Maternal obesity and macrosomia

Obesity is becoming a worldwide epidemic. Maternal obesity and fetal macrosomia carry an increase in risk of neonatal and maternal complications and even increased perinatal mortality. However, the definition of fetal macrosomia remains controversial. The use of any fixed threshold for macrosomia hinders our ability to discriminate between fetuses who are abnormally grown and those with normal body composition which are constitutionally large. Efforts should be directed to diagnose and treat the accelerated (pathologically) overgrown fetus. This chapter will look into the underlying mechanisms resulting in fetal macrosomia, the consequences of macrosomia (both long and short term), and the specific methods of fetal weight estimation in obese women. We hope to improve our understanding of this abnormality so that appropriate management programs could be devised, and the outcome of mother and fetus improved.