Figure 4. Crossing Points for the Small for Gestational Age (SGA) and Large for Gestational Age (LGA) Curves by Body Mass Index Category.

Solid circles represent the crossing points; bars indicate optimal gestational weight gain (GWG) ranges recommended by the US Institute of Medicine (IOM). The line indicates the linear fit of the crossing points: optimal GWG (in kg) = (−0.932 × prepregnancy body mass index) + 41.5. Body mass index is calculated as weight in kilograms divided by height in meters squared.