Patients undergoing diagnostic or therapeutic procedures during pregnancy, such as:  

• Comprehensive ultrasound  
• Chorionic villus sampling  
• Genetic amniocentesis, fetal surgery or treatment  

Women with medical or surgical disorders, such as:  

• Heart disease  
• High blood pressure  
• Preeclampsia (toxemia)  
• Diabetes or other endocrine disorders  
• Kidney or gastrointestinal disease  
• Infectious diseases  

Healthy women whose pregnancy is at markedly increased risk for adverse outcome, such as:  

• Abnormal AFP (alpha fetoprotein) blood test  
• Twins, triplets or more  
• Recurrent pre-term labor and delivery
• Premature rupture of membranes 
• Recurrent pregnancy loss
• Suspected fetal growth restriction