Development and Maturation of the Immune System in Preterm Neonates: Results from a Whole Genome Expression Study

Table 1

Comparison of selected demographic data in the studied cohorts.

	Extremely preterm (23–26 weeks) (𝑛=41)	Very preterm (27–29 weeks) (𝑛=39)	Moderately preterm (30–32 weeks) (𝑛=33)	𝑃
Birth weight, g (𝑥±SD)	727±124	1149±207	1245±211	<0.001^a
Gestational age (weeks) (𝑥±SD)	25.0±1.1	28.2±0.8	30.7±0.8	<0.001^a
Male gender	24 (58%)	20 (51%)	17 (52%)	0.76^b
Vaginal delivery/Cesarean section	20/21	15/24	8/25	0.01^b
Multiple pregnancy	4 (10%)	8 (20%)	6 (18%)	0.56^b
Small-for-gestational-age infant	4 (10%)	1 (2%)	5 (15%)	0.1^b
Maternal hypertension	8 (19%)	7 (18%)	2 (8%)	0.74^b
Maternal diabetes	3 (7%)	2 (5%)	0	0.79^b
Maternal fever/infection prior to delivery	5 (12%)	6 (15%)	4 (13%)	0.8^b
1st minute Apgar score (Me; 25–75th percentile)	2 (1–4)	5 (4–6)	5 (2–6)	0.01^c
5th minute Apgar score (Me; 25–75th percentile)	6 (4–6)	7 (6-7)	7 (6–8)	0.001^c
Delivery room intubation	28 (69%)	16 (40%)	11 (33%)	0.01^b
Surfactant therapy	33 (81%)	29 (73%)	14 (43%)	0.003^b
Initial a/A ratio	0.31±0.2	0.25±0.13	0.44±0.25	0.01^a
Prenatal steroids	10 (25%)	12 (29%)	22 (66%)	0.01^b
Ureaplasma infection	12 (29%)	8 (21%)	6 (18%)	0.28^b
Pharmacological closure of patent ductus arteriosus	22 (54%)	23 (59%)	11 (33%)	0.08^b
Surgical closure of patent ductus arteriosus	18 (44%)	4 (10%)	2 (6%)	<0.001^b
Length of mechanical ventilation (Me; 25–75th percentile)	42 (25–52)	3 (1–10)	2 (0–6)	<0.001^c
Bronchopulmonary dysplasia	40 (98%)	24 (62%)	6 (18%)	<0.001^b

^a𝑃 value for one-way analysis of variance.
^b𝑃 value for chi-square test.
^c𝑃 value for Kruskal-Wallis analysis of variance.