Distribution of 18-24 months of corrected age (CA) and three growth parameters of VLBW infants
Head circumference, body weight, and height growth states at 18-24 months of CA are shown in Table 1. Most (81.4%, 206/253) VLBW infants caught up their head growths at 18-24 months of CA. Infants in the no catch-up (NCU) group had smaller head circumferences, shorter heights, and less body weights than those in the catch-up (CU) group (head circumference: 44.6 cm vs. 47.2 cm; height: 81.0 cm. vs. 83.8 cm; body weight: 9.7 kg vs. 11.2 kg). These differences were all statistically significant (P < 0.001). Among the three parameters (head circumference, body weight, and height growth), head circumference had the biggest difference between the two groups. It decreased from birth to discharge. However, it increased from discharge to 18-24 months of CA (1.6cm, 0.4cm, and 2.6 cm at birth, discharge, and 18-24 months of CA, respectively) (Appendix 1).
Table 1. Distribution of 18-24 month of CA catch-up status and three growth parameters in VLBW infants
|
CU
|
NCU
|
Total
|
P value
|
N(%)
|
M ± SD
|
N(%)
|
M ± SD
|
M ± SD (cm)
|
HC
|
206 (81.4)
|
47.2 ± 3.5
|
47 (18.6)
|
44.6 ± 1.0
|
46.7 ± 3.4
|
<0.001***
|
HT
|
|
83.8 ± 4.1
|
|
81.0 ± 3.5
|
83.3 ± 4.2
|
<0.001***
|
WT
|
|
11.2 ± 1.4
|
|
9.7 ± 1.0
|
10.9 ± 1.4
|
<0.001***
|
Abbreviations: CA, Corrected age; CU, Catch-up group; HC, Head circumference; HT, Height; M±SD, Mean±Standard deviations; NCU, No catch-up group; WT, Weight
*** P<0.001 compared with CU
By independent T-test
Comparison of demographic and perinatal characteristics between CU and NCU groups of VLBW infants
Demographic and perinatal characteristics of VLBW infants according to catch-up status are shown in Table 2. Rates of microcephaly, intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), sepsis, necrotizing enterocolitis (NEC), cerebral palsy, length of NICU stay, ventilation care, and parenteral nutrition were significantly greater in the NCU group (microcephaly: 27.7% (13/47) vs. 14.1% (29/206), P = 0.015; IVH: 53.2% (25/47) vs. 31.6% (65/206), P = 0.005; BPD: 68.1% (32/47) vs. 30.6% (63/206), P < 0.001; sepsis: 31.9% (15/47) vs. 17.0% (35/206), P = 0.021; NEC: 17.0% (8/47) vs. 3.9% (8/206), P < 0.001; NICU stay: 90.6 vs. 74.3, P = 0.002; ventilator care: 27.4 vs. 11.9, P < 0.001; parenteral nutrition: 40.6 vs. 25.6, P < 0.001). Birth weight (BW), rate of low maternal education, and rate of nursery use were significantly lower in the NCU group (BW: 929.9g vs. 1084.9g, P < 0.001; low maternal education: 6.4% (3/47) vs. 19.4% (40/206), P = 0.032; nursery use: 21.3% (10/47) vs. 37.9% (78/206), P = 0.031).
