Читать книгу Genetic Disorders and the Fetus - Группа авторов - Страница 17

The leading cause of infant death in the United States in 2014 was congenital malformations, deformations, and chromosomal abnormalities, accounting for 20.4 percent of 4,748 total infant deaths.¹³ Survival is clearly dependent on the severity or lethality of the congenital defect. The CDC assessed mortality rates for infants born with trisomy 13 and trisomy 18. The authors identified 5,515 infants born with trisomy 13 and 8,750 born with trisomy 18. The median age at death for both trisomy 13 and trisomy 18 was 10 days. Survival to at least 1 year occurred in 5.6 percent of those born with trisomy 13 or trisomy 18.¹⁰⁵ An international registry study (2019) from 18 countries revealed prevalence rates of 0.55 and 1.07 per 10,000 births for trisomies 13 and 18, respectively. Death in the first week of life occurred in 45 percent and 42 percent for trisomy 13 and trisomy 18, respectively. Reported mortality rates were 87 percent and 88 percent at 1 year for each of these trisomies.¹⁰⁶ A regional study in the Netherlands noted lethal congenital malformations in 51 percent of stillbirths and 70 percent among those who died during the neonatal period.¹⁰⁷ A Scottish study focusing on the survival of 6,153 infants with congenital anomalies up to the age of 5 years noted the following survival rates: chromosomal anomalies (48 percent), NTDs (72 percent), respiratory system anomalies (74 percent), congenital heart disease (75 percent), nervous system anomalies (77 percent) and Down syndrome (84 percent).¹⁰⁸ The survival rate among males with congenital defects was 84 percent, compared with 97 percent in those born unaffected.³⁰ Liu et al.¹⁰⁹ examined temporal changes in fetal and infant deaths caused by congenital malformations in Canada, England, Wales, and the United States. They concluded that the major factor responsible for the accelerated decline in infant deaths was prenatal diagnosis and elective abortion of fetuses with abnormalities. Given the frequency of Down syndrome, a more detailed discussion follows.