Normal weight women (BMI of 18.5-24.9) should gain about 25-35 pounds during their pregnancies. Underweight women (BMI < 18.5) may need to gain more and overweight women less. For obese women (BMI > 30), dieting is safe and beneficial during pregnancy. Most weight gain comes in the second half of pregnancy and often women have gained no weight or even lost weight by their 20th week; this is healthy and okay.
We check your weight at every visit, but please don’t focus on how much you gain. We are usually not worried about you gaining too little weight but instead gaining too much weight. Excess weight gain increases the risks of several pregnancy complications, including the risks of preeclampsia, diabetes, fetal macrosomia (a big baby), and Cesarean delivery.
Many overweight women can gain no weight for the entire pregnancy or even lose some weight if they’re actively dieting. This is not a bad thing. Maternal weight gain, if it is excessive, is associated with a larger fetal size; but that doesn’t mean that gaining too little weight during pregnancy will not make your baby too small if you are overweight at the start of the pregnancy. The goal is to have a healthy baby and a healthy mom. Talk with your doctor or midwife about what your weight journey should look like throughout pregnancy based on your pre-pregnancy weight.