Current and future impact of rising multiple birth ratios on low birthweight

Multiple births are affecting the overall rate of low birthweight. Multiple birth ratio among white women increased from 1980 to 1992. At the same time, overall low birthweight increased despite the fact that low birthweight for singletons declined. This could only mean that the increased low birthweight is primarily caused by higher multiple birth rates. Increased multiple births among blacks, meanwhile, corresponded with increased low birthweights. Although low birthweights also increased among black singletons, the rate was much higher among multiple births.
Following declines in the 1970s and early 1980s, low birthweight(*) levels deteriorated in the United States. The proportions rose from 6.8 percent in 1982 to 7.1 in 1992 for all [...]