My sister-in-law and I were laughing at this. We're both Chinese, but also conscientious and educated, and read up on both Western and Chinese rules. What was funny is that they are often in total conflict. U.S. sources say that watermelon is a refreshing way to deal with nausea and a good source of Vitamin C. The Chinese say not to eat it -- but for no reason other than that old "cooling" superstition.
This conversation led to some aunties argue whether the rule applies to all melons, bittermelon, watermelon, or what. Seriously, they can't even get their own rules straight. And the rules are different between, say, Southern and Northern Chinese -- which goes to show that the whole "Chinese women are built different" argument is just bosh!
We're all joking here -- but the reality is that if an expectant mom takes this too seriously, she could be cutting out essential fruits and vegetables from her diet. I find it hard enough eating well -- while working full-time -- while ignoring all these superstitions. What if you believed the old wives tales and were not eating bananas, melons, cool water, lychee, mangos, healthy smoothies, or anything?
When I'm at work, I'm happy if i can find a good fruit salad instead of junk food. Thank God I can think on my own and eat it without worrying.
P.S. One Chinese lady told me that if I drank cold water, my child would shiver uncontrollably in life. I replied that, if that was true, the whole Western hemisphere would be shivering all the time!