A postterm newborn is a baby delivered at or after 42 weeks of gestation.
Near the end of a term pregnancy, the function of the placenta decreases, providing fewer nutrients and less oxygen to the fetus.
Low blood sugar (glucose) is a particular problem in postterm newborns.
Postterm newborns have dry, peeling, loose skin and may appear abnormally thin because they have not received sufficient nutrition at the end of the pregnancy.
The diagnosis is based on the appearance of the newborn and the estimated gestational age.
Typically treatment is focused on providing good nutrition and general care.
Some postterm newborns are not breathing at birth and need to be revived (resuscitated).
Gestational age refers to the number of weeks of pregnancy. The gestational age is determined by counting the number of weeks between the first day of the mother''s last menstrual period and the day of delivery. This time frame is often adjusted according to other information doctors receive, including the results of early ultrasound scans, which give additional information regarding the gestational age. The baby is estimated to be due (the due date) at 40 weeks of gestation.
Newborns are classified by gestational age as
Preterm: Delivered before 37 weeks of gestation
Full term: Delivered at 37 to before 42 weeks of gestation
Postterm: Delivered at 42 weeks or more of gestation
Postterm delivery is much less common than preterm (premature) delivery. Why a pregnancy continues beyond term is usually unknown. Pregnant people who have had one postterm delivery are at increased risk of having another one.
Near the end of a term pregnancy, the level of amniotic fluid decreases and the placenta (the organ that provides nourishment to the fetus) becomes smaller and less effective in providing oxygen and nutrients. To compensate, the fetus begins to use its own fat and carbohydrates (sugars) to provide energy. As a result, its growth rate slows, and its weight may even decrease.
Complications during and after delivery
If the placenta shrinks enough, it may not provide adequate oxygen to the fetus, particularly during labor (see Birth Asphyxia). A lack of adequate oxygen may result in fetal distress (signs that the fetus is not well) and, in extreme cases, may result in injury to the brain and other organs.
Fetal distress can cause the fetus to pass meconium (the fetus'' stools) into the amniotic fluid. The fetus may reflexively take deep, gasping breaths triggered by the distress and thereby inhale the meconium-containing amniotic fluid into the lungs before birth. As a result, the newborn may have difficulty breathing after delivery (meconium aspiration syndrome).
If the pregnancy continues significantly beyond term, the fetus may die.
After delivery, postterm newborns are prone to developing low blood sugar (glucose) levels (hypoglycemia) because they have exhausted their supply of stored fat and carbohydrates or because they have a high level of insulin. If the fetus has been exposed to high glucose levels because the mother''s diabetes was poorly controlled during pregnancy, the fetus usually has a high level of insulin. At the time of delivery, the placental supply of glucose is abruptly stopped, and the high level of insulin can rapidly the baby''s blood sugar level, resulting in hypoglycemia.