Table 2. Comparison of demographic and perinatal characteristics between the CU and NCU groups of VLBW infants
|
CU
(N=206)
|
NCU
(N=47)
|
P
value
|
GA (wk)
|
27.9 ± 2.0
|
27.7 ± 2.1
|
0.466
|
BW (g)
|
1084.9 ±239.1
|
929.9 ± 264.4
|
<0.001***
|
SGA, n (%)
|
60 (29.1)
|
20 (42.6)
|
0.075
|
Male sex, n (%)
|
95 (46.1)
|
28 (59.6)
|
0.097
|
Multiple pregnancy, n(%)
|
72 (35.0)
|
16 (34.0)
|
0.906
|
Maternal age (y)
|
33.0 ± 4.0
|
34.2 ± 3.8
|
0.052
|
Cesarean section, n(%)
|
131 (63.6)
|
36 (76.6)
|
0.090
|
GDM/overt DM, n (%)
|
13 (6.3)
|
6 (12.8)
|
0.131
|
PIH/chronic HTN, n (%)
|
46 (22.3)
|
10 (21.3)
|
0.876
|
PROM, n (%)
|
91 (44.2)
|
19 (40.4)
|
0.641
|
1-min Apgar score
|
4.3 ± 2.0
|
3.9 ± 1.9
|
0.223
|
5-min Apgar score
|
6.6 ± 1.9
|
6.4 ± 1.5
|
0.438
|
Microcephaly, n (%)
|
29 (14.1)
|
13 (27.7)
|
0.014*
|
Neonatal resuscitation, n (%)
|
185 (89.8)
|
43 (91.5)
|
0.728
|
Length of stay in NICU (days)
|
74.3 ± 32.1
|
90.6 ±39.4
|
0.003**
|
Ventilator care (days)
|
11.9 ± 21.2
|
27.4 ± 26.0
|
<0.001***
|
Oxygen therapy (days)
|
8.8 ± 10.9
|
12.9 ± 14.9
|
0.032*
|
Parenteral nutrition(days)
|
25.6 ± 19.5
|
40.6 ± 25.5
|
<0.001***
|
RDS, n (%)
|
164 (79.6)
|
38 (80.9)
|
0.849
|
IVH, n (%)
|
65 (31.6)
|
25 (53.2)
|
0.005**
|
BPD, n (%)
|
63 (30.6)
|
32 (68.1)
|
<0.001***
|
PVL, n (%)
|
12 (5.8)
|
6 (12.8)
|
0.096
|
PDA, n (%)
|
72 (35.0)
|
22 (46.8)
|
0.130
|
Sepsis, n (%)
|
35 (17.0)
|
15 (31.9)
|
0.020*
|
NEC, n (%)
|
8 (3.9)
|
8 (17.0)
|
<0.001***
|
ROP, n (%)
|
22 (10.7)
|
6( 12.8)
|
0.682
|
Non parental caregiver, n (%)
|
7 (3.4)
|
2 (4.3)
|
0.776
|
Low maternal education, n (%)
|
40 (19.4)
|
3 (6.4)
|
0.032*
|
Nursery use, n(%)
|
78 (37.9)
|
10 (21.3)
|
0.031*
|
Language therapy, n (%)
|
6 (2.9)
|
4 (8.5)
|
0.076
|
Abbreviations: BW, Birth weight; BPD, Bronchopulmonary dysplasia; CU, Catch-up group; DM; Diabetes mellitus; GA, Gestational age; GDM, Gestational diabetes mellitus; HTN, Hypertension; IVH, Intraventricular hemorrhage; NCU, No catch-up group; NEC, Necrotizing Enterocolitis; PDA, Patent ductus arteriosus; PIH, Pregnancy induced hypertension; PROM, Premature rupture of membranes; PVL. Periventricular leukomalacia; RDS, Respiratory distress syndrome; ROP, Retinopathy of Prematurity; SGA, Small for gestational age.
*P<0.05 compared with CU
** P<0.01 compared with CU
*** P<0.001 compared with CU
By independent T-test
Correlations between clinical factors and catch-up status of VLBW infants at 18-24 months of CA
After adjusting for three factors (GA, birth weight, and birth head circumference), only IVH, BPD, sepsis, NEC status, length of ventilator care, and parenteral nutrition were significantly associated with catch-up status. BPD status was the most significant clinical factor affecting catch-up head growth (adjusted OR 4.586, 95% CI 1.960-10.729) (Table 3).
