Table 1.

Maternal and Child Characteristics by Asthma Status in the Collaborative Perinatal Project, United States, 1959–1965

Characteristic	Nonasthma (n = 27,293)		Asthma (n = 1,514)		P Valuea
	No.	%	No.	%
Maternal race					<0.01
White	14,018	51.4	645	42.6
Black	12,323	45.2	785	51.9
Other	952	3.5	84	5.6
Maternal age, years					0.33
<20	5,998	22.0	351	23.2
20–29	15,767	57.8	838	55.4
30–39	5,046	18.5	297	19.6
≥40	482	1.8	28	1.9
Married at pregnancy	21,485	78.7	1,151	76.0	0.04
Maternal education					0.34
Less than high school	7,455	27.3	439	29.0
High school	16,344	59.9	890	58.8
College and above	3,494	12.8	185	12.2
Smoking during pregnancy					0.27
Nonsmoker (0 cigarettes/day)	14,824	54.3	810	53.5
Light smoker (1–9 cigarettes/day)	7,878	28.9	456	30.1
Heavy smoker (≥10 cigarettes/day)	4,425	16.2	244	16.1
Maternal allergic diseases	3,039	11.1	203	13.4	<0.01
Parity					0.09
0	7,921	29.0	469	31.0
1	6,118	22.4	355	23.5
≥2	13,199	48.4	685	45.2
Mode of delivery					0.58
Vaginal	25,363	92.9	1,407	92.9
Assisted vaginal	548	2.0	35	2.3
Cesarean	1,361	5.0	72	4.8
Birthweight, g					0.44
2,500–2,999	6,945	25.5	389	25.7
3,000–3,499	12,221	44.8	701	46.3
3,500–3,999	6,469	23.7	332	21.9
≥4,000	1,658	6.1	92	6.1
Gestational age, weeks					0.13
37	1,646	6.0	104	6.9
38	3,040	11.1	194	12.8
39	5,400	19.8	314	20.7
40	6,860	25.1	338	22.3
41	5,421	19.9	305	20.3
42	2,922	10.7	151	10.0
43	1,306	4.8	71	4.7
44	698	2.6	37	2.4
Male sex	13,785	50.5	975	64.4	<0.01
Apgar score of 0–6 at 5 minutes	851	3.1	47	3.1	0.80
Breastfeeding	4,766	17.5	243	16.1	0.25
Indirect Coombs’ test positiveb	713	2.6	44	2.9	0.78
Exchange transfusionc	251	0.9	15	1.0	0.77

^a P values were determined by χ² test.

^b Indirect Coombs’ test positive detects antibodies against red blood cells that are present unbound in the patient's serum.

^c Medical treatment in which apheresis is used to remove patient's red blood cells or platelets and replace them with transfused blood products.