The Principles of Clinical Cytogenetics - Extra Materials - Springer

Prenatal Cytogenetics 271
Table 2
Maternal Age-Specific Rates (%) for Chromosome Abnormalities
From liveborn studies a From amniocenteses From CVS
Maternal All All All
age chromosome chromosome chromosome
(year) 47,+21 b 47,+21 c abnormalities b 47,+21 b 47,+21 c abnormalities b 47,+21 c abnormalities d
33 0.16 — 0.29 0.24 — 0.48 — —
34 0.20 — 0.36 0.30 — 0.66 — —
35 0.26 — 0.49 0.40 — 0.76 — 0.78
36 0.33 0.35 0.60 0.52 0.31 0.95 0.42 0.80
37 0.44 0.43 0.77 0.67 0.80 1.20 0.68 2.58
38 0.57 0.42 0.97 0.87 0.73 1.54 0.45 3.82
39 0.73 0.79 1.23 1.12 0.84 1.89 2.05 2.67
40 0.94 1.21 1.59 1.45 1.03 2.50 1.20 3.40
41 1.23 2.67 2.00 1.89 1.50 3.23 3.12 6.11
42 1.56 4.28 2.56 2.44 2.92 4.00 2.88 8.05
43 2.00 1.82 3.33 3.23 3.05 5.26 1.20 5.15
44 2.63 — 4.17 4.00 1.52 6.67 2.63 10.00
45 3.33 — 5.26 5.26 2.50 8.33 8.33 7.14
a Estimated liveborn statistics (33).
b Data compiled from 19,675 genetic amniocenteses (33).
c Data compiled from 3041 CVS, 7504 amniocenteses, and 13,139 with no test (35). These are observed prevalences.
d Data compiled by Hsu (30).
Table 3
Fetal Deaths Subsequent to Amniocentesis
Stillbirths and Neonatal Deaths
Fetal deaths
Proportion 95% confidence
Abnormalities Number (%) interval (%)
47,+21 73 30.1 19.0–42.0
47,+18 25 68.0 46.5–85.1
47,+13 7 42.9 9.9–81.6
47,XXX 39 0.0 0.0–9.0
47,XXY 37 8.1 0.8–11.0
47,XYY 33 3.0 0.08–15.8
45,X 12 75.0 42.8–94.5
45,X/46,XX 19 10.5 1.3–33.1
Balanced translocations and inversions 71 2.8 0.3–9.8
Markers, variants, fragments 27 0.0 0.0–12.8
Note: Proportion refers to the number of fetal losses compared to the total number of
fetuses diagnosed with the given abnormality.
Source: ref. 34.
Fetal loss from 28 weeks on in pregnancy is defined as stillbirth, and neonatal death refers to death
occurring within the first 4 weeks after birth. Chromosome studies in such cases have shown that the
incidence of chromosome abnormality is about 10 times that in the rest of the population. Combining