The normal length of pregnancy is 37 to 41 weeks. Early term is from 37 weeks to 38 weeks and 6 days. Full term is 39 weeks to 40 weeks and 6 days. Late term is 41 weeks to 41 weeks and 6 days. Postmaturity (dysmaturity) is a word used to describe babies born after 42 weeks. Very few babies are born at 42 weeks or later. Other terms often used to describe these late births include post-term, postmaturity, prolonged pregnancy, and post-dates pregnancy.
Researchers don't know why some pregnancies last longer than others. Sometimes a mother's pregnancy due date is off because she is not sure of her last menstrual period. Getting the date wrong may mean the baby is born earlier or later than expected. Getting an ultrasound in the first trimester (the first 12 weeks) is the most accurate way to tell the date of pregnancy, unless the date of conception is specifically known, such as with in vitro fertilization.
Postmaturity is more likely to happen when a mother has had a post-term pregnancy before. After one post-term pregnancy, the risk of a second post-term birth increases by 2 to 3 times. Other, minor risk factors include:
Each baby may show different symptoms of postmaturity. Some of those symptoms are:
Symptoms of postmaturity sometimes look like other health conditions. Make sure your child sees his or her healthcare provider for a diagnosis.
Your baby's healthcare provider will check:
Your healthcare provider will check your unborn baby's health and look for any problems. Tests may need to be done such as:
Your healthcare provider may decide to start your labor early, depending on several things. During labor, your baby's heart rate may be watched with an electronic monitor. This will help spot changes in the heart rate caused by low oxygen levels. Changes in your baby's condition may require a cesarean delivery.
Special care of the post-term baby may include:
Post-term babies are born after the normal length of pregnancy. Because of this they may grow larger than full-term babies. This may be a problem during labor and delivery.
Also, because the placenta ages toward the end of pregnancy, it may not work as well as before. Concerns from placental aging include:
Knowing your due date is the best way to know if your baby may be post-term. Keep track of the first day of your menstrual period. This can help estimate a baby's due date. An ultrasound test early in pregnancy can also help your healthcare provider figure out your baby’s age by checking the baby’s size. Ultrasound is also a good way to check the placenta for signs of aging.
Tips to help you get the most from a visit to your child’s healthcare provider:
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