Chapter One: Heavy Issues Many people believe that pregnancy contributes to obesity. However, research shows that women who gain as recommended while they are pregnant have no greater reason to fear a permanent battle with obesity than nonpregnant women of the same age. Instead, pregnant women should take comfort in knowing that by gaining that recommended 25 to 35 pounds they have made an important contribution to the health of their baby.
HOW MUCH WEIGHT
The current weight gain recommendations for women of normal weight during pregnancy are at a higher level than they have been in the past 20 to 30 years. In the 1960s, the typical expectant mother was told to limit her weight gain to 15 to 20 pounds. She was even encouraged to use appetite suppressants and low-calorie diets to limit her weight gain, thereby preventing weight-related health problems and making her delivery easier. In the 1970s, researchers saw a connection between low weight gain and the birth of preterm, low-birth-weight babies. As a result, the 1970s mom was told to gain 20 to 25 pounds. In the 1980s researchers saw a 20 percent reduction in low-birthweight babies among white mothers and a 7 percent reduction among black mothers who gained eight to ten pounds more than their 1970s counter-parts. As a result, weight-gain recommendations were increased even further. Today, the Institute of Medicine (IOM) offers a general weight-gain recommendation during pregnancy of 25 to 35 pounds, plus three different weight-gain guidelines based on a woman's weight for height before conception.
Weight-gain ranges are based on prepregnancy body mass index (BMI). BMI is defined as body weight divided by height squared, and it is considered a better indicator of nutritional status than weight alone. Use your prepregnancy weight to calculate your BMI with the help of the chart on page 3. Once you determine your prepregnancy BMI, select the interpretation that describes you: underweight, normal, overweight, or obese. A 5'8" woman weighing 140 pounds at conception has a "normal" BMI of 21.5. A 5'8" woman weighing 120 pounds, with a BMI of less than 19 is described as "underweight." Once your BMI is determined, select the recommended weight gain that matches your description.
HOW FAST SHOULD I GAIN?
Your doctor will weigh you at every visit. Some women hate these weight checks and feel they are the doctor's way of checking up on them to see whether they have been "good" or "bad." The truth is that your doctor is checking up on you, but only to look for signs of good or bad health. Weight can be a very effective tool when evaluating the progress of a pregnancy.
A gradual, steady weight gain is ideal. In the first 13 weeks most obstetricians like to see a weight gain of two to five pounds, followed by a steady increase of approximately one pound per week until delivery. A gradual gain in weight suggests that both lean and fat tissue are being added, whereas an erratic and sudden increase can indicate a dangerous problem, such as the retention of fluid that is one of the symptoms of preeclampsia.
Though the ideal might be a nice, steady, even weight gain, in reality most women will not gain weight in such a uniform manner. The British Journal of Obstetrics and Gynecology published a 1991 study that took a retrospective look at how mothers with a normal pregnancy outcome gain weight, and found that there was a wide variation in weight gain over the course of pregnancy. The slowest weight gain occurred before 16 weeks, after 35 weeks, and right before the eighth month between week 28 and week 32. The differences in average weekly weight gain among the mothers studied were related to number of pregnancies, BMI, smoking habits, and history of high blood pressure.
Many things can make it difficult to interpret weight gain. If the date of conception is uncertain, it is difficult to assess weight-gain patterns. In some cases, an unexpected weight gain can be related to how much food or liquid was consumed before a weight check. Whether a mother has a full or empty bladder or has had a bowel movement will affect the recorded weight. Even clothing and time of day affect weight measurements. The point is, a jump in weight does not always mean you ate too much or that something is wrong. In some cases it is a fluke in the weighing technique. As always, talk to your health-care provider and focus on the trend in weight gain, not just one reading.
To help practitioners and women make sense of what is considered a healthy weight-gain trend, the IOM has suggested recommended weight-gain patterns. With the help of your doctor, use these to establish a weight-gain goal that is right for you.
