Postterm pregnancy is when a woman has not yet delivered her baby after 42 weeks of gestation, two weeks beyond the typical 40-week duration of pregnancy. Postmature births carry risks for both the mother and the baby, including fetal malnutrition, meconium aspiration syndrome, and stillbirths. After the 42nd week of gestation, the placenta, which supplies the baby with nutrients and oxygen from the mother, starts aging and will eventually fail. Postterm pregnancy is a reason to induce labor. Definitions
The management of labor and delivery may vary depending on the gestational age. It is common to encounter the following terms when describing different time periods of pregnancy. Postterm – ≥ 42 weeks + 0 days of gestation (> 293 days from the first day of last menstrual period, or > 13 days from the estimated due date)
Late term – 41 weeks + 0 days to 41 weeks + 6 days of gestation
Full term – 39 weeks + 0 days to 40 weeks + 6 days of gestation
Early term – 37 weeks + 0 days to 38 weeks + 6 days of gestation
Preterm – ≤ 36 weeks + 6 days of gestationBesides postterm pregnancy, other terminologies have been used to describe the same condition (≥ 42w+0d), such as prolonged pregnancy, postdates, and postdatism. However, these terminologies are less commonly used to avoid confusion.Postterm pregnancy should not be confused with postmaturity, postmaturity syndrome, or dysmaturity. These terms describe the neonatal condition that may be caused by postterm pregnancy instead of the duration of pregnancy.
Usually, a red color indicates a flow toward the ultrasound transducer, while blue indicates a flow away from the transducer. Based on the display, doctors can evaluate blood flow to the umbilical arteries, umbilical veins, or other organs such as heart and brain. Nonstress test
Nonstress test (NST) is a type of electronic fetal monitoring that uses a cardiotocograph to monitor fetal heartbeat, fetal movement and mothers contraction. NST is typically monitored for at least 20 minutes. Signs of a reactive (normal) NST include a baseline fetal heart rate (FHR) between 110 and 160 beats per minute (bpm) and 2 accelerations of FHR of at least 15 bpm above baseline for over 15 seconds. Vibroacoustic stimulation and longer monitoring may be needed if NST is non-reactive. Biophysical profile
A biophysical profile is a noninvasive procedure that uses the ultrasound to evaluate the fetal health based on NST and four ultrasound parameters: fetal movement, fetal breathing, fetal muscle tone, and the amount of amniotic fluid surrounding the fetus. A score of 2 points is given for each category that meets the criteria or 0 points if the criteria are not met (no 1 point). Sometimes, the NST is omitted, making the highest score 8/8 instead of 10/10. Generally, a score of 8/10 or 10/10 is considered a normal test result, unless 0 points is given for amniotic fluid. A score of 6/10 with normal amniotic fluid is considered equivocal, and a repeated test within 24 hours may be needed.