Similarities in developmental biology between human and nonhuman primates have resulted in the use of macaque species as models in perinatal research. Studies have frequently included invasive surgical procedures or may have required "blind" injections. Several techniques have been established in human subjects using ultrasound as a guide such as cordocentesis and fetal therapy. These techniques have been applied to the nonhuman primate laboratory setting, which significantly decreases the risk of pregnancy loss due to experimental intervention.