Below is by no means an exhaustive list of terms, but does include many of the terms used on this website.

• Alpha fetoprotein – a protein produced by the fetal liver
  
• Aplasia - absence of
  
• Aqueductal stenosis - passageway (aqueduct) connecting cavities of the brain becomes narrow
  
• Ascites - fluid accumulation
  
• Atresia (or atretic) - missing or blocked
  
• Atrial septal defect - defect in the division of the two atria (upper portion) of the heart
  
• Beckwith-Wiedemann - a genetic condition characterized by overgrowth
  
• Biparietal diameter - largest side-to-side diameter of head
  
• Cerebellar vermis - a narrow structure between the hemispheres of the cerebellum (back of the brain)
  
• Color flow Doppler - allows visualization of blood flow
  
• Cystic hygroma - sac-like structure filled with lymph
  
• Deciduas - lining of the uterus during pregnancy
  
• Dominant - one copy of the gene responsible needs to be mutated for the condition to arise
  
• Echogenic foci - bright spot seen on ultrasound usually due to increased calcification

• Ectopic - outside the uterus
  
• Edema - excessive accumulation of fluid
  
• Endocardial cushions - primitive tissue which divides the heart into chambers
  
• Free Beta-hCG - protein produced by the baby's placenta
  
• Hepatosplenomegaly - enlarged liver and spleen
  
• Hypoplasia - under-development of
  
• Hypoplastic - under-development
  
• Macrocephaly - large lead size

• Microcephaly - small head size
  
• Monosomy X - females with 1 X chromosome instead of 2
  
• Myometrium - muscular outer layer of the uterus
  
• Neuroepithelial folds - tissue made up of sensory cells that serve in the reception of external stimuli
  
• NICU - newborn intensive care unit
  
• Nuchal translucency - space at the back of the fetal neck between the skin and muscle layer where fluid accumulates
  
• Occipital - lower back portion of the skull
  
• Occipitofrontal - front to back diameter of head
  
• Olfactory bulbs - responsible for smell
  
• Oligohydramnios - decreased amount of amniotic fluid
  
• Open neural defect - failure of the fetal spine to close properly
  
• PAPP-A - protein produced by the ovaries
  
• Paracranial - outside the cranium
  
• Phenylketonuria - genetic condition which affected individuals cannot break down a chemical called phenylalanine
  
• Polyhydramnios - extra amount of amniotic fluid
  
• Posterior fossa - cavity in the back part of the skull which contains the cerebellum and brain stem
  
• Pulmonary artery - the blood vessel that takes blood from the heart to the lungs
  
• Recessive - both copies of the gene responsible needs to be mutated for the condition to arise
  
• Subarachnoid space - space through which the spinal fluid circulates
  
• Subcutaneous - under the skin
  
• Teratogen - exposure which could lead to birth defects
  
• Thalamus - area of the brain that helps process information from the senses and transmit it to other parts of the brain
  
• Triple screen - blood test examing 3 biochemicals in the mother's blood and is performed during the 2nd trimester as a screening tool to provide a risk assessment for Down syndrome, trisomy 13 and trisomy 18 (two more severe chromosome problems)
  
• Triploidy - 3 instead of 2 copies of all chromosomes
  
• Umbilicus - bellybutton
  
• Ventricles - cavities in the brain filled with cerebral spinal fluid
  
• Ventricular septal defect - defect in the division of the two ventricles (lower portion) of the heart
  
• X-linked - the gene responsible for the condition is located on the X chromosome