Labor Induction in Case of Fetal Growth Restriction (FGR)

Abstract

Clinicians consider a range of variables when formulating decisions regarding the diagnosis, monitoring plan, and ultimately the decision to recommend the delivery of a growth-restricted fetus. The differential diagnosis of a pathological fetal growth pattern is initially considered via the history, a physical and laboratory examination of the pregnant person, as well as a comprehensive fetal ultrasound examination. These factors allow a broad distinction between pre-existing disease in the pregnant person, constitutionally small normal growth, placenta-mediated Fetal Growth Restriction (FGR), and intrinsic fetal disease. Most commonly, pathological growth restriction is mediated by underlying placental diseases, of which maternal vascular malperfusion is the most common, and often results in co-existent hypertension. A program of combined monitoring of the pregnant person and fetus, comprising hypertension assessment, and serial fetal ultrasound, including Doppler studies is then instituted, and may be combined with biochemical markers, such as Placental Growth Factor, for greater clinical precision. Recommendations on timing to deliver the growth-restricted fetus worldwide are converging, with similar guidance from clinical practice guidelines informed by high-quality Randomized Controlled Trials (RCTs) and large cohort studies. In most instances, it is reasonable to recommend delivery of all growth-restricted fetuses by approximately 38 weeks. Timing of delivery should take into consideration both short-term neonatal outcomes and long-term outcomes at school age. Mode of delivery is based on many factors, and induction of labor is a safe approach, especially after 34 weeks. Mechanical methods of induction may be preferred to pharmacologic methods, although both have a role and the choice of method is based on individualized assessment. Elective Cesarean birth thereby bypassing fetal stress during labor, is recommended in preterm growth-restricted fetuses with signs of adaptive fetal compromise, especially when ductus venosus flow is abnormal, or a contraction stress test is positive.