attributed to irregular menstrual cycles. When the menstrual period is irregular it is difficult to judge the moment of ovulation and subsequent fertilization and pregnancy. Some postmature pregnancies may not be postmature in reality due to the uncertainty of mother's last menstrual period. However, in most countries where gestation is measured by ultrasound scan technology, this is less likely. Monitoring Once a pregnancy is diagnosed postterm, usually at or greater than 42 weeks of gestational age, the mother should be offered additional monitoring as this can provide valuable clues that the fetal health is being maintained. Fetal movement recording Regular movements of the fetus is the best sign indicating that it is still in good health. The mother should keep a "kick-chart" to record the movements of her fetus. If there is a reduction in the number of movements it could indicate placental deterioration. Doppler fetal monitor Doppler fetal monitor is a hand-held device that is routinely used in prenatal care. When it is used correctly, it can quickly measure the fetal heart rate. The baseline of fetal heart rate is typically between 110 and 160 beats per minute. Doppler flow study Doppler flow study is a type of ultrasound that measures the amount of blood flowing in and out of the placenta. The ultrasound machine can also detect the direction of blood flow and display it in red or blue. 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 mother's 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