By the early 1900s, clinical evidence acknowledged an association between both prematurity and perinatal asphyxia and cerebral palsy. Sampling is not continuous. Insufficient audibility of fetal heart tones due to the contracting uterus and abdominal muscles. Developed commercially in the late 1960s. This occurs because the placenta fails to deliver sufficient oxygen to the fetus and to remove carbon dioxide from the fetus.
Uterine contractions associated with labor cause a decrease in uterine blood flow.
The decrease in uterine blood flow is of no consequence to the normal fetus during normal pregnancy because of placental reserve. Certain obstetrical complications cause a decrease in placental functions which causes a decrease in placental blood flow with uterine contraction resulting in a progressive decrease in oxygenation to the fetus. Detection of high risk pregnancy. Estimation of fundal height and fetal weight. Auscultation of fetal heart rate.