Table 1.

Clinical Characteristics of the cohort with and without RDS.

Variables	No RDS (n = 458)	RDS (n = 477)	P-value
Gestational age (weeks): median (IQR)	33 (31, 35)	30 (26, 34)	<0.001*
Sex: n (%)
Female	236 (51)	198 (41)	0.02*
Male	220 (48)	277 (58)
Race: n (%)
Non-Hispanic white	328 (71)	343 (72)
Non-Hispanic black	64 (14)	82 (17)	0.09
Hispanic	20 (4)	25 (5)
Asian-pacific islander	23 (5)	13 (2)
Other/mixed parents	22 (4)	13 (2)
Infant birth weight (g) ± SD	1,818 ± 515	1,474 ± 606	<0.001*
Preterm labor: n (%)
Absent	64 (14)	74 (15)	0.36
Present	203 (44)	196 (41)
Maternal diabetes mellitus: n (%)
No	419 (92)	412 (94)	0.27
Yes	33 (7)	21 (5)
Chorioamnionitis: n (%)
No	161 (35)	204 (43)	0.26
Yes	35 (8)	33 (7)
Antenatal steroid: n (%)
No	1 (0.6%)	16 (3%)	0.0003*
Yes	280 (61%)	273 (57%)
Surfactant use: n (%)
No	448 (97)	167 (35)	<0.001*
Yes	8 (2)	305 (64)
Chronic lung disease: n (%)
No	297 (65)	238 (50)	<0.001*
Yes	16 (4)	92 (20)

^*The infants with RDS had younger gestational age at birth, lower birth weight, predominantly male, and had increased use of surfactant and higher incidence of chronic lung disease^**.

The two groups (RDS, no RDS) did not differ in race, incidence of preterm labor, maternal diabetes mellitus, chorioamnionitis^***.

^**Chronic lung disease included infants treated with oxygen at 28 days of life or at 36 weeks postmenstrual age (48).

^***Chorioamnionitis is diagnosed based on clinical features such as maternal fever (49).