Effects of iron supplements and perinatal factors on fetal hemoglobin disappearance in LBW infants

Growth and micronutrient status parameters of Nigerian preterm infants consuming preterm formula or breastmilk

BACKGROUND

Moderate-to-late preterm infants (32-34 weeks GA) have increased risk of neonatal morbidities compared to term infants, however dedicated nutritional guidelines are lacking.

METHODS

Moderate-to-late preterm infants received a preterm formula (n = 17) or breastmilk (n = 24) from age 2-10 weeks in a non-randomized, open-label observational study. Anthropometric measurements were assessed bi-weekly. Blood concentrations of hemoglobin, ferritin, serum retinol, and 25-hydroxy-vitamin D (25OHD) were analyzed at age 2 and 10 weeks.

RESULT

Average growth per day was 14.7 g/kg BW/day in formula-fed and 12.8 g/kg BW/day in breastmilk-fed infants but not different from each other. Length and head circumference in both groups were in line with the median reference values of the Fenton growth chart. At 10 weeks of age, hemoglobin tended to be higher in the formula-fed group (10.2 g/dL vs. 9.6 g/dL, p = 0.053). 25OHD increased in formula- and breastmilk-fed infants from 73.8 to 180.9 nmol/L and from 70.7 to 97.6 nmol/L, respectively. Serum retinol only increased in the formula-fed group (0.63 to 1.02 µmol/L, p < 0.001).

CONCLUSION

Breastfeeding resulted in adequate growth in moderate-late preterm infants but was limiting in some micronutrients. The preterm formula provided adequate micronutrients, but weight gain velocity was higher than the Fenton reference value.

IMPACT STATEMENT

Unfortified breastmilk resulted in adequate growth in weight, length and head circumference in Nigerian moderate to late preterm infants during an study period of 8 weeks, but status of vitamin D, vitamin A and iron needs to be monitored. The high-energy formula, developed for very preterm infants, resulted in higher growth in body weight in moderate to late preterm infants than the median of the Fenton preterm growth chart. This study supports the necessity of dedicated nutritional guidelines, and regular monitoring of growth and nutritional status of moderate to late preterm infants.

Simplified bedside assessment of pulmonary gas exchange in very preterm infants at 36 weeks' postmenstrual age

INTRODUCTION

We aimed to develop and validate a prediction table for a simplified measure of rightward shift of the fetal oxyhaemoglobin saturation (SpO₂) versus inspired oxygen pressure (P _IO₂) curve as an objective marker of lung disease severity in very preterm infants, independent of unit altitude or oxygen prescribing policies.

METHODS

Very preterm infants (n=219) had an oxygen reduction test at median (IQR) test age of 35⁴ (34⁵-36⁰) weeks' postmenstrual age (PMA). Shift was derived from at least three paired SpO₂ versus P _IO₂ measurements using a computer algorithm, using the fetal oxyhaemoglobin dissociation curve as the reference. Linear regression of resultant shift values enabled construction of a table to predict shift using a single paired SpO₂ versus P _IO₂ measurement, validated subsequently in a separate infant cohort using Bland-Altman analysis. Receiver operating curve analysis provided threshold values equating to a clinical diagnosis of mild bronchopulmonary dysplasia (BPD) or moderate to severe BPD.

RESULTS

The median (IQR) age of 63 infants in the validation cohort was 36⁰ (35⁶-36²) weeks' PMA. Mean difference (95% CI) between predicted and measured shift was 2.1 (-0.8% to 4.9%) with wide limits of agreement (-20.7% to 24.8%). Predicted shift >10.1 kPa identified mild BPD with 71% sensitivity and 88% specificity while values>13.0 kPa identified moderate to severe BPD with 81% sensitivity and 100% specificity.

DISCUSSION

Shift predicted from a single paired SpO₂ versus P _IO₂ measurement using our validated table enables objective bedside screening of lung disease severity in very preterm infant cohorts at 36 weeks' PMA.

Pulmonary Gas Exchange Improves over the First Year in Preterm Infants with and without Bronchopulmonary Dysplasia

BACKGROUND

Right shift of the peripheral oxyhaemoglobin saturation (SpO2) versus inspired oxygen pressure (PIO2) curve is a sensitive marker of pulmonary gas exchange.

OBJECTIVES

The aim of this study was to assess the impact of prematurity and bronchopulmonary dysplasia (BPD) on gas exchange and right-to-left shunt in the neonatal period, and its evolution over the first year of life.

METHOD

We assessed shift and shunt in extremely preterm (EP) and very preterm (VP) infants at 36 and 44 weeks' postmenstrual age (PMA), and at 1-year corrected postnatal age (cPNA). PIO2 was decreased stepwise to achieve SpO2 between 85 and 98%. Shift and shunt were calculated from paired SpO2/PIO2 measurements using customized software. Results were examined cross-sectionally at each time point, and longitudinally using generalized linear regression. Term infants were assessed at 44 wk PMA as a comparative reference.

RESULTS

Longitudinal modelling showed continuous decline in shift in EP and VP infants during the first year of life. There was no difference in shift compared to term infants at 44 wk PMA (p = 0.094). EP infants with BPD had higher shift than infants without BPD at 36 wk PMA (p < 0.001) and 44 wk PMA (p = 0.005) but not at 1-year cPNA.

CONCLUSIONS

In the absence of lung disease, prematurity per se did not result in reduced gas exchange at 1-year cPNA. We report ongoing, significant improvements in pulmonary gas exchange in all preterm infants during the first year of life, despite evidence of early deficits in gas exchange in EP infants with BPD.

