Recent Increases in the U.S. Maternal Mortality Rate: Disentangling Trends From Measurement Issues

Abstract

Objective: To develop methods for trend analysis of vital statistics maternal mortality data, taking into account changes in pregnancy question formats over time and between states, and to provide an overview of U.S. maternal mortality trends from 2000 to 2014.

Methods: This observational study analyzed vital statistics maternal mortality data from all U.S. states in relation to the format and year of adoption of the pregnancy question. Correction factors were developed to adjust data from before the standard pregnancy question was adopted to promote accurate trend analysis. Joinpoint regression was used to analyze trends for groups of states with similar pregnancy questions.

Results: The estimated maternal mortality rate (per 100,000 live births) for 48 states and Washington, DC (excluding California and Texas, analyzed separately) increased by 26.6%, from 18.8 in 2000 to 23.8 in 2014. California showed a declining trend, whereas Texas had a sudden increase in 2011-2012. Analysis of the measurement change suggests that U.S. rates in the early 2000s were higher than previously reported.

Conclusion: Despite the United Nations Millennium Development Goal for a 75% reduction in maternal mortality by 2015, the estimated maternal mortality rate for 48 states and Washington, DC, increased from 2000 to 2014; the international trend was in the opposite direction. There is a need to redouble efforts to prevent maternal deaths and improve maternity care for the 4 million U.S. women giving birth each year.

Figure 1

Adjusted Maternal Mortality Rates, Analysis Group 1, 2000–2014. Note: Includes 24 states and Washington D.C. that did not have a pregnancy question on their unrevised death certificate and that adopted the U.S. standard question upon revision: Arkansas, Arizona, Connecticut, Delaware, Georgia, Idaho, Kansas, Maine, Michigan, Montana, New Hampshire, Nevada, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Utah, Vermont, Washington, and Wyoming.

Figure 2

Adjusted Maternal Mortality Rates, Analysis Group 2, 2000–2014. Note: Includes 13 states that had a pregnancy question asking about a longer timeframe on their unrevised death certificate and that adopted the U.S. standard question upon revision: Florida, Illinois, Indiana, Idaho, Kentucky, Louisiana, Mississippi, Minnesota, Missouri, Nebraska, New Jersey, New York, and North Dakota.

Figure 3

Unadjusted Maternal Mortality Rates, Analysis Groups 3 and 4, 2000–2014. Note: Group 3 includes 8 states that did not have a pregnancy question on their unrevised death certificate (Alaska, Colorado, Hawaii, North Carolina, Massachusetts, West Virginia, and Wisconsin) or that had a pregnancy question with a longer timeframe (Virginia) and had not revised as of late 2013 (Wisconsin revised in late 2013 and their data were excluded from the 2013 data point). Group 4 includes 3 states (Alabama, Maryland, and New Mexico) that had an unrevised pregnancy question consistent with the U.S. standard.

Figure 4

Adjusted Maternal Mortality Rates, Texas, 2000–2014 Note: Texas revised to the U.S. standard pregnancy question in 2006. The unrevised question asked about pregnancies within the past 12 months.

Figure 5

Unadjusted Combined Maternal and Late Maternal Mortality Rates, California, 2000–2014. Note: Includes pregnancy-related deaths occurring within 1 year of pregnancy. California revised their death certificate in 2003 to a non-standard question that asks about deaths within 1 year of pregnancy. Prior to 2003, California did not have a pregnancy question on their death certificate.