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. Author manuscript; available in PMC: 2015 Jul 28.
Published in final edited form as: Am J Med Genet A. 2013 Nov 22;0(1):70–76. doi: 10.1002/ajmg.a.36247

TABLE I.

Prevalence Estimates of Trisomy 21 Among All Pregnancy Outcomes (Sum of Live Births, Fetal Deaths, Elective Terminations, and Unknown Outcomes *), Live Birth Prevalence of Trisomy 21, Unadjusted and Adjusted for Elective Termination, Presented by Maternal Race–Ethnicity and Age, Metropolitan Atlanta, 1996–2005

MACDP Five-County Region Non-Hispanic White Non-Hispanic Black Hispanic
All <35 ≥35 All <35 ≥35 All <35 ≥35 All <35 ≥35
Total live births, n 484,260a 407,786 76,474 184,473 143,426 41,047 186,274 163,638 22,636 77,473 71,319 6,154
Trisomy 21 all outcomes, n 790 356 434 386 141 245 243 120 123 104 70 34
Prevalenceb 16.3 8.7 26.8 21.0 9.8 59.7 13.0 7.3 54.3 13.4 9.8 55.3
95% CI 15.2–17.5 7.9–9.7 51.7–62.3 19.0–23.1 8.3–11.6 52.7–67.6 11.5–14.8 6.1–8.8 45.6–64.8 11.1–16.3 7.8–12.4 39.6–77.1
Prevalence ratio Referent Referent Referent 0.62c 0.74d 0.91 0.64c 1.0 0.93
95% CI 0.53–0.73 0.58–0.95 0.73–1.1 0.52–0.8 0.75–1.3 0.65–1.3
Trisomy 21 live births, n 559 286 273 243 105 138 189 98 91 93 63 30
Prevalenceb 11.5 7.0 36.0 13.2 7.3 33.6 10.2 6.0 40.2 12.0 8.8 48.7
95% CI 10.6–12.5 6.3–7.9 31.7–40.2 11.6–14.9 6.1–8.9 28.5–39.7 8.9–11.7 4.9–7.3 32.8–49.3 9.8–14.7 6.9–11.3 34.3–69.5
Prevalence ratio Referent Referent Referent 0.77e 0.81 1.2 0.91 1.2 1.5
95% CI 0.64–0.93 0.62–1.1 0.92–1.56 0.72–1.2 0.88–1.7 0.98–2.2
Trisomy 21 elective term, n 186 54 132 125 29 96 37 16 21 6 4 2
Adjusted prevalencef 14.4 8 48.5 18.2 8.9 50.8 11.6 6.7 47.0 12.5 9.3 52.0
95% CI 13.4–15.5 7.1–8.9 43.8–53.6 16.4–20.3 7.4–10.5 44.4–58.2 10.2–13.3 5.6–8.1 39.1–57.1 10.3–15.3 7.3–11.8 36.9–73.3
Prevalence ratio Referent Referent Referent 0.64g 0.76h 0.92 0.69g 1.0 1.0
95% CI 0.54–0.76 0.59–0.98 0.74–1.2 0.55–0.86 0.78–1.4 0.73–1.5

CI, confidence interval.

*

Pregnancies diagnosed prenatally with trisomy 21 for which a delivery record was not found at the MACDP ascertainment sources.

a

Total number of live births in the Metropolitan Atlanta Congenital Defects Program (MACDP), including those of other race-ethnicities.

b

Prevalence per 10,000 live births in the MACDP region.

c

Statistically significant difference compared with all birth outcomes among all non-Hispanic white mothers (P < 0.0001).

d

Statistically significant difference compared with all birth outcomes among non-Hispanic white mothers aged <35 years (P < 0.05).

e

Statistically significant difference compared with unadjusted live birth prevalence among all non-Hispanic white mothers (P <0.01).

f

Prevalence per 10,000 live births in the Metropolitan Atlanta Congenital Defects Program region adjusted for 74% survival of trisomy 21 elective terminations [adjusted live births = live births + (elective terminations × 0.74)].

g

Statistically significant difference compared with adjusted live birth prevalence among all non-Hispanic white mothers (P ≤ 0.001).

h

Statistically significant difference compared with adjusted live birth prevalence among non-Hispanic white mothers aged <35 years (P < 0.05).