TABLE I.

Characteristics of Live Born Infants With Trisomy 13 and Trisomy 18 in Nine US States, 1999–2007 Birth Cohort

Characteristic	Trisomy 13		Trisomy 18
	Number births	Percent	Number births	Percent
Infant sex
Male	347	50.1	427	38.4
Female	340	49.1	681	61.2
Unknown	6	0.9	5	0.4
Gestational age
<32 weeks	122	17.6	206	18.5
32–36 weeks	223	32.2	277	24.9
≥37 weeks	336	48.5	605	54.4
Unknown	12	1.7	25	2.2
Plurality
Single	675	97.4	1,065	95.7
Multiple	15	2.2	41	3.7
Unknown	3	0.4	7	0.6
Maternal race/ethnicity
Non-Hispanic White	327	47.2	471	42.3
Non-Hispanic Black	110	15.9	208	18.7
Hispanic	217	31.3	366	32.9
Non-Hispanic Asian/PI	21	3.0	38	3.4
Other/unknown	18	2.6	30	2.7
Maternal age
<19 years	53	7.6	67	6.0
20–24 years	126	18.2	156	14.0
25–29 years	149	21.5	179	16.1
30–34 years	155	22.4	200	18.0
≥35 years	210	30.3	511	45.9
Geographic area
Metropolitan	618	89.2	991	89.0
Non-metropolitan	72	10.4	117	10.5
Unknown	3	0.4	5	0.4
State
Arizona	68	9.8	118	10.6
Colorado	52	7.5	59	5.3
Georgia	32	4.6	61	5.5
Illinois	63	9.1	127	11.4
Massachusetts	37	5.3	49	4.4
North Carolina	50	7.2	92	8.3
New Jersey	50	7.2	76	6.8
New York	85	12.3	127	11.4
Texas	256	36.9	404	36.3
Presence of heart defectsa
With heart defects	117	16.9	193	17.3
No heart defects	576	83.1	920	82.7
Presence of omphalocele
With omphalocele	52	7.5	58	5.2
No omphalocele	641	92.5	1,055	94.8
Birth period
1999–2002	264	38.1	400	35.9
2003–2007	429	61.9	713	64.1
Total	693	100.0	1,113	100.0

^aHeart defects include common truncus, transposition of great arteries, tetralogy of Fallot, atrioventricular septal defect, aortic valve stenosis, hypoplastic left heart syndrome, and coarctation of aorta.

PI, Pacific Islander.