black women retain more weight than white or Hispanic women regardless of their prepregnancy weight or GWG category. Compared with women in IFPS II, which is a higher income sample, the low-income women in PNSS retained more weight.
The committee examined trends since 1990 in several weight-related sociodemographic and lifestyle characteristics of pregnant women, in an effort to identify trends related to GWG and to provide information that may be helpful in developing interventions aimed at increasing the number of women that gain within the recommended ranges.
Since 1990 there have been several changes in the sociodemographic characteristics of women, as shown in Table 2-5:
Between 1990 and 2005, there was an increase in the racial and ethnic diversity of U.S. births with a greater proportion of infants in 2005 born to nonwhite mothers, with the largest increase in births from Hispanic mothers.
Childbearing by unmarried mothers sharply increased in this 15-year period to a record high of 36.9 percent.
More mothers attained high levels of education; in 2005, more than one-quarter of mothers had 16 years or more of education.
The proportion of births for mothers 35 years and older also increased substantially during this period.
Although the teenage birth rate had been steadily declining since 1991, preliminary data from 2006 suggest that the birth rate for teenagers 15-19 years of age rose 3 percent to 41.9 births per 1,000 females. Teenage females 10-14 years of age were the only group that did not experience an increase in birth rate during this time.
Finally, the proportion of mothers who reported any smoking during pregnancy declined by about 50 percent over the rates reported prior to 1990 (CDC, 2004).
The following discussion summarizes the committee’s evaluation of key weight-related lifestyle characteristics that may affect GWG, including dietary practices (dietary intake, dieting, food insecurity), physical activity, and psychological characteristics.