Demographic Characteristics	Total Infants with HRF/PPHN (n=918)	Infants with HRF/PPHN
		Preterm infants (n=504)	T/NT infants (n=414)	P-value
Sex, n (%)
Male	542 (59.0)	299 (59.3)	243 (58.7)	0.8469
Female	375 (40.9)	205 (40.7)	170 (41.4)	0.9052
Unknown	1 (0.1)	0 (0.0)	1 (0.2)	0.2696
Clinical Characteristics, n (%)
Single liveborn in-hospital born with Cesarean section	360 (39.2)	211 (41.9)	149 (36.0)	0.0697
Respiratory distress syndrome	493 (53.7)	350 (69.4)	143 (34.5)	<0.0001
Patent ductus arteriosus	460 (50.1)	265 (52.6)	195 (47.1)	0.0986
Neonatal jaundice due to preterm delivery	383 (41.7)	279 (55.4)	104 (25.1)	<0.0001
Septicemia (sepsis) of newborn	371 (40.4)	206 (40.9)	165 (39.9)	0.7545
Secundum atrial septal defect	380 (41.4)	202 (40.1)	178 (43.0)	0.3721
Other specific conditions in perinatal period	326 (35.5)	171 (33.9)	155 (37.4)	0.2687
Anemia of prematurity	322 (35.1)	248 (49.2)	74 (17.9)	<0.0001
Respiratory failure of newborn	268 (29.2)	111 (22.0)	157 (37.9)	<0.0001
Neonatal thrombocytopenia	265 (28.9)	155 (30.8)	110 (26.6)	0.1639
Provider Characteristics
US Geographic region, n (%)
Northeastern region	95 (10.4)	64 (12.7)	31 (7.5)	0.0099
Midwestern region	94 (10.2)	45 (8.9)	49 (11.8)	0.1483
Southern region	606 (66.0)	334 (66.3)	272 (65.7)	0.8562
Western region	123 (13.4)	61 (12.1)	62 (15.0)	0.2036
Bed size group, n (%)
<100 beds	22 (2.4)	14 (2.8)	8 (1.9)	0.4046
100-199 beds	81 (8.8)	42 (8.3)	39 (9.4)	0.5634
200-299 beds	53 (5.8)	36 (7.1)	17 (4.1)	0.0497
300-499 beds	239 (26.0)	125 (24.8)	114 (27.5)	0.3475
≥500 beds	481 (52.4)	263 (52.2)	218 (52.7)	0.8861
Unknown	42 (4.6)	24 (4.8)	18 (4.3)	0.7651
Teaching status, n (%)
Major teaching	461 (50.2)	244 (48.4)	217 (52.4)	0.2275
Non-teaching	215 (23.4)	136 (27.0)	79 (19.1)	0.0049
Minor teaching	200 (21.8)	100 (19.8)	100 (24.2)	0.1152
Unknown	42 (4.6)	24 (4.8)	18 (4.3)	0.7651
Urban/rural status, n (%)
Urban	873 (95.1)	480 (95.2)	393 (94.9)	0.8283
Rural	3 (0.3)	0 (0.0)	3 (0.7)	0.0556
Unknown	42 (4.6)	24 (4.8)	18 (4.3)	0.7651