Cold stuff during pregnancy

A friend told me no cold drinks better cos she did that and her son is super prone to cough/phlegm etc. But SG weather so hot lah. I cannot and must drink cold water 😅 it helps me better with my morning sickness better than warm drinks too. Watermelon I haven’t had them yet but will want eat when I see them. Except that I will avoid those cut already for some time cos heard watermelon absorbs the bacteria very fast once cut. Not sure about that though