Fifty consecutive obstetric cases have been analyzed in which there was a clear history of either vigorous or reduced fetal activity during the week preceding delivery resulting in the birth of an infant weighing 2.5 kg or less after the 37th week. Especially in such hypertensive pregnancies, a maternal history of reduced overall fetal activity is very suggestive of impending fetal death, while a history of vigorous fetal activity tends to denote that the fetus is in no immediate danger. A plea is made for a greater awareness of this economical “test” of fetal well-being. It is suggested that in some circumstances both impaired fetal growth and reduced fetal activity may be teleologic adaptations to the threat of a negative energy balance.