XO fish soup is generally a pretty mild dish, just fish, broth, and vegetables, so the main things to think about are whether the fish is fully cooked through and whether the soup base has any strong alcohol content from the XO sauce itself. Most stalls cook the fish well done and the alcohol in XO sauce tends to cook off, but the amount can vary from stall to stall. It might be worth asking the uncle or aunty at the stall what goes into their XO base, just so you know what you are having. Since every pregnancy is a bit different, it would be good to check with your gynae or PD at your next visit if you are still unsure, just to be safe.