Postnatal weight gain and retinopathy of prematurity in preterm infants: a population-based retrospective cohort study

Figures & data

Figure 1. Flow diagram of the study.

Table 1. Univariate analysis of risk factors for the development of ROP.

	Infants (n = 675)			Infants with ROP (n = 278)
	ROP (−) (n = 397)	ROP (+) (n = 278)	p	No treated (n = 241)	Treated (n = 37)	p
Maternal factors
Maternal age, (years)	29.8 ± 5.90	30 ± 5.47	^a0.569	30 ± 5.5	29 ± 5.3	^b0.418
Consanguineous marriage, n (%)	43 (11)	39 (14)	^a0.172	34 (14.5)	5 (14)	^a0.927
Antenatal steroid, n (%)	211 (%56)	163 (64)	^a0.031	143 (65)	20 (62.5)	^b0.963
IUGR, n (%)	78 (21)	78 (29)	^a0.012	67 (29)	11 (32.4)	^b0.855
Cesarean delivery, n (%)	337 (85)	229 (84)	^a0.668	204 (86)	25 (69)	^b0.963
In vitro fertilization, n (%)	61 (15)	40 (14)	0.741	37 (15.4)	3 (8)	^b0.359
Premature rupture of membranes, n (%)	84 (22)	58 (22)	^a0.998	46 (20)	12 (33)	^b0.107
Chorioamnionitis, n (%)	10 (2.6)	9 (3.4)	^b0.758	7 (3)	2 (5.7)	^e0.336
Multiple gestation	92 (23)	69 (25)	^a0.621	58 (24)	11 (30)	^b0.590
Preeclampsia, n (%)	141 (37)	98 (37)	^a0.618	87 (37.5)	11 (31.4)	^a0.659
Diabetes mellitus, n (%)	23 (6)	18 (7)	^b0.846	16 (7)	2 (%5.7)	^e1.000
Smoking, n (%)	24 (6.5)	21 (8)	^a0.465	17 (7.5)	4 (12)	^e0.494
Neonatal factors
Gestational age (week)	30.08 ± 1.60	28.48 ± 1.95	^c0.001	28.7 ± 1.8	27.2 ± 2.3	^c0.001
Birth weight (g)	1301 ± 349	973 ± 288	^c0.001	1000 ± 288	781 ± 198	^c0.001
Male, n (%)	194 (% 48.9)	138 (% 49.6)	0.843	119 (49)	19 (51)	^b0.963
SGA, n (%)	81 (20)	100 (36)	^a0.001	81 (33.6)	19 (51.4)	^b0.056
Cord pH	7.28 ± 0.11	7.29 ± 0.11	^c0.224	7.30 ± 0.1	7.24 ± 0.1	^c0.061
Cardiopulmonary resuscitation, n (%)	70 (18)	136 (51)	^a0.001	107 (46)	29 (81)	^b0.001
Apgar score 1.min	6 ± 2	5 ± 2	^d0.001	5.4 ± 2.1	4 ± 1.9	^d0.001
Apgar score 5.min	8 ± 1 (9)	7 ± 1 (8)	^d0.001	7.6 ± 1.5	6.4 ± 1.7	^d0.001
Respiratory distress syndrome, n (%)	137 (35)	186 (69)	^a0.001	153 (66)	32 (91)	^b0.004
Bronchopulmonary dysplasia, n (%)	49 (14)	121 (48)	^a0.001	91 (42)	30 (91)	^e0.001
Intraventricular hemorrhage (Stage 3–4), n (%)	11 (3)	31 (12)	^b0.001	23 (10.5)	8 (23.5)	^e0.046
Patent ductus arteriosus, n (%)	79 (%22)	109 (%43)	^a0.001	90 (41)	19 (58)	^b0.102
Necrotizing enterocolitis (Stage-2–3), n (%)	2 (0.6)	12 (5)	^b0.001	6 (3)	6 (19)	^e0.002
Periventricular leukomalacia, n (%)	8 (2.3)	8 (3.3)	^b0.627	6 (3)	2 (6.5)	^e0.274
Sepsis, n (%)	224 (61)	222 (84)	^a0.001	188 (82.5)	34 (97)	^b0.048
Hyperbilirubinemia, n (%)	362 (95)	255 (97)	^b0.163	222 (97.4)	33 (97)	^e1.000
Apnea, n (%)	100 (28)	138 (55)	^a0.001	117 (54)	21 (66)	^b0.280
Postnatal steroid therapy, n (%)	36 (10)	87 (35)	^a0.001	64 (30)	23 (74)	^b0.001
Caffeine or theophylline, n (%)	86 (25)	73 (29)	^a0.206	65 (30)	8 (26)	^b0.792
Thyroxine (pmol/L)	14.1 ± 3.5	12.5 ± 3.2	^d0.001	12.6 ± 3.2	11.5 ± 3.1	^c0.057
Thyroid Stimulating Hormone (mUI/L)	3.89 ± 8.9	3.39 ± 10.6	^d0.001	3.66 ± 11.4	1,68 ± 2.2	^d0.001
Thrombocytopenia (< 100,000/mm^3), n (%)	115 (34)	124 (52)	^a0.001	102 (49)	22 (71)	^b0.035
Hyperglycemia, n (%)	15 (4.3)	30 (12)	^b0.001	23 (11)	7 (21)	^e0.093
Mechanical ventilation duration (days)	2.26 ± 5.92	10.59 ± 22.19	^a0.001	7.95 ± 16.4	28 ± 40	^d0.001
Noninvasive ventilation duration (days)	2.5 ± 4.6	7.6 ± 9.6	^c0.001	7 ± 8.8	12 ± 13	^d0.003
Oxygen therapy (days)	4.3 ± 9.5	10.1 ± 13.4	^c0.001	8.9 ± 12	18.2 ± 18	^d0.009
Surfactant administration, n (%)	137 (35)	186 (69)	^a0.001	153 (65.7)	33 (92)	^b0.003
Parenteral nutrition duration (days)	12.48 ± 9.2	20.17 ± 20	^d0.001	12.5 ± 9	20 ± 20	^d0.032
Blood transfusion, (number)	1.51 ± 2.11	4.22 ± 4.04	^a0.001	3.7 ± 3.6	7.6 ± 4.9	^d0.001

