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The connection between maternal smoking during pregnancy and a lower birth weight in the baby is confirmed. The maternal blood thiocyanate level, as measured post partum, was found to be higher in smokers than in non‐smokers. A significant negative correlation was found between the maternal thiocyanate level and the birth weight. A significant association was found between the thiocyanate levels in maternal and umbilical cord blood. A similar correlation was found between the umbilical cord blood and the amniotic fluid thiocyanate concentrations.

The fetal heart rate response to a controlled sound stimulus was recorded in 36 pregnant women before and after a maternal peroral dose of either 80 mg propranolol, or placebo. The sound stimulation was repeated 60 minutes, 120 minutes and 180 minutes after the drug administration. The fetal heart rate response to sound was significantly depressed by this moderate dose of propranolol. The sound stimulation method is found to reflect sensitively the immediate influence of propranolol on the fetus.

Fetal Heart Rate (FHR) Responses to Controlled Sound Stimuli were Compared in the 32nd, 35th and 39th week of pregnancy. Though a tendency to a greater FHR response to sound was found as gestation advanced, this increase would seem to be so small that it may be ignored in practice. The earlier demonstrated influence of stimulus intensity and prestimulus heart rate level on the FHR response to sound were confirmed.

A method for electronic supervision of the human fetus based upon controlled sound stimulation of the fetus and the fetal heart rate response was used to evaluate the effect of pethidine on the fetus. Half an hour after intramuscular injection of 100 mg pethidine in the mother, the fetal heart rate response to sound stimulation was already depressed in 10 out of 20 cases. A general depression of the heart rate response to sound was found 2 and 3 hours after the injection. The fetal heart rate response to sound stimulation seems to constitute a sensitive record of pethidine's influence.

Ninety-tour women with high-risk pregnancies were referred to the Aker University Hospital, Department of Obstetrics, and monitored by Doppler velocimetry and conventional cardiotocography. The peak systolic/end diastolic (A/B) ratio was measured in the velocity waveform obtained in the umbilical artery blood flow. The non-stress test (NST) was classified according to the Fischer scores. In this mixed group of high-risk pregnancies, the sensitivity of the A/B ratio to predict fetal growth retardation was 71%, predictive value 57% and specificity 77%. The corresponding values for NST were 39%, 65% and 90%. It is concluded that Doppler velocimetry is more sensitive than cardiotocography for identifying fetal growth retardation. In an attempt to further improve the detection rate of fetal pathology, the cases with abnormal NST scores were added to those with high A/B ratios and collectively defined as abnormal. In consequence, only an insignificant improvement in sensitivity (79%) could be achieved. When the A/B ratio is normal, there seems little justification for expending time, effort and resources in routine use of cardiotocography.

The fetal heart rate (FHR) response to a controlled sound stimulus of 80 dB was registered in 152 at-risk pregnancies. Thirty-four of the infants showed signs of an intra-uterine pathological condition at birth, whereas 118 infants were clinically unaffected. The mean heart rate response was significantly weaker in the pathological group than in the normal group. A FHR response of less than 15 bpm was found to give a test sensitivity of 53%. The differences between the two groups revealed by the sound stimulation test corresponded to differences in birth weights and in Apgar score after 1 minute. The results indicate that the sound stimulation test is sensitive to minor changes in the condition of the fetus.