Physiology and Predictors of Impaired Gas Exchange in Infants with Bronchopulmonary Dysplasia

Rationale: A sensitive outcome measure for infants with bronchopulmonary dysplasia would facilitate clinical benchmarking and enhance epidemiologic understanding, evaluation of clinical interventions, and outcome prediction.Objectives: Noninvasive assessment of pulmonary gas exchange in preterm infants with and without bronchopulmonary dysplasia to grade disease severity and to identify determinants of impaired gas exchange.Methods: This is a prospective observational study in very preterm infants. Inspired oxygen partial pressure (Pi_O2) was decreased stepwise to achieve oxygen saturation as measured by pulse oximetry (Sp_O2) that decreased from 95% to 86%. Right shift, V⋅a/Q⋅, and right-left shunt were derived from the resulting Sp_O2 versus Pi_O2 curve and compared with current disease severity classification. Potential determinants of shift, V⋅a/Q⋅, and shunt were identified using principal components analysis and multiple linear regression.Measurements and Main Results: A total of 219 infants with median (interquartile range) gestation of 28 weeks and 0 days (26 weeks and 0 days to 29 weeks and 0 days) had a valid study at 35 weeks and 4 days (34 weeks and 1 day to 39 weeks and 3 days) of postmenstrual age. Shift increased and V⋅a/Q⋅ decreased as severity of bronchopulmonary dysplasia increased. Infants with moderate-severe disease also had increased shunt. Extent of impaired gas exchange overlapped between severity groups. Infants requiring mechanical support but no supplemental oxygen at 36 weeks' postmenstrual age had similar values of shift, V⋅a/Q⋅, and shunt to preterm infants without bronchopulmonary dysplasia. Lower gestation and increased duration of invasive ventilation independently predicted increased shift, decreased V⋅a/Q⋅, and increased shunt. Shift was the most sensitive and specific index of the severity of bronchopulmonary dysplasia.Conclusions: Most infants with bronchopulmonary dysplasia have impaired oxygenation quantified by a simple, sensitive bedside test. Shift of the Sp_O2/Pi_O2 curve may be useful for prediction and measurement of preterm infant respiratory outcomes.

Reference Ranges of Reticulocyte Haemoglobin Content in Preterm and Term Infants: A Retrospective Analysis

BACKGROUND

Despite iron supplementation, some preterm infants develop iron deficiency (ID). The optimal iron status parameter for early detection of ID has yet to be determined.

OBJECTIVE

To establish reference ranges for reticulocyte haemoglobin content (Ret-He) in preterm and term infants and to identify confounding factors.

METHODS

Retrospective analyses of Ret-He and complete blood count in infants with a clinically indicated blood sample obtained within 24 h after birth.

RESULTS

Mean (SD) Ret-He was 30.7 (3.0) pg in very preterm infants with a gestational age (GA) of <30 weeks (n = 55), 31.2 (2.6) pg in moderately preterm infants (GA 30-36 weeks, n = 241) and 32.0 (3.2) pg in term infants (GA ≥37 weeks, n = 216). The 2.5th percentile of Ret-He across all GA groups was 25 pg, with a weak correlation between Ret-He and GA (r = 0.18). Moreover, only weak/no correlations were found between Ret-He and C-reactive protein (r = 0.18), interleukin 6 (IL-6) (r = 0.03) and umbilical artery pH (r = -0.07). There was a slight variation in Ret-He with mode of delivery [normal vaginal delivery: 32.3 (3.2) pg, secondary caesarean section (CS): 31.4 (3.0) pg, instrumental delivery: 31.3 (2.7) pg and elective CS: 31.2 (2.8) pg].

CONCLUSION

GA at birth has a negligible impact on Ret-He, and the lower limit of the normal reference range in newborns within 24 h after birth can be set to 25 pg. Moreover, Ret-He seems to be a robust parameter which is not influenced by perinatal factors within the first 24 h after birth.

Reticulocyte Haemoglobin Content Declines More Markedly in Preterm than in Term Infants in the First Days after Birth

BACKGROUND

Reticulocyte haemoglobin content, i.e., the reticulocyte equivalent (Ret-He), seems to be a promising parameter for the detection of iron deficiency (ID) in neonates because it can be obtained as part of a reticulocyte count, with no additional blood loss and at no extra cost. Due to the short life span of reticulocytes, Ret-He reflects current iron availability for erythropoiesis more accurately than other common erythrocyte indices.

OBJECTIVE

We aimed to evaluate postnatal changes in Ret-He within the first days after birth in term and preterm infants with the hypothesis that preterm infants experience a more pronounced postnatal reduction in Ret-He when compared to term infants.

METHODS

We conducted retrospective analyses of clinically indicated blood samples. Paired t test and mixed regression modelling were used.

RESULTS

In total, 805 blood samples obtained from 207 term and 295 preterm infants were analysed. Ret-He decreased by 1.5 pg per day (regression coefficient [95% CI] -1.5 [-1.8 to -1.2] pg, p < 0.0001). This drop was more significant in preterm infants (regression coefficient -2.2 [-2.6 to -1.8] pg, p < 0.0001) than in term infants (regression coefficient -0.8 [-1.3 to -0.2] pg, p < 0.01, pinteraction < 0.0001).

CONCLUSION

Ret-He declined within the first days after birth. The observed changes with postnatal age were more pronounced in preterm than in term infants. Further studies are needed to evaluate if these changes are due to developing ID or other causes.