The well-being of the fetus is strongly influenced by the status of the critically ill mother. Understanding basic principles of placental gas exchange is important when caring a pregnant patient in the intensive care unit (ICU). Aside from the few cases in which delivery is the preferred therapy, managing a pregnant patient in ICU should focus primarily on maternal well-being and only secondarily on the effects of interventions on the fetus. If preterm delivery is anticipated, administration of antenatal corticosteroids to the mother will decrease rates of common complications of prematurity of the newborn. The usual rule is to optimize the maternal medical condition and allow the fetus and placenta to take care of themselves. Certain fetal conditions such as severe intrauterine growth restriction may also provide a reason to separate the fetus from the mother.

This chapter discusses congenital diaphragmatic hernia (CDH) from a perspective of antenatal management, including fetal intervention. It summarizes actual survival rates when this condition is managed after birth, essentially showing that there is no effective postnatal therapy in a subset of fetuses. Prediction methods are typically based on estimation of lung size by ultrasound and determination of liver herniation into the thorax. Three-dimensional (3D) ultrasound (US) and MRI both allow measurement of absolute lung volumetry. MRI allows better visualization of the ipsilateral lung than 3D US. Preliminary work on the use of diffusion-weighted imaging (DWI)-MRI as a tool to differentiate between normal and pathological lung development has shown a significant relationship between DWI-MRI parameters and gestational age in the normal fetus. The chapter also describes the current clinical experience with fetal surgery, including the design of trials that will have to determine the place of fetal surgery.