The long-term objectives are (1) to evaluate the safety of diagnostic ultrasound and pulsed Doppler in an in vivo system similar to the human, and (2) to observe if changes in animals exposed prenatally to ultrasound (scan mode) are the same for pulsed Doppler. Although considered noninvasive, the safety of prenatal ultrasound exposure still remains uncertain. The current trend to recommend its use as a screening device in all pregnancies further intensifies the importance of these investigations. The proposed studies incorporate a nonhuman primate (Macaca fascicularis) as a model for the human and a commercial ultrasound unit (ATL, MK 600). Periodic measurements of acoustic output including total power, ISPTA, ISPPA, and peak rarefactional and compressional pressure will be included in order to adequately evaluate exposure. In addition, temporal waveforms at each location will be recorded and stored throughout the field. Studies designed to evaluate the teratogenic potential of prenatal exposure in laboratory rodents have indicated an increase in the rate of malformations although long insonation times were incorporated. A significant rise in intrauterine temperature (i.e. >2.5degreesC) may be expected with lengthy exposure although an increase of this magnitude would not be expected in a clinical setting. It is proposed that a moderate increase in intrauterine temperature (<1.0degreesC) can occur with commercial diagnostic equipment which may be capable of impacting on the developing embryo/fetus. This temperature rise may result in a greater absorption of heat within the brain or at the level of the developing bone. Since the intensity values for pulsed Doppler are considerably greater than those employed for routine imaging, the potential impact on the developing conceptus may also be greater. The rise in intrauterine temperature after 10, 20, or 30 minutes of exposure to real-time ultrasound (scan mode) or 5, 10, 15 minutes of pulsed Doppler will be assessed by placing a thermocouple probe transabdominally in vivo with measurements taken intracranially or at the muscle/bone interface (humerus). In addition, the decrease in white blood cells (neutrophils, monocytes) observed in preliminary studies will be pursued. Animals will be exposed to ultrasound (scan mode) prenatally as in prior studies (from 1-5 times weekly during gestation for a total of ~40 exposures). Pre- and postnatal blood samples will be collected for CBC and a differential, and postnatal bone marrow stem cell assay. Finally, the potential effects of pulsed Doppler exposure on the fetus will be evaluated by monitoring neonatal, infant, and juvenile development and performance. These experiments will include the analysis of pre- and postnatal white cell counts and erythrocyte fragility; and postnatal evaluations of simian Apgar scores, birth morphometries, growth, hematologic parameters, bone marrow, and neurobehavioral and behavioral testing.