^a Pearson’s chi-square test.

^b Yates continuity correction test.

^c Student’s t-test.

^d Mann–Whitney U test.

^e Fisher’s exact test.

The values are presented as mean ± standard deviation. IUGR, intrauterine growth restriction; ROP, retinopathy of prematurity; SGA, small for gestational age.

Table 2. Comparison of the daily weight gain in non-ROP and ROP groups according to weeks.

	ROP (−) (n = 397)	ROP (+) (n = 278)	p
Weight gain at 1th week	−9.6 ± 8.11	−8.7 ± 9.1	^d0.517
Weight gain at 2th week	13.1 ± 8.1	13.2 ± 9.8	^d0.687
Weight gain at 3th week	15.4 ± 6.8	13.9 ± 8.2	^d0.034
Weight gain at 4th week	16.4 ± 6.8	15.6 ± 8.7	^d0.861
Weight gain at 5th week	15.7 ± 7.1	14.6 ± 8.8	^d0.180
Weight gain at 6th week	14.5 ± 7.5	16 ± 7.7	^d0.049
Weight gain at 7th week	13.8 ± 7.3	15.5 ± 7.8	^d0.017
Weight gain at 8th week	12.1 ± 8.2	14.1 ± 8.4	^d0.098

^dMann–Whitney U test. ROP, retinopathy of prematurity.

Table 3. Independent risk factors for retinopathy of prematurity.

Variables	Odds ratio	95 % CI	p
Birth weight (< 750 g)	8.67	3.99–18.82	0.001**
Birth weight (750–999g)	4.91	2.78–8.66	0.001**
Birth weight (1000–1249g)	2.58	1.51–4.43	0.001**
Blood transfusion	2.39	1.34–4.24	0.003**
Necrotizing enterocolitis	4.79	1.05–26.85	0.045*
Bronchopulmonary dysplasia	2.03	1.22–3.36	0.006**
Antenatal steroid therapy	1.60	1.05–2.43	0.028*
Surfactant administration	2.06	1.32–3.2	0.001**

CI, confidence interval. *p < 0.05; **p < 0.01.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author, [initials]. The data are not publicly available due to [restrictions e.g. their containing information that could compromise the privacy of research participants].