Later, physical contacts become quite bothersome and also the uterus is more irritable. During intercourse in the mid trimester, full insertion of penis into the vagina should be avoided. Partial insertion of penis in the vagina also gives good orgasm at the clitoris. Intercourse in side position prevents full insertion of penis. I hope this helps you. Dr. Nishikant