March of Dimes March of Dimes Peristats

Calculations

Maternal Mortality

Maternal Mortality

Maternal death is defined as one that occurs during pregnancy or within 42 days of the end of a pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by a woman's pregnancy, but not from accidental or incidental cause. Maternal mortality rates are calculated as the number of maternal deaths in a calendar year divided by the number of live births for the same period, multiplied by 100,000. The number of live births used in the denominator is an approximation of the population of pregnant women who are at risk of a maternal death. The numerator is calculated using data from the Final Mortality File from NCHS, included in these deaths assigned an underlying cause of death ICD-10 code of A34, O00-O95, or O98-O99. The denominator is calculated using data from the Natality File from NCHS.

Impact of Death Certificate Revision on Maternal Mortality Rates

The 2003 revision of the U.S. Standard Certificate of Death introduced a standard question format for maternal deaths and a separate pregnancy status item on the death certificate resulted in the identification of more maternal death. Therefore data beginning in 2003 may not be comparable to previous years.(1) To date the following states on the PeriStats web site have implemented the 2003 revision:

  • 2003: CA, ID, MT, NY
  • 2004: MI, NJ, OK, SD, WA, WY
  • 2005: CT, FL, KS, NE, NH, SC, UT
  • 2006: NM, OR, RI, TX, DC
  • 2007: DE, OH

This section of the web site will be updated as additional states implement the 2003 U.S. Standard Certificate of Death.

1. Hoyert DL, Heron MP, Murphy SL, Kung H. Deaths: Final Data for 2003. National vital statistics reports; vol 54 no 13. Hyattsville, MD: National Center for Health Statistics. 2006.