Growth from Birth to NICU Discharge
Six hundred and twenty-nine infants met criteria for this secondary analysis. Maternal and child characteristics for infants with length growth failure, normal growth, and accelerated growth are shown in Table 1. Maternal and child characteristics for infants with weight growth failure, normal growth, and accelerated growth are shown in Supplementary Table 1. Common co-morbidities of prematurity including necrotizing enterocolitis (stage 2b or 3), severe ICH, severe bronchopulmonary dysplasia (BPD), symptomatic culture positive sepsis, and length of stay are included. The linear growth failure group had more mothers with a high school education or less and infants born at a lower gestational age (Table 1). The weight growth failure group were less likely to be small for gestational age at birth (Supplementary Table 1).
Table 1. Cohort subject characteristics during the timeframe of birth to hospital discharge. Growth failure and accelerated growth is defined as having length growth failure or accelerated length growth at discharge. Categorical variables are represented by n (%). Continuous variables are represented with mean (SD) or median (IQR). P-values were calculated with Chi-squared tests for categorical and ANOVA for continuous variables. Severe NEC was defined as Bell’s stage 2b to 3. Severe ICH was defined as grade III or IV either unilateral or bilateral, according to Papile staging. BPD was defined as requiring nasal canula or higher levels of respiratory support at 36 weeks PMA. Severe sepsis was defined as culture-proven bacterial or fungal sepsis resulting in blood-pressure support or substantive new respiratory support.
|
Length Growth Failure, n (%) or median (IQR)
|
Normal Length Growth, n (%) or median (IQR)
|
Accelerated Length Growth, n (%) or median (IQR)
|
p-value
|
Included Infants (n=629 )
|
371
|
228
|
30
|
-
|
Maternal Characteristics
|
Maternal age
|
28.6 (6.1)
|
29.8 (6.3)
|
30.7 (5.7)
|
0.02
|
Maternal education
|
|
|
|
|
High School or less
|
133 (35.8)
|
58 (25.4)
|
7 (23.3)
|
0.01
|
Some College
|
102 (27.5)
|
82 (36.0)
|
10 (33.3)
|
0.06
|
Bachelor's or greater
|
87 (23.5)
|
70 (30.7)
|
10 (33.3)
|
0.06
|
Not reported
|
49 (13.2)
|
18 (7.9)
|
3 (10.0)
|
0.12
|
Pregnancy Induced Hypertension
|
31 (8.4)
|
18 (7.9)
|
1 (3.3)
|
0.36
|
Infant Characteristics
|
Small for gestational age
|
49 (13.2)
|
28 (12.3)
|
3 (10.0)
|
0.55
|
Male Sex
|
191 (51.5)
|
114 (50.0)
|
15 (50.0)
|
0.71
|
Gestational Age
|
25.5 (1.1)
|
25.7 (1.1)
|
25.9 (1.0)
|
<0.0001
|
Birth Weight z-score
|
-0.0 (0.9)
|
-0.1 (0.9)
|
-0.1 (1.0)
|
0.33
|
Birth Length z-score
|
-0.2 (0.9)
|
-0.6 (0.9)
|
-1.5 (1.6)
|
<0.0001
|
Birth Head Circumference z-score
|
-0.3 (0.8)
|
-0.2 (0.9)
|
-0.1 (2.6)
|
0.68
|
Time to Regain Birth Weight
|
9 (6-12)
|
8 (5-12)
|
8 (7-11)
|
0.37
|
Discharge Weight z-score
|
-1.0 (0.8)
|
-0.7 (0.8)
|
-0.4 (0.9)
|
<0.0001
|
Discharge Length z-score
|
-2.1 (1.3)
|
-1.0 (1.3)
|
0.3 (1.3)
|
<0.0001
|
Discharge Head Circumference z-score
|
-0.9 (1.2)
|
-0.6 (1.0)
|
-0.2 (0.9)
|
<0.0001
|
Severe NEC
|
16 (4.3)
|
8 (3.5)
|
0 (0.0)
|
0.35
|
Severe ICH
|
41 (11.1)
|
24 (10.5)
|
4 (13.3)
|
0.46
|
Severe BPD
|
223 (60.1)
|
145 (63.6)
|
22 (73.3)
|
0.04
|
Severe Sepsis
|
23 (6.2)
|
9 (3.9)
|
1 (3.3)
|
0.27
|
>14 days of dexamethasone
|
25 (6.7)
|
18 (7.9)
|
1 (3.3)
|
0.46
|
Length of stay (days)
|
103 (32)
|
102 (30)
|
99 (20)
|
0.690
|
Weight Growth Velocity (g/day)
|
21.0 (4.3)
|
22.9 (4.5)
|
26.0 (4.0)
|
<0.0001
|
Length Growth Velocity (cm/week)
|
0.91 (0.2)
|
1.1 (0.1)
|
1.5 (0.3)
|
<0.0001
|
BMI z-score at two years did not differ between those with weight or length accelerated, normal growth, or growth failure during their initial hospitalization. Growth velocity in the weight failure group was 19.6 (3.5) g/d compared to 24.0 (4.2) and 27.0 (4.1) in normal and accelerated growth cohorts, respectively (p<0.001) (Supplementary Table 1). Similarly, increase in length was slower in the length growth failure group compared to normal and accelerated growth cohorts: 0.91 (0.2) cm/week, 1.1 (0.1), and 1.5 (0.2) in growth failure, normal, and accelerated growth cohorts, respectively (p<0.001) (Table 1).
