Amniotic Fluid Tandem Mass Spectrometry for Pregnancies Complicated by NIH and Severe Symmetrical IUGR

NIH Inclusion Criteria: * Singleton gestation * 18 years of age or older * Excess extracellular fluid in at least two fetal sites as noted by ultrasound: abdomen (ascites), the chest (pleural and pericardial effusions), the skin (edema \> 5mm), the amniotic cavity (polyhydramnios), and the placenta (thickening \> 6cm) * NIH diagnosis \> 15w0d gestation * Diagnostic amniocentesis performed at \> 15w0d gestation NIH Exclusion Criteria: * Immune-mediated hydrops fetalis as diagnosed by maternal red cell antigens and fetal anemia suspected by middle cerebral artery doppler ultrasound and/or confirmed by percutaneous umbilical blood sampling * Structural anomaly identified by ultrasound * Chromosomal aneuploidy * Multiple gestations IUGR Inclusion Criteria: * Singleton gestation * 18 years of age or older * Severe symmetrical IUGR defined as a \> 3 week lag of all fetal ultrasound measurements (biparietal diameter, head circumference, abdominal circumference, and femur length) * IUGR diagnosis between 24-32 weeks gestation * Diagnostic amniocentesis performed prior to 32 weeks gestation IUGR Exclusion Criteria: * Asymmetrical IUGR * Structural anomaly identified by ultrasound * Chromosomal aneuploidy * Multiple gestations