If i used issopropyl alcohol to clean lotion off my stomach while pregnant, can it harm the baby?

No: No, it isn't absorbed into the skin and your bloodstream.

The general rule: Over the counter medicines/lotions/creams that you may apply to your skin surface are not absorbed into the blood in any significant degree. For that reason they are not a risk during pregnancy or breastfeeding. Any prescription meds you may need to apply must be cleared first by your doc for such use.