Table 3.
Maternal mortality ratios per 100,000 live births (MMRs) and crude and adjusted maternal mortality rate ratios, United States, 1993 to 2014.
| Year | Maternal mortality ratio | Unadjusted
|
Adjusted*
|
||||
|---|---|---|---|---|---|---|---|
| Rate Ratio | 95%confidence interval | P value | Rate ratio | 95% confidence interval | P value | ||
| Separate question | - | 0.71 | 0.65–0.78 | <0.001 | 1.09 | 1.00–1.19 | 0.05 |
| ICD-10 coding | - | 1.92 | 1.74–2.12 | <0.001 | 1.75 | 1.37–2.23 | <0.001 |
| Checkbox | - | 2.12 | 1.99–2.27 | <0.001 | 1.73 | 1.56–1.92 | <0.001 |
| 1993 | 7.55 | 1.00 | Reference | Reference | 1.00 | Reference | Reference |
| 1994 | 8.28 | 1.10 | 0.83–1.46 | 0.50 | 1.10 | 0.84–1.44 | 0.49 |
| 1995 | 7.10 | 0.94 | 0.70–1.27 | 0.69 | 0.94 | 0.71–1.25 | 0.69 |
| 1996 | 7.63 | 1.01 | 0.76–1.35 | 0.92 | 1.01 | 0.77–1.33 | 0.93 |
| 1997 | 8.43 | 1.12 | 0.84–1.48 | 0.42 | 1.12 | 0.85–1.46 | 0.42 |
| 1998 | 7.13 | 0.95 | 0.71–1.27 | 0.71 | 0.94 | 0.72–1.25 | 0.69 |
| 1999 | 9.88 | 1.31 | 1.00–1.72 | 0.02 | 0.75 | 0.60–0.94 | 0.01 |
| 2000 | 9.76 | 1.30 | 0.99–1.70 | 0.05 | 0.74 | 0.59–0.93 | 0.008 |
| 2001 | 9.91 | 1.32 | 1.01–1.72 | 0.02 | 0.75 | 0.60–0.94 | 0.01 |
| 2002 | 8.88 | 1.18 | 0.90–1.55 | 0.10 | 0.67 | 0.53–0.85 | 0.001 |
| 2003 | 12.1 | 1.61 | 1.24–2.08 | <0.001 | 0.79 | 0.65–0.97 | 0.02 |
| 2004 | 13.1 | 1.75 | 1.35–2.25 | <0.001 | 0.83 | 0.68–1.00 | 0.05 |
| 2005 | 15.1 | 2.00 | 1.56–2.56 | <0.001 | 0.90 | 0.75–1.07 | 0.23 |
| 2006 | 13.3 | 1.77 | 1.38–2.28 | <0.001 | 0.75 | 0.63–0.90 | 0.002 |
| 2007 | 12.7 | 1.69 | 1.31–2.17 | <0.001 | 0.70 | 0.58–0.84 | <0.001 |
| 2008 | 15.5 | 2.06 | 1.62–2.64 | <0.001 | 0.81 | 0.68–0.97 | 0.02 |
| 2009 | 16.6 | 2.20 | 1.73–2.81 | <0.001 | 0.87 | 0.73–1.03 | 0.10 |
| 2010 | 16.9 | 2.24 | 1.75–2.86 | <0.001 | 0.86 | 0.72–1.02 | 0.08 |
| 2011 | 19.3 | 2.57 | 2.02–3.27 | <0.001 | 0.98 | 0.82–1.15 | 0.77 |
| 2012 | 19.9 | 2.65 | 2.08–3.36 | <0.001 | 0.97 | 0.82–1.14 | 0.70 |
| 2013 | 22.0 | 2.92 | 2.31–3.70 | <0.001 | 1.06 | 0.90–1.25 | 0.48 |
| 2014 | 21.5 | 2.82 | 2.25–3.61 | <0.001 | -† | -† | -† |
Maternal mortality ratios do not include late maternal deaths.
Adjusted for a separate pregnancy question on death certificates, International Statistical Classification of Diseases and Related Health Problems (ICD-10) coding, and the standard pregnancy checkbox on death certificates.
Indicator variable for the year 2014 aliased as it was a linear combination of the other variables (collinearity). The regression equation is: Log P(maternal death) = −9.5306+(0.0946*v1994)+( −0.0575*v1995) +(0.0116*v1996)+(0.1105*v1997)+( −0.0566*v1998)+( −0.2895*v1999)+( −0.3015*v2000) +(−0.2875*v2001)+( −0.3976*v2002)+( −0.2340*v2003)+( −0.1911*v2004)+( −0.1108*v2005) +(−0.2859*v2006)+( −0.3548*v2007)+( −0.2083*v2008)+( −0.1430*v2009)+( −0.1527*v2010) +(−0.0250*v2011)+( −0.0329*v2012)+(0.0580*v2013)+(0.0873*Separate question)+(0.5577*ICD10) +(0.5480*Standard checkbox).