So today i had my anatomy scan and everything seemed fine until it got to learning his weight and height. I'm a FTM so i had no idea but he was 11 ounces and only 8.87 inches long (i'm 20w5days) The doctor came in and asked me normal questions, did i smoke, did i drink before i knew i was pregnant, etc (All no i'm only 17 lol) Well it turns out my BMI is 17 and that's under the normal number (19) and they think that's the problem with why my son is so little. did anybody else have this problem? They said it may cause preterm labor or premie birth weight. I'm just worried be free to tell