Auditory brainstem response in full-term neonates born to mothers with iron deficiency anemia: relation to disease severity

Anemia, Iron Supplementation, and the Brain

The developing brain is particularly vulnerable to extrinsic environmental events such as anemia and iron deficiency during periods of rapid development. Studies of infants with postnatal iron deficiency and iron deficiency anemia clearly demonstrated negative effects on short-term and long-term brain development and function. Randomized interventional trials studied erythropoiesis-stimulating agents and hemoglobin-based red blood cell transfusion thresholds to determine how they affect preterm infant neurodevelopment. Studies of red blood cell transfusion components are limited in preterm neonates. A biomarker strategy measuring brain iron status and health in the preanemic period is desirable to evaluate treatment options and brain response.

Maternal gestational iron status and infant haematological and neurodevelopmental outcomes

Prevention of iron deficiency (ID), the most common micronutrient deficiency in infants and children, begins prenatally by ensuring adequate fetal loading. Adequate intrauterine iron status is crucial for normal fetal brain development, postnatal brain performance and prevention of early postnatal iron deficiency, particularly in infants fed exclusively human milk. Adequate fetal loading may be achieved in some cases through adequate maternal iron levels prior to pregnancy and oral iron supplementation during pregnancy. However, because so many women are iron-deficient leading up to pregnancy, coupled with the negative iron balance induced by pregnancy, a large number of women remain iron-deficient during pregnancy. More consistent iron-specific early screening and more effective iron delivery approaches are needed to solve this global problem.

Maternal, Perinatal, and Postnatal Predisposing Factors of Hearing Loss in Full-Term Children: A Matched Case-Control Study

INTRODUCTION

Studies on risk factors for childhood hearing loss (HL) are usually based on questionnaires or small sample sizes. We conducted a nationwide population-based case-control study to comprehensively analyze the maternal, perinatal, and postnatal risk factors for HL in full-term children.

METHODS

We retrieved data from three nationwide databases related to maternal characteristics, perinatal comorbidities, and postnatal characteristics and adverse events. We used 1:5 propensity score matching to include 12,873 full-term children with HL and 64,365 age-, sex-, and enrolled year-matched controls. Conditional logistic regression was used to evaluate the risk factors for HL.

RESULTS

Among the various maternal factors, maternal HL (adjusted odds ratio [aOR]: 8.09, 95% confidence interval [95% CI]: 7.16-9.16) and type 1 diabetes (aOR: 3.79, 95% CI: 1.98-7.24) had the highest odds of childhood hearing impairment. The major perinatal risk factors for childhood hearing impairment included ear malformations (aOR: 58.78, 95% CI: 37.5-92.0) and chromosomal anomalies (aOR: 6.70, 95% CI: 5.25-8.55), and the major postnatal risk factors included meningitis (aOR: 2.08, 95% CI: 1.18-3.67) and seizure (aOR: 3.71, 95% CI: 2.88-4.77). Other factors included acute otitis media, postnatal ototoxic drug use, and congenital infections.

CONCLUSIONS

Many risk factors for childhood HL identified in our study are preventable, such as congenital infection, meningitis, ototoxic drug use, and some maternal comorbidities. Accordingly, more effort is required to prevent and control the severity of maternal comorbidities during pregnancy, initiate genetic diagnostic evaluation for high-risk children, and aggressive screening for neonatal infections.

Maternal Iron Status in Pregnancy and Child Health Outcomes after Birth: A Systematic Review and Meta-Analysis

In pregnancy, iron deficiency and iron overload increase the risk for adverse pregnancy outcomes, but the effects of maternal iron status on long-term child health are poorly understood. The aim of the study was to systematically review and analyze the literature on maternal iron status in pregnancy and long-term outcomes in the offspring after birth. We report a systematic review on maternal iron status during pregnancy in relation to child health outcomes after birth, from database inception until 21 January 2021, with methodological quality rating (Newcastle-Ottawa tool) and random-effect meta-analysis. (PROSPERO, CRD42020162202). The search identified 8139 studies, of which 44 were included, describing 12,7849 mother–child pairs. Heterogeneity amongst the studies was strong. Methodological quality was predominantly moderate to high. Iron status was measured usually late in pregnancy. The majority of studies compared categories based on maternal ferritin, however, definitions of iron deficiency differed across studies. The follow-up period was predominantly limited to infancy. Fifteen studies reported outcomes on child iron status or hemoglobin, 20 on neurodevelopmental outcomes, and the remainder on a variety of other outcomes. In half of the studies, low maternal iron status or iron deficiency was associated with adverse outcomes in children. Meta-analyses showed an association of maternal ferritin with child soluble transferrin receptor concentrations, though child ferritin, transferrin saturation, or hemoglobin values showed no consistent association. Studies on maternal iron status above normal, or iron excess, suggest deleterious effects on infant growth, cognition, and childhood Type 1 diabetes. Maternal iron status in pregnancy was not consistently associated with child iron status after birth. The very heterogeneous set of studies suggests detrimental effects of iron deficiency, and possibly also of overload, on other outcomes including child neurodevelopment. Studies are needed to determine clinically meaningful definitions of iron deficiency and overload in pregnancy.

