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.”