As Mum Mum’s recently reported, being obese at time of conception may increase the risk of obesity for the baby later in life. As much more research is finding adverse effects of high maternal weights, the next logical question is: so how much weight does a woman need to gain during pregnancy if she is overweight? A recent study looked into that question directly.
The Institute of Medicine released new guidelines for pregnancy weight gain in 2009 to account for the changes in population; particularly the number of women who are obese and 
overweight at childbearing age. The new study reveals that even the current recommended weight gain amounts may be more than necessary for obese women.
In an attempt to determine the impact of weight gain outside the recommended guidelines in the second and third trimesters, researchers grouped 73,977 women who gave birth to babies in the Finger Lakes area of New York between 2004 and 2008 by pre-pregnancy BMI (body mass index). The categories included women who were underweight, normal weight, overweight, and obese classes I, II, and III. Obese classes II and III included women who were severely and morbidly obese.
Gaining less weight than recommended is associated with giving birth to a low birth weight baby in all BMI groups except classes II and III. Conversely, gaining more than the recommended amount of weight is associated with an increased likelihood of having a baby who is large for gestational age in all groups. Baby’s weight at birth, either too little or too much, can present health risks at delivery and later on. The key finding of study, however, was that severely obese women who gained less than the recommended amount of weight during pregnancy incurred no ill effects to themselves or their babies. Yet normal weight and obese women who gained less than the recommended amount of weight were more likely to have a baby that was small for gestational age.
What This Means for Mums
Although most of our readers are mums, perhaps you may be wondering where this information was when you were pregnant but it could bear some significance if you are planning to have more children; especially if you are still carrying extra weight from previous pregnancies. A BMI greater than 30 is classified as obese, and the class II and III are greater than 34 and 40 respectively. Although BMI is not an absolute indicator of ‘health’ as it doesn’t account for body composition (muscle tissue vs. fat) it remains the most commonly used system of weight classification so your health care practioner is likely to calculate your BMI.
With pregnancy, it most important that mums get the nutrients they need to support their growing fetus. Severe dietary restrictions are not recommended but perhaps our old mentality of eat whatever you want as much as you want needs a little updating. Yet pregnancy is also NOT the time to go on a diet because as this study explains gaining too little weight also poses health risks. The key take away of this study is that women need to be thinking about their health before getting pregnant. If you are thinking of having a baby in the future, this would be a good time to tackle those lifestyle changes you may have been putting off. Taking good care of yourself now can help your baby in the future. As always, discuss this topic with your physician and make sure you are getting regular checkups throughout your pregnancy.
Tags: BMI, pregnancy weight gain
