Measuring adequacy of prenatal care: does missing visit information matter?

Kotelchuck's Adequacy of Prenatal Care Utilization (APNCU) Index is frequently used to classify levels of prenatal care. In the Finger Lakes Region (FLR) of upstate New York, prenatal care visit information late in pregnancy is often not documented on the birth certificate. We studied the extent of this missing information and its impact on the validity of regional APNCU scores.

We calculated the "weeks between" a mother's last prenatal care visit and her infant's date of birth. We adjusted the APNCU algorithm creating the Last Visit Adequacy of Prenatal Care (LV-APNC) Index using the last recorded prenatal care visit date as the end point of care and the expected number of visits at that time. We compared maternal characteristics by care level with each index, examining rates of reclassification and number of "weeks between" by birth hospital. Stuart-Maxwell, McNemar, chi-square, and t-tests were used to determine statistical significance.

Based on 58,462 births, the mean "weeks between" was 2.8 weeks. Compared with their APNCU Index score, 42.4 percent of mothers were reclassified using the LV-APNC Index. Major movement occurred from Intermediate (APNCU) to Adequate or Adequate Plus (LV-APNC) leaving the Intermediate Care group a more at-risk group of mothers. Those with Adequate or Adequate Plus Care (LV-APNC) increased by 31.6 percent, surpassing the Healthy People 2020 objective.

In the FLR, missing visit information at the end of pregnancy results in an underestimation of mothers' prenatal care. Future research is needed to determine the extent of this missing visit information on the national level.