postterm

Postterm is a medical term used chiefly in obstetrics to describe a pregnancy that continues beyond the expected duration of gestation. In most obstetric practice, postterm refers to 42 completed weeks of gestation or longer (≥294 days). Some sources differentiate late-term as 41 weeks to 41 weeks 6 days and postterm as 42 weeks or more; definitions vary by guideline.

Causes and risk factors: In most cases the cause of prolonged gestation is unknown. Risk factors include nulliparity, advanced maternal age, prior postterm pregnancy, obesity, and a family history. Placental aging and reduced placental reserve are thought to contribute to risk in late gestation.

Monitoring and management: After 41 weeks, fetal assessment becomes routine. Surveillance may include nonstress testing, biophysical profiling, and ultrasound to assess amniotic fluid and fetal growth. If tests indicate fetal well-being, management may be expectant with close monitoring; many guidelines recommend induction of labor at around 41 weeks or 41+0 to 41+6 weeks to decrease risks. Cervical ripening and induction methods are used if labor does not begin spontaneously.

Risks and outcomes: Postterm pregnancy is associated with higher rates of cesarean delivery, prolonged labor, and postpartum hemorrhage for the mother, and oligohydramnios, placental insufficiency, meconium-stained fluid, fetal distress, and stillbirth for the baby. With timely monitoring and decision-making, outcomes can be favorable.

Terminology usage: The term is primarily used in obstetrics and perinatal medicine; outside this field, usage is rare.