Hematologic and growth-related effects of frequent prenatal ultrasound exposure in the long-tailed macaque (Macaca fascicularis).

Prior investigations have shown that reduced birth weights and transient neutropenias result from frequent exposure of monkey fetuses to ultrasound. To further explore these findings, 26 animals were studied (16 exposed, 10 controls; "triple mode"; ATL Ultramark 9 with HDI; ISPTAd approximately 645 to 714 mW/cm2). Exposures were performed daily for 5 days each week from gestational days (GD) 21 to 35 (5 min), three times weekly from GD 36 to 60 (5 min), then weekly from GD 61 to 153 +/- 1 (10 min). Fetal blood samples (FBS) were collected for complete blood counts (CBCs), hematopoietic progenitor assay, circulating insulin-like growth factors (IGF-I, IGF-II) and binding proteins (IGFBP-3) (GD 120, 140, 153 +/- 1). Animals were delivered by Cesarean section at term (GD 153 +/- 1), and body weights, morphometrics, CBCs, and bone marrow aspirates assessed at delivery and postnatally for 3 months. Fetal neutropenias were noted in exposed animals in addition to reduced circulating progenitors (colony forming unit-granulocyte-macrophage [CFU-GM]). Growth of CFU-GM from bone marrow was exuberant at term, whereas circulating levels were diminished comparable to prenatal samples. Exposed animals were smaller at birth; marked reductions in IGFBP-3 were noted prenatally. These data suggest that frequent prenatal ultrasound exposure can transiently alter the neutrophil lineage, although these findings may be the result of enhanced margination and organ sequestration. Data also suggest that transient, altered growth patterns may be due to perturbations of the IGF axis.