The optimal weight gain during pregnancy is of great interest to the majority of pregnant patients and is associated with favorable birth outcomes. For nearly a decade, recommendations endorsed by the Institute of Medicine, American Academy of Pediatrics and American College of Obstetricians and Gynecologists have been based on the prepregnancy body mass index (BMI). Women with a BMI below 19.8 kg per m² are recommended to gain 12.7 to 18.2 kg (28 to 40 lb), women with a BMI of 19.8 to 26.0 kg per m² are advised to gain between 11.4 and 16.0 kg (25 to 35 lb), and women with a high BMI (26.0 to 29.0 kg per m²) are recommended to gain between 6.8 and 9.1 kg (15 to 20 lb). Women who have a very high BMI (above 29 kg per m²) are advised to gain at least 6.8 kg (15 lb). Cogswell and colleagues studied the use of these guidelines in practice and the influence that advice from health professionals had on actual weight gain during pregnancy.

Data were obtained through a postal survey sent to more than 3,000 households into which an infant was born during 1993. Approximately 2,300 women completed a prenatal questionnaire that included prepregnancy weight, height, the weight gain advised by health professionals and the woman's personal target weight gain during pregnancy. Women who delivered a singleton infant weighing more than 2.3 kg (5 lb) were invited to complete a neonatal questionnaire concerning actual weight gain during pregnancy. Other data gathered included race, age, educational level, marital status, parity, gestation at entry into prenatal care, household income and participation in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) program.

Overall, 27 percent of women reported receiving no advice about weight gain during pregnancy. Of this percentage, a greater number of women were more than 35 years of age, had a parity of at least one and did not participate in WIC. Women who had not been advised about weight gain were more likely to gain outside the recommended ranges. Of the 1,643 women who recalled weight gain advice, 14 percent reported being advised to gain less than the recommended levels, and 22 percent were advised to gain more. Women who had high BMIs were most likely to report being advised to gain more weight than the recommended level. Women who were black, had late entry into prenatal care and participated in WIC were more likely to be advised to gain less weight than the recommended level. Women's personal target weight gains corresponded closely to the advice given. Women who were advised to gain more than the recommended level were 3.6 times more likely to do so than women who were advised to gain weight within the recommended range. Similarly, women who were given low weight-gain recommendations were 3.6 times more likely to gain less than the recommended weight than women who had been given accurate recommendations. Overall, 23 percent of all women actually gained less and 42 percent gained more than the recommended range.

The authors conclude that almost one half of the women in this study reported receiving no advice or inappropriate advice from health professionals regarding weight gain during pregnancy. Women at high risk of adverse outcome because of high BMI or race appear to be the ones least likely to receive appropriate advice. The authors recommend that physicians make greater efforts to improve advice to women about appropriate weight gain during pregnancy.

editor's note: Instinctively, one believes these results apply to other physicians' patients or must be due to faulty recall by the women. Advice about weight gain is an obvious and routine part of good pregnancy care, so why did one half of women in this study report receiving erroneous advice or no advice at all? Certainly part of the answer is in patient recall, but even this points to communication of such low impact that it was repressed or forgotten. Perhaps it is time to see that advice about weight gain be included as a specific item on our prenatal checklist and that the advice we give is accurate. This is especially important in women already at risk of delivering a small baby (e.g., black women) and women at risk of macrosomia because of obesity. The good news from this study is that women seem to be influenced by professional advice in the weight gain they believe is appropriate and the weight gain they actually achieve.—a.d.w.