New research by University of Maryland School of Public Health doctoral candidate Ms. Katheryne Downes finds that mothers who have a cesarean delivery before labor onset are at increased risk of placenta previa in subsequent pregnancies. The paper “Prior Prelabor or Intrapartum Cesarean Delivery and Risk of Placenta Previa” was published in the American Journal of Obstetrics & Gynecology and was based on a study she conducted in 2013 while participating in the Summer Internship Program in Biomedical Research at the National Institutes of Health (NIH).
The retrospective study utilized electronic medical records collected from 2002-2010 at 20 Utah hospitals and focused on 26,987 women who had their first two consecutive singleton births during that period. Ms. Downes, who is pursuing her PhD in Maternal and Child Health in the department of family science, and the research team examined the association between cesarean delivery in the first pregnancy and placenta previa in the second pregnancy while distinguishing cesarean delivery prior to onset of labor (prelabor) from intrapartum cesarean delivery (cesarean delivery after labor onset). Placenta previa is a condition in which the placenta either partially or completely covers the internal opening of the cervix. It can cause severe bleeding before or during delivery and typically necessitates a cesarean delivery for the safety of both mother and child.
“We found that first pregnancy prelabor cesarean delivery was associated with more than a two-fold increased risk of placenta previa in the second pregnancy,” Ms. Downes explains. “The results are important because in the U.S., one out of every three births is by cesarean, and in 2006, it became the most common surgical procedure in the U.S.”
Although a cesarean delivery can be a life-saving procedure, it is also associated with significant increases in risk of surgical complications and re-hospitalization for the mother, as well as higher risk of complications requiring admission to the Neonatal Intensive Care Unit (NICU) for the baby. There are also long-term risks in subsequent pregnancies such as uterine rupture and development of placental disorders, such as the one being investigated in this study.
The American College of Obstetricians and Gynecologists (ACOG), in collaboration with the Society for Maternal-Fetal Medicine (SMFM), is actively advocating to reduce primary (first) cesarean deliveries with a focus on reducing the number that are performed for non-medical reasons including maternal requests (either for convenience or because they don’t want to labor) or for “soft indications” which are not considered necessary.
This study revealed that cesarean delivery performed prior to the onset of labor (such as those that are scheduled for maternal request and for some other soft indications) are associated with an increased risk of developing placenta previa in subsequent pregnancies.
Ms. Downes was awarded an Intramural Fellowship to work with a research team led by Dr. Katherine Grantz, a maternal-fetal medicine physician and investigator with the Epidemiology Branch in the Division of Intramural Population Health Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Ms. Downes worked on data from the NICHD Consecutive Pregnancies Study and first presented her research last February at the 2014 Society for Maternal-Fetal Medicine Conference.
Ms. Downes is currently working on her dissertation in collaboration with NICHD, with a volunteer appointment as a predoctoral research fellow in epidemiology. Her dissertation examines labor and neonatal outcomes associated with placental abruption.
CDC report: http://www.cdc.gov/nchs/data/databriefs/db35.htm
ACOG Consensus post: http://www.acog.org/Resources-And-Publications/Obstetric-Care-Consensus-Series/Safe-Prevention-of-the-Primary-Cesarean-Delivery