Adolescent women need to aim for the high end of the recommended weight ranges, and women under 5'2" should attempt to keep to the lower end. Women who are carrying twins may be advised to gain 35 to 45 pounds. The IOM suggests that women of normal weight who gain less that two pounds per month should investigate the reasons for slow weight gain with their doctor. And women who do not gain at least ten pounds by midpregnancy need to receive nutrition counselling. Gains of over six and a half pounds per month may need to be monitored, but food intake should not automatically be reduced. Weight gain continues to be important until the end of pregnancy. For instance, a low weight gain in normal-weight women in the last three months of pregnancy may be a cause of early delivery.
Is gaining above the recommended weight-gain levels even better for baby? The answer is, probably not. In a study of over 53,000 infants it was found that low birth weight decreased with increasing weight gain in average-weight women, but there was no further reduction in low birth weight when weight gains were higher than 30 to 40 pounds. Women with high weight gains are at increased risk for high-birth-weight babies, which can make delivery difficult. If you have a BMI higher than 29 you may be advised by your doctor to limit your weight gain to 15 to 25 pounds. (Some physicians may recommend an even lower weight gain based on a woman's medical history.) A lower weight gain may reduce an overweight woman's risk for a high-birth-weight infant.
AFTER DELIVERY
No one can predict exactly how any individual woman will gain or lose weight but a review of the research can give mothers some reassuring news. In 1993, Sally Ann Lederman, Ph.D., then of Columbia University's School of Public Health, reviewed the pregnancy-related research to determine whether one's weight increases permanently as a result of pregnancy. The studies showed that the average woman generally retains less than three pounds of added weight (from before pregnancy to one year after delivery). A small number of women may retain a lot of their pregnancy weight, but this is more likely due to having been overweight at conception and to lifestyle changes rather than to pregnancy itself. The woman who begins her pregnancy overweight may be at greater risk for being heavier after delivery.
A study of 1,423 Swedish mothers who averaged the recommended 30-pound gain during pregnancy found that the average weight gain was only three pounds one year after delivery. In another study the weight-gain patterns of 795 American women who gained approximately 28 pounds during pregnancy were examined. It was found that they averaged only three pounds above their initial weight at their six-month postpartum visit. This research suggests that for an average-weight woman, weight retention related to pregnancy is about three pounds, six months to one year after delivery. It is important to note that there are big differences among the women in these studies. In the Swedish study, for example, 2 percent of the mothers gained 20 pounds from before pregnancy to one year after delivery. The women gaining the most weight tended to be overweight to begin with.
Being Overweight Before Pregnancy
Women who are overweight before pregnancy can benefit by setting weight-gain goals for their pregnancy with their doctor. In a study that looked back on the weight gains of 128 severely obese women, more than 70 percent of these mothers had retained over 20 pounds one year after delivery. This suggests that for the very overweight woman, pregnancy can contribute significantly to weight. In another study at the University of Utah the weight histories of 96 very obese mothers were compared to 115 non-obese women. It was observed that the obese mothers had gained 100 pounds by age 46 and the control group 31 pounds. The obese women retained more weight after their first pregnancy than the control group, and the obese women lost less weight after delivery and had greater gains between pregnancies than did the control group. (It may be that women who end up obese increase weight gradually over 20 years and some of that time pregnancy is happening.)
Women who gain excessive weight during pregnancy may increase their chance of induced labor and risk for an emergency cesarean section. Research suggests that obese women are more likely to have large babies no matter what their weight gain.
If you are overweight before pregnancy you may be at greater risk for retaining weight postpartum. With the help of your medical team, develop a weight-gain goal while pregnant and a weight-loss plan following delivery. The woman who begins her pregnancy overweight is at the greatest risk for being even heavier after delivery and will benefit most by considering her food selections very carefully.
Aging
For most women it is not pregnancy that is the cause of weight gain, but rather the fact they are getting older. In a study of over 41,184 postmenopausal women, even the women who had no children gained a significant amount of weight between ages 18 and 50. In this study, the difference in weight between women who had no children and those who had one to four children was small. In a large Finnish study that compared the weight of women with and without children, women who were over 35 an...
