Weight Gain During Pregnancy: Trends and Outcomes. (continued on next page).
During the 20th century, recommendations for appropriate weight gain in ...
FOCUS A PUBLICATION OF THE MISSOURI DEPARTMENT OF HEALTH & SENIOR SERVICES BUREAU OF HEALTH INFORMATICS JEFFERSON CITY, MISSOURI 65102-0570 (573) 751-6272 January 2011
Weight Gain During Pregnancy: Trends and Outcomes During the 20th century, recommendations for appropriate weight gain in pregnancy changed dramatically, ranging from rigid restriction in the first half of the century to substantial gain in the 1970s and 1980s1. In 1990, the Institute of Medicine (IOM) recommended weight gain ranges with the primary goal of improving infant birth weight. Based on prepregnancy body mass index (BMI) categorizations, the recommended weight gain ranges were: 28-40 pounds for underweight women, 25-35 pounds for normal weight women, 15-25 pounds for overweight women and at least 15 pounds for obese women. The recommendation for obese women was modified in 2009 to 11-20 pounds. In addition, the BMI ranges were slightly changed in 2009 to conform to those used by the World Health Organization rather than those developed from the Metropolitan Life Insurance tables.
linked to weight gain, only singleton full-term (at least 37 weeks gestation) births were included in the analysis.
This report examines the trends in weight gain during pregnancy among Missouri women from 1989 to 2008 as well as the pregnancy outcomes by weight gain among Missouri women for the five year period 20042008. The 2009 IOM ranges of recommended weight gain were used as one set of categories for measuring adequacy of weight gain. Low was defined as less than the lower limit of the recommended range for each prepregnancy BMI group. Normal was defined as within the recommended range, while high was above the highest limit of the range. In addition, the data are also presented using the simpler categorization of less than 15 pounds, 15-44 pounds and 45 or more pounds gain. These categories have been used in numerous previous annual vital statistics and website reports by the Missouri Department of Health and Senior Services. Because multiple births and gestational age are strongly
According to the 2009 IOM guidelines, less than one -third of Missouri mothers in 2008 gained the recommended amount of weight during pregnancy. About 52 percent gained too much weight and 15 percent gained too little weight. The comparable percents in 1989 were about 40 percent normal weight gain, 40 percent high and 20 percent low. These percentages varied tremendously by pre-pregnancy BMI category. In 2008 the proportion with high weight gain ranged from 26.8 percent for underweight women to 68.1 percent for overweight women. Comparable percentages for normal weight women and obese women were 43.2 and 58.1 percent, respectively. Overweight women gained an average of 2 pounds less than underweight and normal weight women, but the IOM recommends they gain at least 10 pounds less based on a comparison of the recommended ranges.
As Table 1 shows, weight gain has been edging upwards among Missouri mothers over the last nearly 20 years. The average weight gain in 1989 was 31.6 pounds compared to 32.5 pounds in 2008. Those gaining 45 or more pounds increased from 14.2 percent of births in 1989 to 18.8 percent in 2008. The weight gain increase would have been greater if not for the increase in the proportion of women in higher BMI categories. The number and percent of obese women more than doubled from 1989 to 2008. Generally, and as the IOM recommends, heavier women do not gain as much weight as normal weight women. In 2008, obese mothers gained about 10 pounds less during pregnancy than normal weight and underweight mothers.
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Table 1 Trends in Percent Distributions of Weight Gain During Pregnancy by Pre-pregnancy BMI Category: Missouri Resident Singleton Full-term Births 1989, 1993, 1998, 2003, and 2008 Total
Weight Gain Based on IOM* Guidelines Low Normal High 20.1 40.2 39.7 18.2 37.3 44.5 16.0 35.0 48.8 14.7 33.1 52.2 15.4 32.6 52.0
Births Avg.(lbs) 65,118 31.6 62,556 32.0 62,197 32.5 62,282 33.0 64,728 32.5
< 15 lbs 5.9 7.1 7.8 8.3 9.1
15-44 lbs 79.9 77.0 74.6 72.0 72.1
45+ lbs 14.2 16.0 17.6 19.7 18.8
1989 1993 1998 2003 2008
Births Avg.(lbs) 5,831 32.5 4,552 33.3 3,747 35.2 3,231 36.4 3,001 35.3
< 15 lbs 2.1 2.2 2.2 1.4 1.9
15-44 lbs 84.3 82.6 77.2 75.9 78.9
45+ lbs 13.6 15.1 20.6 22.7 19.2
Low 34.8 32.3 25.7 22.2 25.9
Normal 45.7 46.0 46.9 47.1 47.4
High 19.5 21.6 27.4 30.6 26.8
1989 1993 1998 2003 2008
Births Avg.(lbs) 41,892 32.7 37,175 33.7 33,549 34.7 31,340 35.7 31,078 35.3
< 15 lbs 2.8 2.9 2.6 2.4 2.7
15-44 lbs 82.8 80.4 78.2 75.7 76.4
45+ lbs 14.5 16.7 19.2 21.9 20.9
Low 21.5 19.7 17.5 15.8 16.9
Normal 44.7 42.4 41.5 40.1 39.9
High 33.8 37.9 41.0 44.1 43.2
1989 1993 1998 2003 2008
Births Avg.(lbs) 10,564 31.0 11,936 31.4 13,478 32.0 14,342 33.1 15,439 33.0
< 15 lbs 8.4 8.4 8.4 7.5 7.7
15-44 lbs 76.4 74.7 74.0 72.0 72.4
45+ lbs 15.3 16.8 17.6 20.5 19.9
Low 8.4 8.4 8.4 7.5 7.7
Normal 29.3 27.6 25.7 24.2 24.2
High 62.3 64.0 65.9 68.4 68.1
1989 1993 1998 2003 2008
Births Avg.(lbs) 6,562 24.7 8,517 24.8 11,031 25.1 13,012 25.5 14,735 25.6
< 15 lbs 24.4 25.0 24.1 24.8 24.6
15-44 lbs 66.4 64.7 65.2 63.5 63.3
45+ lbs 9.3 10.4 10.7 11.7 12.1
Low 16.6 17.5 17.3 18.1 17.7
Normal 26.1 25.4 24.5 23.3 24.2
High 57.3 57.1 58.2 58.6 58.1
1989 1993 1998 2003 2008 Underweight
Normal
Overweight
Obese
*Institute of Medicine
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As Table 2 shows, African-American mothers tended to gain excess weight and too little weight more than white women, although the differences were not substantial. Younger mothers tended to gain more weight during pregnancy than their older counterparts, even after adjusting for BMI. Similarly, unmarried mothers and women having their first birth also had higher rates of
excess weight gain during pregnancy. Among those with higher rates of gaining less weight than the IOM guidelines were women of other races (neither white nor black), women aged 35 or more, women having higher order births, underweight women, smokers, and those having inadequate prenatal care.
Table 2 Percent Distribution of Weight Gain During Pregnancy by Selected Variables: Missouri 2004-2008 Resident Singleton Full-term Births Number of Births
Percent Gain
