THE CHANGING PATTERN OF PRENATAL-CARE UTILIZATION IN THE UNITED-STATES, 1981-1995, USING DIFFERENT PRENATAL-CARE INDEXES

Context.-Two measures traditionally used to examine adequacy of prenat al care indicate that prenatal care utilization remained unchanged thr ough the 1980s and only began to rise slightly in the 1990s. In recent years, new measures have been developed that include a category for w omen who receive more than the recommended amount of care (intensive u tilization). Objective.-To compare the older and newer indices in the monitoring of prenatal care trends in the United States from 1981 to 1 995, for the overall population and for selected subpopulations. Secon d, to examine factors associated with receiving intensive utilization. Design.-Cross-sectional and trend analysis of national birth records. Setting.-The United States. Subjects.-All live births between 1981 an d 1995 (N=54 million). Main Outcome Measures.-Trends in prenatal care utilization, according to 4 indices (the older indices: the Institute of Medicine Index and the trimester that care began, and the newer ind ices: the R-GINDEX and the Adequacy of Prenatal Care Utilization Index ). Multiple logistic regression was used to assess the risk of intensi ve prenatal care use in 1981 and 1995. Results.-The newer indices show ed a steadily increasing trend toward more prenatal care use throughou t the study period (R-GINDEX, intensive or adequate use, 32.7% in 1981 to 47.1% in 1995; the Adequacy of Prenatal Care Utilization Index, in tensive use, 18.4% in 1981 to 28.8% in 1995), especially for intensive utilization. Women having a multiple birth were much more likely to h ave had intensive utilization in 1995 compared with 1981 (R-GINDEX, 22 .8% vs 8.5%). Teenagers were more likely to begin care later than adul ts, but similar proportions of teens and adults had intensive utilizat ion. Intensive use among low-risk women also increased steadily each y ear. Factors associated with a greater likelihood of receiving intensi ve use in 1981 and 1995 were having a multiple birth, primiparity, bei ng married, and maternal age of 35 years or older. Conclusions.-The pr oportion of women who began care early and received at least the recom mended number of visits increased between 1981 and 1995. This change w as undetected by more traditional prenatal care indices. These increas es have cost and practice implications and suggest a paradox since pre vious studies have shown that rates of preterm delivery and low birth weight did not improve during this time.