Characteristic/Demographic	EP Infants (≤28 wGA) (n = 4462)	VP Infants (>28 to <32 wGA) (n = 2904)	M-LP Infants (≥32 to <37 wGA) (n = 18 207)
Female, n (%)	2218 (49.7)	1344 (46.3)	8215 (45.1)
Race, n (%)
White	1694 (38.0)	1225 (42.2)	8369 (46.0)
Black	1450 (32.5)	823 (28.3)	3656 (20.1)
Other/multiracial	476 (10.7)	327 (11.3)	2206 (12.1)
Not reported	842 (18.9)	529 (18.2)	3976 (21.8)
State, n (%)
Iowa	830 (18.6)	657 (22.6)	6416 (35.2)
Kansas	568 (12.7)	411 (14.2)	2785 (15.3)
Mississippi	654 (14.7)	492 (16.9)	2340 (12.9)
Missouri	1283 (28.8)	798 (27.5)	3689 (20.3)
New Jersey	479 (10.7)	199 (6.9)	1175 (6.5)
Wisconsin	648 (14.5)	347 (11.9)	1802 (9.9)
Mean ± SD birth hospitalization LOS (days)	83.24 ± 36.92	48.82 ± 18.69	20.02 ± 16.62
Multiple birth, n (%)	870 (19.5)	671 (23.1)	3847 (21.1)
Delivery method, n (%)a
Cesarean	2648 (59.3)	1826 (62.9)	9577 (52.6)
Vaginal	1468 (32.9)	958 (33.0)	8174 (44.9)
Not reported	346 (7.8)	120 (4.1)	456 (2.5)
Mean ± SD follow-up duration (days)	725.92 (107.63)	745.34 (71.18)	744.73 (67.90)