The natural history of anencephaly

Objective: Early elective termination of pregnancy is the most common outcome of a diagnosis of anencephaly in developed countries. Experience and expertise with management of ongoing pregnancies is limited. We aimed to investigate the natural history of these pregnancies from diagnosis to delivery and to determine timing of death.

Method: A retrospective review of cases of anencephaly diagnosed between 2003 and 2009 in tertiary-referral university teaching hospitals in Cork.

Results: The majority of cases (25/26; 96%) were diagnosed prenatally at a median gestation of 21(+2) weeks (range 13(+4)-32(+4)). The median maternal age was 30 years (range 17-41) and 50% were primigravidae. Seven pregnancies were complicated by polyhydramnios and four deliveries were complicated by shoulder dystocia. The median gestation at delivery was 35 weeks (range 22(+5)-42(+6)); 69% of labours were induced at a median gestation of 34 weeks. Six women (6/26; 23%) had a pre-labour intrauterine fetal death and nine women (9/26; 35%) had an intrapartum fetal death. Median neonatal survival time was 55 min (range 10 min to 8 days). Six parents donated neonatal organs for transplantation.

Conclusion: This study provides useful information for health professionals caring for patients with a diagnosis of anencephaly. The majority of these infants die prior to delivery but short-term survival is possible.