age group (Figure 2-18), with the largest increase over time among women in the oldest age group (40 years or more). However, the majority of birth certificates did not distinguish between pre-gestational diabetes (diagnosis before the index pregnancy) and gestational diabetes mellitus (GDM; diagnosis during the index pregnancy).
Using data from the National Hospital Discharge Survey from 1989 to 2004, Getahun et al. (2008) determined trends in the prevalence of GDM among U.S. women 14 to 45 years of age. GDM increased by 122 percent, from 1.9 percent in 1989-1990 to 4.2 percent in 2003-2004. Among women 35 years of age and older, the rate for GDM was highest among black women.
Wallis et al. (2008) investigated population trends in the incidence rates of pregnancy-induced hypertension (preeclampsia and gestational hypertension [see Appendix A for definitions]) in the United States for 1987-2004 using data from the National Hospital Discharge Survey. The age-adjusted rate of preeclampsia increased 25 percent from 1987-1988 to 2003-2004. Gestational hypertension rates nearly tripled during the same period (Figure 2-19). The authors noted that clinical diagnostic criteria, revised in the 1990s, may have simultaneously caused an exaggerated rise in the rate of gestational hypertension and an attenuated increase in the rate