Have you seen the latest weight gain recommendations from the IOM? They are the same except an increase for the highest BMI levels. Low BMI gain 28-40 pounds; Normal BMI gain 25-35 pounds; High BMI gain 15-25 pounds and Obese BMI gain 11-20 pounds.
I personally am a fan of increasing the weight gain for obese individuals. I’ve always been frustrated that to ensure the recommended weight gain it meant an obese woman actually losing weight during pregnancy (when you adjust for the growth of the baby and the placenta). I prefer to focus on what a woman eats, and if her nutrition is appropriate than not worry so much about the number on the scale.
But my mind may have been changed recently. As we discussed prenatal nutrition, one of my instructors pointed out that it can be very difficult for an obese woman to gain “enough” weight during pregnancy (with enough meaning the recommended weight gain) because to maintain her body weight takes a significant amount of calories. During early pregnancy, with nausea and food aversions many women (obese included) have difficultly consuming their customary amounts of food. Without the high caloric intakes to maintain the weight, obese women often lose significant numbers of pounds early in pregnancy. I hadn’t really thought about that before, but it does make sense. Maybe I can be a little less frustrated with the weight gain recommendations now.
So how do you know if a woman is eating an adequate number of calories during pregnancy? You do the math. The equation is to take her optimum prepregnancy weight in kg (about the middle number of the normal BMI for her height or use the old Metropolitan Life Charts), and multiply that number by 35 calories. This is her pre-pregnancy calorie need. Add 300 to the number and that is about the number of calories she needs everyday for a healthy pregnancy.
There is another method, called the Higgins Intervention Method, that Varney’s Midwifery introduced to me. Created by the Montreal Diet Dispensary, it uses charts of the desired weights by height (those Metropolitan Life Charts again) and charts of calorie requirement for weight and activity level (From the Canadian Dietary Standards for Female Adults). This method seems to add 500 calories and 25 grams of protein per day after 20 weeks pregnancy without any increase prior to 20 weeks. For a multiple pregnancy you add the 500 calories and 25 grams protein for each fetus.
What is interesting about the Higgins Intervention Method, is that it also changes based on other characteristics of the mother. If the mother was more than 5% under weight, she adds an additional 500 calories and 20 grams per day. If she has nutritional stress such as close pregnancy spacing or pernicious vomiting, she adds 200 calories and 20 grams of protein for each stress inducing condition.