Previous research suggests that timely delivery of appropriate healthcare services may prevent almost half of all pregnancy-related deaths in the United States. Although maternal deaths are increasingly attributed to preexisting conditions, the relative effect of these conditions and the extent to which maternal morbidity and mortality are concentrated in high-risk patients have not been well defined.
Focusing on Near-Miss Pregnancy Events
Jill M. Mhyre, MD, and colleagues had a study published in the November 2011 issue of Anesthesiology that sought to identify which preexisting conditions predicted maternal morbidity, mortality, and “near- miss” events. A near miss occurs when pregnant women or recently postpartum women survive a life-threatening event, either because of high-quality medical care or by chance alone. “In our study, we investigated women who died as well as those who survived an event in the hopes of uncovering important lessons with regard to predicting outcomes and preventing progression from near misses to death,” says Dr. Mhyre. A near miss was defined as end-organ injury that impacted hospital discharge.
The highest rates of near-miss morbidity or mortality events were found among women with pulmonary hypertension (PH), malignancy, and systemic lupus erythematosus (Table). Advancing maternal age and non-white race also increased risk for near-miss morbidity or mortality. “While the effect sizes we observed for age and race were relatively modest when compared with certain medical conditions, these effects remained statistically significant even after controlling for all other medical and obstetric conditions,” Dr. Mhyre says. “The absolute rate per thousand deliveries increased three-fold when age older than 40 was compared with ages 20 to 34, but the adjusted odds ratio was only two-fold. This finding suggests the absolute increase is driven largely by coexisting medical conditions.” When compared with white women, all other races had higher adjusted odds ratios for near misses or maternal death, with African Americans faring the worst.
Examining Pregnancy Risk Thresholds
The study by Dr. Mhyre and colleagues also defined thresholds for risk in their research. The majority of near-miss events (58%) occurred in less than 12% of the delivering population. “The sensitivity and specificity of these predictors appeared to be poor when compared with desired values for diagnostic tests, but we were predicting a rare outcome,” explains Dr. Mhyre. “Just one in 760 women experienced a near-miss morbidity or mortality event.”
According to the data, women with pulmonary hypertension or malignancy faced a substantially increased risk when compared with women without either condition. In contrast, one in nearly 2,000 women without a medical condition listed in the Table (right) experienced a near-miss morbidity or mortality event during hospitalization for delivery. “These are the women who were most appropriate for delivery in non-hospital settings and in small hospitals with limited out-of-hours staffing and structural resources,” notes Dr. Mhyre. “Nevertheless, these events can and do occur. As such, all centers should develop institutional protocols and procedures to recognize and address a serious decompensation of maternal medical status.”
A Proactive Approach to Improve Pregnancy Outcomes
According to Dr. Mhyre, non-obstetric clinicians caring for women of childbearing age should note the conditions in the Table and the risk for serious decompensation at the time of delivery. Optimal care depends on a widespread understanding of the interactions between specific medical conditions and the physiology of pregnancy, as well as the diagnostic and pharmacologic strategies that optimize outcomes for both the mother and her fetus. Discontinuing essential medications out of concern for fetal exposure is a common error noted in recent reviews of maternal death.
Professional organizations, such as the American College of Obstetrics and Gynecology, stress the importance of effective contraception to prevent unintended pregnancy. Pre-conceptual counseling and medical optimization are also recommended for women with significant medical conditions who wish to become pregnant. In addition, antepartum care coordination with a multidisciplinary team should be utilized to ensure that pregnancies and significant medical conditions are managed optimally. “Antepartum multidisciplinary coordination and high-quality intrapartum care improves delivery outcomes for women with significant antepartum medical and obstetric disease,” says Dr. Mhyre. “Public health investments to reduce the national burden of delivery-related near-miss morbidity and mortality will have a significant effect if we focus resources on identifying and serving high-risk groups. By identifying characteristics of near misses and thresholds for high-risk patients, the hope is clinicians can optimize care throughout pregnancies.”
Readings & Resources (click to view)
Mhyre J, Bateman B, Leffert L. Influence of patient comorbidities on the risk of near-miss maternal morbidity or mortality. Anesthesiology. 2011;115:963-972. Available at: http://journals.lww.com/anesthesiology/Fulltext/2011/1100/Influence_of_Patient_Comorbidities_on_the_Risk_of.19.aspx.
Hogan M, Foreman K, Naghavi , et al. Maternal mortality for 181 countries, 1980-2008: a systematic analysis of progress towards Millennium Development Goal 5. Lancet. 2010; 375:1609-1623.
Berg C, Callaghan W, Syverson C, Henderson Z. Pregnancy-related mortality in the United States, 1998 to 2005. Obstet Gynecol. 2010; 116:1302-1309.
Clark S, Belfort M, Dildy G, et al. Maternal death in the 21st century: causes, prevention, and relationship to cesarean delivery. Am J Obstet Gynecol. 2008;199:e1-e5.
Clark S, Meyers J, Frye D, Perlin J. Patient safety in obstetrics–the Hospital Corporation of America experience. Am J Obstet Gynecol. 2011; 204:283-287.
Clark S, Hankins G. Preventing maternal death: 10 clinical diamonds. Obstet Gynecol. 2012; 119:360-364.
Kuklina E, Callaghan W. Chronic heart disease and severe obstetric morbidity among hospitalisations for pregnancy in the USA: 1995-2006. BJOG. 2011; 118:345-352.
Kuklina EV, Callaghan WM. Cardiomyopathy and other myocardial disorders among hospitalizations for pregnancy in the United States: 2004-2006. Obstet Gynecol. 2010; 115:93-100.
Karamlou T, Diggs BS, McCrindle BW, Welke KF. A growing problem: maternal death and peripartum complications are higher in women with grown-up congenital heart disease. Ann Thorac Surg. 2011; 92:2193-2198.
Cantwell R, Clutton-Brock T, Cooper G, et al. Saving Mothers’ Lives: Reviewing maternal deaths to make motherhood safer: 2006-2008. The Eighth Report of the Confidential Enquiries into Maternal Deaths in the United Kingdom. BJOG. 2011; 118 (Suppl 1):1-203.
Nelson-Piercy C, Mackillop L, Williams D, et al. Maternal mortality in the UK and the need for obstetric physicians. BMJ. 2011; 343:d4993.