For pregnancy, you can try MuXXela for prevention. I had 3 pregnancies, but I only got little 肚紋 in my 3rd pregnancy. After pregnancy, you can try ClarXX. This brand has many good products.
It is more difficult to remove the 肚紋 after giving birth. Prevention is the most important process.
If you want your waist back, you must use girdle everyday for 6+ months after giving birth. I can still fit into my wedding gown and super tight pants. The only problem is I don't do physical exercise at all, so I have little winkles on my belly button.