Table 3. Correlations between clinical factors and catch-up status of VLBW infants at 18-24 months of CA
|
OR
(95% CI)
|
P
value
|
aOR†
(95% CI)
|
P
value
|
Length of stay in NICU (days)
|
1.012
(1.003-1.022)
|
0.008**
|
1.011
(0.999-1.024)
|
0.070
|
Ventilator care (days)
|
1.025
(1.012-1.038)
|
<0.001***
|
1.028
(1.010-1.046)
|
0.002**
|
Oxygen therapy (days)
|
1.026
(1.002-1.052)
|
0.037*
|
1.012
(0.984-1.041)
|
0.398
|
Parenteral nutrition(days)
|
1.029
(1.015-1.044)
|
<0.001***
|
1.031
(1.013-1.048)
|
<0.001***
|
IVH, n (%)
|
2.465
(1.295-4.693)
|
0.006**
|
2.403
(1.138-5..075)
|
0.021*
|
BPD, n (%)
|
4.842
(2.450-9.569)
|
<0.001***
|
4.586
(1.960-10.729)
|
<0.001***
|
Sepsis, n (%)
|
2.290
(1.123-4.672)
|
0.023*
|
2.380
(1.054-5.371)
|
0.037*
|
NEC, n (%)
|
5.077
(1.797-14.341)
|
0.002**
|
4.187
(1.207-14.522)
|
0.024*
|
Abbreviations: aOR, adjusted odds ratio; BPD, Bronchopulmonary dysplasia; IVH, Intraventricular hemorrhage; NEC, Necrotizing Enterocolitis; OR, Odds ratio.
†Adjusted for Gestational age, Birth weight, and Birth head circumference
*P<0.05
** P<0.01
*** P<0.001
By multiple logistic regression analysis
Comparison of developmental outcomes between CU and NCU groups of VLBW infants at 18-24 months of CA
At 18-24 months of CA, the NCU group exhibited lower developmental indices and higher rate of developmental delay than the CU group (language developmental index: 92.7 ± 14.5 vs. 96.9 ± 15.3, P=0.090, cognitive developmental index: 91.8 ± 14.8 vs. 100.5 ± 14.3, P<0.001, motor developmental index: 89.7 ± 17.5 vs. 99.1 ±12.8, P<0.001, respectively). Motor developmental delay was the most significantly relevant factor associated with catch-up head growth. The motor development index difference between two groups was only statistically significant after adjusting for four major neonatal morbidities: IVH, BPD, sepsis and NEC status (adjusted OR 10.727, 95% CI 1.922-59.868) (Table 4).
Table 4. Comparison of developmental outcomes between CU and NCU groups of VLBW infants at 18-24 months of CA
|
CU
(N=206)
|
NCU
(N=47)
|
P
value
|
OR
(95% CI)
|
P
value
|
aOR
(95% CI)
|
P
value
|
LDI, M ± SD (points)
|
96.9 ± 15.3
|
92.7 ± 14.5
|
0.090
|
|
|
|
|
Developmental delay, n (%)
|
6 (2.9)
|
4 (8.5)
|
0.076
|
3.101
(0.839-11.462)
|
0.986
|
1.364
(0.300-6.195)
|
0.688
|
CDI, M ± SD (points),
|
100.5 ± 14.3
|
91.8 ± 14.8
|
<0.001***
|
|
|
|
|
Developmental delay, n (%)
|
6 (2.9)
|
6 (12.8)
|
0.004**
|
4.878
(1.498-15.882)
|
0.748
|
2.294
(0.629-8.373)
|
0.209
|
MDI, M ± SD (points),
|
99.1 ± 12.8
|
89.7 ± 17.5
|
<0.001***
|
|
|
|
|
Developmental delay, n (%)
|
2 (1.0)
|
7 (14.9)
|
<0.001***
|
17.850
(3.577-89.086)
|
0.013*
|
10.727
(1.922-59.868)
|
0.007**
|
Abbreviations: CDI, Cognitive developmental index; CU, Catch-up group; NCU, No catch-up group; LDI, Language developmental index; MDI, Motor developmental index; M±SD, Mean±Standard deviations; OR, Odds ratio.
†Adjusted for IVH, BPD, sepsis and NEC status
*P<0.05 compared with CU
** P<0.01 compared with CU
*** P<0.001 compared with CU
By independent T-test
By multiple logistic regression analysis