After adjusting for gestational age, maternal education, >14 days of dexamethasone, erythropoietin use, length z-score at birth, pregnancy induced hypertension (PIH), severe ICH, and feeding status at discharge, accelerated linear growth was associated with increased BSID-III cognitive score (+3.2 [0.02, 6.4], p=0.048), but not motor (+4.7 [-0.3, 9.8]) or language scores (+2.1 [-2.8, 7.0]), Figure 1. Weight and head circumference z-score change from birth to discharge were not associated with BSID-III cognitive, motor, or language scores.
When examining behavioral characteristics at two years, infants with weight and head circumference growth failure had significantly greater adjusted total M-CHAT-R score compared to those with normal weight growth (+0.43 [0.01,0.84], p=0.044 and +0.39 [0.04, 0.73], p=0.029). Infants with accelerated linear growth had a significantly lower adjusted total M-CHAT-R score compared to those with normal linear growth (-0.74 [-1.15, -0.34], p<0.01). There were no significant differences in CBCL scores in weight, length, or head circumference growth cohorts.
Growth from Discharge to Two Years
Cohort characteristics are described for weight in Table 2 and length in Supplementary Table 2. Mothers of infants with accelerated weight and linear growth after discharge were more likely to have a high school education or less (Table 2 and Supplementary Table 2). Infants with weight growth failure after discharge were more likely to have had severe ICH and severe BPD (Table 2). Those with accelerated linear growth after discharge were likely to be lower gestational age at birth and small for gestational age (Supplmentary Table 2).
Table 2. Cohort comparisons during the timeframe of neonatal intensive care unit discharge to two year infant follow-up clinic. Growth failure and accelerated growth were categorized as having weight growth failure or accelerated weight growth from discharge to two year follow-up. Categorical variables are represented by n (%). Continuous variables are represented with mean (SD). P-values were calculated with Chi-squared tests for categorical and ANOVA for continuous variables. Severe ICH was defined as grade III or IV either unilateral or bilateral, according to Papile staging. BPD was defined as requiring nasal canula or higher levels of respiratory support at 36 weeks postmenstrual age.
|
Weight Growth Failure, n (%)
|
Normal Weight Growth, n (%)
|
Accelerated Weight Growth n (%)
|
p-value
|
Included Infants
|
132
|
306
|
191
|
|
Gestational Age, weeks
|
25.5 (1.1)
|
25.6 (1.1)
|
25.6 (1.1)
|
0.99
|
Birth weight z-score
|
-0.2 (1.0)
|
-0.1 (0.8)
|
-0.0 (0.8)
|
0.047
|
Birth length z-score
|
-0.6 (1.2)
|
-0.4 (1.0)
|
-0.3 (1.0)
|
0.06
|
Birth head circumference z-score
|
-0.2 (1.3)
|
-0.3 (1.0)
|
-0.3 (0.8)
|
0.50
|
Maternal education
|
|
|
|
|
High School or less
|
31 (23.5)
|
87 (28.4)
|
80 (41.9)
|
0.0009
|
Some College
|
48 (36.4)
|
101 (33.0)
|
45 (23.6)
|
0.01
|
Bachelor's or greater
|
37 (28.0)
|
82 (26.8)
|
48 (25.1)
|
0.57
|
Not reported
|
16 (12.1)
|
36 (11.8)
|
18 (9.4)
|
0.44
|
SGA
|
24 (18.2)
|
38 (12.4)
|
18 (9.4)
|
0.04
|
PIH
|
11 (8.3)
|
18 (5.9)
|
21 (11.0)
|
0.33
|
GDM
|
11 (8.3)
|
12 (3.9)
|
10 (5.2)
|
0.36
|
Maternal obesity
|
8 (6.1)
|
35 (11.4)
|
20 (10.5)
|
0.22
|
Days to regain birth weight
|
8 (5-11)
|
9 (6-12)
|
9 (7-13)
|
0.01
|
Severe ICH
|
26 (19.7)
|
30 (9.8)
|
13 (6.8)
|
0.0008
|
Severe BPD
|
101 (76.5)
|
187 (61.1)
|
102 (53.4)
|
<0.0001
|
After adjusting for gestational age, maternal education, >14 days of dexamethasone, erythropoietin use, length z-score at birth, PIH, severe ICH, and feeding status at discharge, weight growth failure at follow-up was associated with decreased motor (-3.1 [-5.9, -0.2], p=0.035) scores, but not language (-2.0 [-5.0, 1.0] or cognitive scores (-1.1 [-4.0, 1.6]), Figure 2. There were no differences in BSID-III cognitive, motor, and language scores with changes in length or head circumference z-score.
When adjusting for gestational age, maternal education, >14 days of dexamethasone, erythropoietin use, length z-score at birth, PIH, severe BPD, feeding status at discharge, and severe ICH, infants with accelerated weight growth at two years had increased odds of total behavioral problems compared to those with normal growth and growth failure (OR 1.88 [1.03,3.45], p=0.041, Figure 3). Behavioral outcomes on the CBCL did not differ between linear or head circumference growth cohorts. There were no significant differences in M-CHAT-R scores.