Background: The clinical presentations and survival patterns of infants with trisomy 18 have changed with increasing utilization of prenatal ultrasound and amniocentesis, and improvements in neonatal intensive care.
Methods: We obtained data on duration of survival, male to female ratio, and clinical details for patients with trisomy 18, and calculated the prevalence rate.
Results: We studied 31 consecutive trisomy 18 infants. The estimated prevalence was 1/4, 144. Eleven (35%) were premature infants, and 20 (65%) were full term. Mean birth weight was 1896 g. Median life expectancy was 12 days; 11 days for males and 14 days for females (p = 0.87). The short-term survival rates of 1 week, 4 weeks, and 6 months were 58%, 32%, and 10%, respectively. The long-term survival rates of 1 year, 2 years, and 3 years were 6%, 6%, and 3%, respectively. Families signed do-not-resuscitate consent forms for five male (50%) and 19 female infants (90%) (p = 0.043).
Conclusion: All trisomy 18 infants in this study were preterm or full-term deliveries. Mean birth weight was lower than previously reported, and a high percentage of families signed do-not-resuscitate consent forms. Females did not survive longer than males, due to more females not being resuscitated. Most infants died in the first few weeks of life, but 3-6% of infants lived for 21 year. The possibility of long-term survival should be considered when counseling parents regarding trisomy 18.