October 22, 1996
FOR RELEASE: Immediate
Computer software predicts gestation length and risk of preterm birth
More than a century and a half after the standard method of predicting a woman's due date was established, a new theory provides more accurate prediction and also identifies those at high risk for preterm delivery.
The Mittendorf-Williams Rule was developed using a new theory to predict length of gestation and the risk for preterm birth in singleton pregnancies. The computer model uses sixteen significant factors such as maternal age, pre-pregnancy weight, race, college education, alcohol and coffee use, hypertension, and other medical conditions to compute a womans due date and determine if she is at high risk for giving birth sooner than 37 weeks gestation.
Mittendorf-Williams Rule is named for co-creators Robert Mittendorf, M.D., Dr.P.H., assistant professor and director of health studies in the department of obstetrics and gynecology at the University of Chicago Medical Center, and Michelle A. Williams, Sc.D., epidemiologist at the University of Washington.
The current due-date predictor--Naegele's rule--was devised in 1838 by Franz Carl Naegele and has been used by obstetricians around the world for more than 150 years. Naegele's rule is based on the belief that human gestation is ten menstrual cycles (nine months plus seven days), not on empirical data.
A retrospective study by Mittendorf and colleagues (Obstetrics and Gynecology, 1990;75:929-32) determined that white women with singleton pregnancies receiving private care averaged seven days longer gestation than Naegele's rule predicts. A second study by Mittendorf (American Journal of Obstetrics and Gynecology, 1993;168:480-4) concluded that there are several factors including number of previous births, age and race that can be used to determine the length of pregnancy more accurately than Naegele's rule, which does not take other factors into consideration.
Few women deliver exactly on their due date. A prospective study comparing the Mittendorf-Williams Rule found it to be twice as accurate as Naegele's rule in predicting gestation.
More importantly, the software can predict the likelihood of preterm delivery, which affects 400,000 births annually in the United States.
"Until now there has been no successful way to statistically identify women at high risk for preterm delivery," said Mittendorf. "By identifying these women we may be able to lower the infant mortality rate by intensifying a woman's prenatal care, and medically manage patients differently based on this new information."