Health + Safety
Why Some Babies Are Overdue
The world is eagerly waiting to hear news of the birth of the royal baby. A royal source told CNN that the due date was Saturday, July 13, which would mean that the Duchess of Cambridge is several days overdue.
Why is it taking the future prince or princess of Cambridge so long to arrive?
First-born babies are less likely to arrive on time — they’re either too early or too late, studies have found. A normal pregnancy lasts about 40 weeks, according to the
American College of Obstetricians and Gynecologists. After 42 weeks, the pregnancy is considered to be post term. However, doctors usually induce labor before the pregnancy reaches this stage.
Doctors predict the due date by noting the first day of the mother’s last period, as well as measuring the size of her uterus early on in the pregnancy. However, differences in menstrual cycles and inaccuracies in remembering the actual date of the mother’s last period make predicting a due date more of an art than a science.
“Often, there is a miscalculation of the due date in the first place,” Dr. Neil Sloane, clinical director for obstetrics and gynecology at Delaware Valley Health in Philadelphia, noted. “And when we examine a supposedly overdue baby, they don’t look like they’re overdue.”
Mothers may also be more likely to deliver late if overdue pregnancies run in the family. “Family history of overdue pregnancies is a stronger predictor than whether or not it is a first-time mother,” said Dr. Daniela Carusi, director of general gynecology and surgical obstetrics at Brigham and Women’s Hospital in Boston.