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I am 4'10 1/2 and have never weighed more than 100 pounds. I'm also 20 years old. I am now 20 weeks pregnant and look the same as I did when I was 12 weeks pregnant. My belly is smaller than all the other women I know. Baby boy is completely healthy and measuring on time. However I do have a low lying placenta right know. I'm just worried my belly will never pop. When did all you other petite ladies pop?