抓毛上身, 夠貼身嗎?? >> OK 貼身, don't buy a bigger size, bring your kid to try......I saw some kids wearing oversized 保暖 swimsuit during the swimming class & the kids keep trembling, I hesitated whether to tell the parents to buy a fit-sized to the kids....
The lower part of the body will always be in the water, so if it is warm water, that's should be ok.
Of course, if you are talking about out-door swimming pool, I guess a one-piece will be more suitable for beginners.