Sasi K. Pillay

Identifying the pregnancy at risk for intrauterine growth retardation: Possible usefulness of the intravenous glucose tolerance test☆

Antenatal detection of intrauterine growth retardation (IUGR) remains problematic. Previous animal and human studies have documented a relationship between increased substrate delivery to the fetus, e.g., in diabetes mellitus, and the birth of large-for-gestational age infants. The purpose of the study of 55 pregnancies, in which intravenous glucose tolerance tests (IVGTTs) were performed during the third trimester, was to examine the hypothesis that evidence of decreased availability of substrates for fetal growth precedes the birth of small-for-gestational age (SGA) infants; hence, the IVGTT might be useful for the detection of pregnancies complicated by IUGR. Increased glucose utilization rates (kt) and 10-minute plasma glucose concentrations and decreased plasma glucose concentrations at fasting and 60 minutes were found to be significantly associated with decreased infant birth weight, adjusted for gestational age. The Kt and 10- and 60-minute glucose values together could account for 40% of the variance in age-adjusted birth weight (r = 0.63, p less than 0.01). The IVGTTs in the pregnancies resulting in the birth of SGA infants were characterized by kt greater than 2 and plasma glucose levels at fasting of less than 64 mg/dl, at 10 minutes of greater than 193 mg/dl, and at 60 minutes of less than 82 mg/dl. When the kt was greater than 2, six (30%) of 20 infants were SGA; when the kt was less than or equal to 2, none (0%) of the 35 infants was SGA. These results suggest that, regardless of the underlying reason for the association, parameters of maternal glucose metabolism may be useful in detecting the pregnancy at risk for IUGR.

A comparison between maternal, tocodynamometric, and real-time ultrasonographic assessments of fetal movement

Fetal movements were simultaneously studied with maternal perception, tocodynamometry, and real-time ultrasonography. A comparison between these three modalities demonstrated good agreement. The percentage of agreement improved with increasing duration of fetal movements. For fetal movements lasting longer than 3 seconds, the agreement between ultrasonography and tocodynamometry was 95.6%. These findings suggest that tocodynamometry is a sensitive method for studying fetal movements.

Antenatal investigation of human fetal systolic time intervals

A noninvasive method for measuring the antenatal human fetal systolic time intervals with the use of the transabdominal fetal electrocardiogram and Doppler cardiogram is described. Unique interactive computer routines were developed for rapid and accurate determination of the pre-ejection period (PEP), ventricular ejection time (VET), PEP/VET ratio, and fetal heart rate (FHR). Thirty normal patients were monitored between 20 and 40 weeks of gestation. A regression analysis of the fetal systolic time intervals and FHR against gestational age was done. PEP and PEP/VET ratio were significantly correlated to the gestational age, while VET and FHR were not.

A Micropower Pulsewidth-Modulation-Pulse-Position-Modulation Two-Channel Telemetry System for Biomedical Applications

A novel micropower, two-channel telemetry system, which has been used to transmit the occurrence of the QRS complex of the heart waveform and temperature information, is described. The system employs pulsewidth-modulation (PWM) and pulse-position-modulation (PPM) methods plus a few unique circuits and system-design techniques so that it has the following desirable features. 1) The transmitting unit consumes extremely low power due to low duty cycle and yet delivers high peak power for better receiving. In addition, the unit is compensated (not regulated) for battery voltage variation. 2) By means of adaptive threshold, pulse-width-discrimination and pulse-rate-discrimination networks, the receiving unit is relatively noise free in signal identification. Information in analog and digital form are available at the output for convenience. A prototype system was designed and fabricated. Test results are presented. Due to the availability of the integrated circuits on the market, medical doctors and biologists will be able to duplicate the system if the system-size problem is not severe. Although the design was not trivial, the implementation is quite straightforward. Hence it is believed that device or integrated-circuit manufacturers would be able to implement it in a much more compact form.

Correlation between Gestational Age and Fetal Activity Periods

Cyclic patterns of active and quiet fetal activity were evaluated in 36 clinically normal gravidas between 27 and 42 weeks of gestation. All infants were subsequently delivered between 37 and 42 weeks of gestation, were clinically normal and of appropriate weight for gestational age. Active-quiet cycles occurred less frequently and were of longer duration with increasing gestational age. Regression analysis of the number of active-quiet cycles with gestational age yielded a correlation coefficient of 0.52 (p less than 0.01). The similarity of fetal active-quiet cycles and active and quiet sleep cycles observed after birth is noted.