Limb and Holmes (1994) documented that prenatal diagnosis and the availability of elective termination of pregnancy
have significantly altered the birth status of infants with anencephaly.
They identified 175 affected stillborn and liveborn
infants as well as elective second-trimester terminations with anencephaly.
In the 1970s, half the infants with
anencephaly were born alive at an average gestational age of 35.6 weeks. By 1988 to 1990, all affected infants were
diagnosed by maternal serum a-fetoprotein screening or prenatal sonography.
All parents elected to terminate, at an
average gestational age of 19.6 weeks. These investigators, however, commented that their study population was
potentially biased due to a higher percentage of mothers with epilepsy and diabetes delivering at their institution.