UT Southwestern Study Defines Anemia in Pregnancy Using Uncomplicated U.S. Cases
Maternal anemia has the same definition across the sociodemographic spectrum, according to a UT Southwestern study of a diverse population of uncomplicated patients. The findings, published in PLOS ONE, will help guide both prevention and treatment of maternal anemia, a common cause of complications.
The researchers studied records for a combined 2,000 pregnant patients at William P. Clements Jr. University Hospital and Parkland Memorial Hospital, both located in Dallas, and found the definition of anemia is the same in both hospital populations.
“To date, definitions for anemia were derived from four small European studies in pregnant women in the late 1970s to 1980s,” said Catherine Spong, M.D., Chair and Professor in the Department of Obstetrics and Gynecology. “There have been no studies to determine if they are valid in a modern United States pregnant population. A definition based on modern U.S. populations has been sorely needed and is critical given the impact of blood loss on maternal mortality.”
Catherine Spong, M.D.
Blood transfusion is a common cause of severe maternal morbidity, Dr. Spong said. According to the Centers for Disease Control and Prevention, maternal mortality complicated 20.1 per 100,000 live births in 2019 in the U.S., a higher rate than other medically developed countries. To define cutoff values for anemia, it is critical to use a normal, healthy, and uncomplicated obstetric population. Anemia is defined by the American College of Obstetricians and Gynecologists as a hematocrit (red blood cell count) less than the 5th percentile.
“This contemporaneous study has identified ways to define those at highest risk of maternal mortality,” said Dr. Spong. “This will assist labor and delivery clinicians in determining high-risk patients, allowing them to prepare by alerting the blood bank, or having postpartum hemorrhage treatments readily available at delivery.”
In addition, this will translate into the timing of interventions, such as iron fortification and other measures to increase the proportion of red blood cells in the mother’s blood prior to delivery, Dr. Spong said.
Each group of 1,000 patient records included 250 patients from 2011, 2013, 2015, and 2018. The hematocrits were obtained in each trimester of pregnancy. In the public and private populations, 777 and 785 women presented in the first trimester, while 223 and 215 presented in the second. The women at the private hospital were more likely to be older, Caucasian race, first-time moms, and to seek health care earlier in pregnancy. The hematocrits were compared between the women in the two hospitals, one predominantly private and one public, and were clinically indistinguishable.
Dr. Spong also serves as Chief of the Department’s Division of Maternal-Fetal Medicine.
Additional UT Southwestern researchers involved include Amanda C. Zofkie, W. Holt Garner, Rachel C. Schell, Alexandra S. Ragsdale, Donald D. McIntire, and Scott W. Roberts.
Dr. Spong holds the Paul C. MacDonald Distinguished Chair in Obstetrics and Gynecology.