| The aim of the study is to determine the prevalence, outcomes, and survival (among
live births [LB]), in pregnancies diagnosed with trisomy 13 (T13) and 18 (T18), by congenital
anomaly register and region. Twenty-four population- and hospital-based birth
defects surveillance registers from 18 countries, contributed data on T13 and T18
between 1974 and 2014 using a common data-reporting protocol. The mean total
birth prevalence (i.e., LB, stillbirths, and elective termination of pregnancy for fetal
anomalies [ETOPFA]) in the registers with ETOPFA (n = 15) for T13 was 1.68 (95% CI
1.3–2.06), and for T18 was 4.08 (95% CI 3.01–5.15), per 10,000 births. The prevalence
varied among the various registers. The mean prevalence among LB in all registers
for T13 was 0.55 (95%CI 0.38–0.72), and for T18 was 1.07 (95% CI 0.77–1.38),
per 10,000 births. The median mortality in the first week of life was 48% for T13 and
42% for T18, across all registers, half of which occurred on the first day of life. Across
16 registers with complete 1-year follow-up, mortality in first year of life was 87% for
T13 and 88% for T18. This study provides an international perspective on prevalence
and mortality of T13 and T18. Overall outcomes and survival among LB were poor
with about half of live born infants not surviving first week of life; nevertheless about
10% survived the first year of life. Prevalence and outcomes varied by country and
termination policies. The study highlights the variation in screening, data collection,
and reporting practices for these conditions. |