A primigravida with abnormal sonographic findings found to have decreased alpha fetoprotein (AFP) levels. The fetus may have:

AFP is synthesized early in gestation by the fetal yolk sac and later by the fetal gastrointestinal tract and liver. The normal concentration gradient between fetal plasma and maternal serum is on the order of 50,000:1. Low Levels of AFP seen in: Obesity Diabetes Chromosomal trisomies Gestational trophoblastic disease Fetal death Overestimated gestational age Selected conditions with high levels of AFP: Underestimated gestational age Multifetal gestation Neural-tube defects Gastroschisis Omphalocele Low maternal weight Liver necrosis Renal anomalies--polycystic kidneys, renal agenesis Osteogenesis imperfecta Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. (2010). Chapter 13. Prenatal Diagnosis and Fetal Therapy. In F.G. Cunningham, K.J. Leveno, S.L. Bloom, J.C. Hauth, D.J. Rouse, C.Y. Spong (Eds), Williams Obstetrics, 23e.