The best way to figure out your ideal weight — and weight gain — is to look at a measurement that’s known as body mass index (BMI), a number that takes into account both height and weight.
Find your body mass index by looking up your measurements on the chart. Locate your weight on the vertical line on the left-hand side of the chart and your height on the horizontal (bottom) line. (Alternatively, use the metric measurements on the right-hand and top sides.) Find the place where those two points intersect on the chart, and then follow the diagonal line closest to that point to find your BMI.
![[Credit: Source: Nutrition During Pregnancy and Lactation, The National Academies Press, 1992]](https://cdn.prod.website-files.com/6634a8f8dd9b2a63c9e6be83/669a1e7ebef766d6ae962e72_437983.image0.jpeg)
After you know your body mass index, you can figure out your ideal weight gain during pregnancy by consulting the following table. (But don’t forget, this number refers to women carrying only one baby!)
| Body Mass Index | Recommended Weight Gain |
|---|---|
| Less than 19.8 (underweight) | 28 to 40 pounds (12.5 to 18 kilograms) |
| 19.9 to 26 (normal weight) | 25 to 35 pounds (11.5 to 16 kilograms) |
| 26 to 29 (overweight) | 15 to 25 pounds (7 to 11.5 kilograms) |
| 29 or more (obese) | 15 pounds (6 kilograms) or less |
These numbers refer to total weight gain during the entire pregnancy, so you won’t know whether you’ve hit the target until delivery day. Scientific research hasn’t determined the optimal pattern of weight gain throughout pregnancy.
Gaining very little weight early on (when you may be in the throes of morning sickness) may have less effect on fetal growth than poor weight gain in the late second or third trimester. Some women gain weight inconsistently, putting on a large number of pounds early and then much less later on. Nothing is necessarily unhealthy about this pattern, either.
