Table 12:
Estimated Prevalence of Chromosomal Anomalies at 12 Weeks of Pregnancy
| Chromosomal Anomaly | N (95% CrI) per 10,000 Pregnant People, First Trimester (12 weeks) | N (95% CrI) per 10,000 Pregnant People, Second Trimester (18 weeks) | Sources |
|---|---|---|---|
| Autosomal Trisomies (Overall and by Maternal Age) | |||
| Trisomy 21 (overall)a | 23.9 (18.9–30.6) | 18.1 (14.2–23.1) | BORN, 2016; Savva et al, 2010; Morris et al, 199982,84,85 |
| < 20 years old | 11.8 (2.9–24.2) | 8.9 (2.2–18.3) | |
| 20–24 years old | 12.1 (7.1–18.6) | 9.1 (5.4–14.0) | |
| 25–29 years old | 13.4 (9.2–18.5) | 10.1 (6.9–13.9) | |
| 30–34 years old | 19.8 (14.7–25.8) | 15.0 (11.1–19.5) | |
| 35–39 years old | 55.2 (41.9–72.6) | 41.7 (31.6–54.8) | |
| Trisomy 18 (overall)a | 8.4 (5.4–12.7) | 6.9 (4.4–10.4) | BORN, 2016; Savva et al, 2010; Morris et al, 200882,84,86 |
| < 20 years old | 4.0 (0–12.2) | 3.2 (0–10.0) | |
| 20–24 years old | 4.1 (1.2–7.9) | 3.3 (1.0–6.5) | |
| 25–29 years old | 4.5 (2.2–7.7) | 3.7 (1.8–6.3) | |
| 30–34 years old | 6.5 (3.7–10.4) | 5.3 (3.1–8.5) | |
| 35–39 years old | 20.8 (12.7–32.0) | 17.0 (10.4–26.1) | |
| Trisomy 13 (overall)a | 3.0 (1.7–5.1) | 2.7 (1.5–4.6) | BORN, 2016; Savva et al, 2010; Morris et al, 200882,84,86 |
| < 20 years old | 1.5 (0–6.1) | 1.3 (0–5.5) | |
| 20–24 years old | 1.5 (0–4.1) | 1.3 (0–3.7) | |
| 25–29 years old | 1.7 (0.5–3.4) | 1.5 (0.4–3.1) | |
| 30–34 years old | 2.4 (1.1–4.5) | 2.2 (1.0–4.1) | |
| 35–39 years old | 7.1 (3.5–12.8) | 6.4 (3.1–11.5) | |
| Expected Sex Chromosome Aneuploidiesb | |||
| Monosomy X (45,X) | 13.0 per 10,000 female fetuses | NA | Viuff et al, 2015; Gravholt et al, 199687,88 |
| Triple X syndrome | 10.0 per 10,000 female fetuses | NA | Viuff et al, 2015; Tartaglia et al, 201087,89 |
| XXY syndrome (47,XXY) | 15.3 per 10,000 male fetuses | NA | Bojesen et al, 200390 |
| XYY syndrome | 10.0 per 10,000 male fetuses | NA | Viuff et al, 2015; Stochholm et al, 201287,91 |
| Detected Sex Chromosome Aneuploidiesb | |||
| Monosomy X (45,X) | 6.28 per 10,000 female fetuses | NA | European Registry92 |
| Triple X syndrome | 1.6 per 10,000 female fetuses | NA | Viuff et al, 2015; Tartaglia et al, 201087,89 |
| XXY syndrome (47,XXY) | 1.94 per 10,000 male fetuses | NA | European Registry92 |
| XYY syndrome | 0.5 per 10,000 male fetuses | NA | Viuff et al, 2015; Stochholm et al, 201287,91 |
| Microdeletion Syndromes | |||
| 22q11.2 deletion syndrome | 10.0 | NA | McDonald-McGinn et al, 201593 |
Abbreviations: BORN, Better Outcomes Registry and Network; CrI: credible interval; NA, not applicable.
a
Overall prevalence for pregnant people < 40 years old. Age distribution is based on BORN data from 2014 to 2016.82
b
The expected prevalence can be thought of as the “true” prevalence based on screening and subsequent confirmatory diagnostic testing. Because of the possible underdiagnosis and underreporting of sex chromosome aneuploidies, the expected prevalence is higher than the detected prevalence.