Beyond Your Due Date

An average pregnancy lasts approximately 280 days from the first day of the last menstrual period, and most women give birth somewhere between 38 and 42 weeks of pregnancy.  Based on this, and other factors such as an ultrasound test and the size of your uterus, your physician/midwife determines an estimated due date for your baby’s birth.In reality, only about 5% of children are actually born on their due date.  Most often, women give birth up to three weeks before or two weeks after that date.  However, the date you are given is used as a guide to check your baby’s progress.Health Risks of a Postterm PregnancyOften the reason for a pregnancy going longer than expected is that the exact time of conception is not known.  Also, many women who are having their first babies give birth later than expected.

Problems occur in only a very small percentage of postterm pregnancies.  However, if your pregnancy goes beyond 42 weeks, a baby has an increased risk of certain problems, including:

• Large body size or macrosomia — Complications related to larger body size, which is defined as weighing more than about 10 pounds, can include prolonged labor, difficulty passing through the vagina, and  fractured bones or nerve injury related to difficulty in delivering the shoulders.
• Fetal dysmaturity — Refers to a fetus whose growth in the uterus has been restricted, usually due to a problem with delivery of blood to the fetus through the placenta. This puts the fetus at increased risk for umbilical cord compression, problems after birth such as breathing problems, and long-term neurological problems.
• Meconium aspiration — A postterm fetus is more likely to have a bowel movement, called meconium, into the amniotic fluid.  There is a chance that he or she will inhale some of this fluid; this can cause breathing problems or infection when the baby is born.
• Risks to the mother — Risks to the mother are related to the larger size of postterm infants, and include difficulties during labor, an increase in injury to the vagina, labia, and rectum, and an increased rate of cesarean birth with its associated risks.