Anaemia in chronic kidney disease pregnancy

AIM

To review the incidence and management of anaemia and outcomes in pregnancies in a cohort of Australian women with chronic kidney disease.

METHODS

A retrospective audit of 63 pregnancies in 52 women with chronic kidney disease.

RESULTS

Sixty-eight percent of chronic kidney disease pregnancies were complicated by haemoglobin less than 100 g/L. Iron stores were measured in only 62% of all pregnancies. Serum ferritin was less than 100 ng/ml in 95% of those tested. Erythropoietin-stimulating agents were used in 24 pregnancies (38%). Intravenous iron was used in only nine non-dialysis pregnancies.

CONCLUSION

Greater awareness of the importance of regular measurement of iron stores and appropriate levels for repletion in chronic kidney disease pregnancies amongst health professionals involved in obstetric care may result in earlier detection and treatment of iron deficiency, and potentially improve maternal and fetal outcomes.

Behavioral consequences at 5 y of neonatal iron deficiency in a low-risk maternal-infant cohort

BACKGROUND

Iron is critical to the developing brain, but fetal iron accretion is compromised by several maternal and pregnancy-related factors. Little consideration has been given to the long-term neurologic consequences of neonatal iron deficiency, especially in generally healthy, low-risk populations.

OBJECTIVE

We aimed to investigate the association between neonatal iron deficiency and neurologic development at 2 and 5 y of age.

DESIGN

We measured umbilical cord serum ferritin concentrations in the prospective maternal-infant Cork BASELINE (Babies after SCOPE: Evaluating the Longitudinal Impact Using Neurological and Nutritional Endpoints) Birth Cohort. Lifestyle and clinical data were collected from 15 weeks of gestation to 5 y of age. Standardized neurologic assessments were performed at 2 y [Bayley Scales of Infant Development/Child Behavior Checklist (CBCL)] and 5 y (Kaufman Brief Intelligence Test/CBCL).

RESULTS

Among 697 maternal-infant pairs, median (IQR) cord ferritin concentrations were 200.9 (139.0, 265.8) µg/L; 8% had neonatal iron deficiency (ferritin <76 µg/L). Using fully adjusted models, there was no association between neonatal iron deficiency and cognitive or behavioral outcomes at 2 or 5 y. We conducted an a priori sensitivity analysis in 306 high-risk children, selected using known risk factors for neonatal iron deficiency (smoking/obesity/cesarean section delivery/small-for-gestational age birth). In this high-risk subgroup, children with iron deficiency at birth (12%) had similar cognitive outcomes, but the behavioral assessments showed higher internalizing [9.0 (5.3, 12.0) compared with 5.0 (3.0, 10.0), P = 0.006; adjusted estimate (95% CI): 2.8 (0.5, 5.1), P = 0.015] and total [24.5 (15.3, 40.8) compared with 16.0 (10.0, 30.0), P = 0.009; adjusted estimate (95% CI): 6.6 (0.1, 13.1), P = 0.047] problem behavior scores at 5 y compared with those born iron sufficient.

CONCLUSIONS

We have demonstrated lasting behavioral consequences of neonatal iron deficiency in high-risk children from our generally healthy, low-risk maternal-infant cohort. Although larger investigations are warranted, this study provides strong association data to suggest that interventions and strategies targeting the fetal and neonatal period should be prioritized for the prevention of iron deficiency and associated neurologic consequences.

Adverse effects of iron deficiency anemia on pregnancy outcome and offspring development and intervention of three iron supplements

Iron deficiency anemia (IDA) is a common micronutrient deficiency among pregnant women with severe consequences including impaired immuno-inflammatory system, premature birth, fetal death etc. The present study aimed to investigate the effects of three iron supplements on IDA female rats and their offspring. The IDA female rat model was established with low iron diet and the rats were then mated. After pregnancy, rats were fed diets containing different iron supplements (iron polysaccharide complex, iron protein succinylate and ferrous sulfate) until their offspring were 42 days old. Pregnancy outcomes, haematological, iron metabolism, physical and neurological development indexes were determined. The results showed that all three iron supplements improved the levels of hematological parameters of both mother and offspring rats. After iron supplementation, serum iron, transferrin saturation and serum ferritin levels were increased compared with the IDA group. The level of ferritin light chain in the liver and spleen of both mother and offspring rats in iron supplemented groups was significantly higher than that of the IDA group. The average number of born alive per litter in the iron treatment groups was significantly higher than that in the IDA group. Iron supplements also improved the physical growth and neurobehavioral development of offspring rats. It was also found that iron supplementation improved the expression of ferritin light chain and the synaptic growth associated proteins in the brain and hippocampus. No significant difference was found in the efficacy of three iron supplements. These results suggest that pregnant and postpartum IDA affects pregnancy outcomes, offspring physical development and causes neural impairment. Sufficient iron supplementation can significantly improve IDA and its adverse effects on both mother and offspring.

The Role of Iron in Brain Development: A Systematic Review

One-third of children falter in cognitive development by pre-school age. Iron plays an important role in many neurodevelopmental processes, and animal studies suggest that iron sufficiency in pregnancy and infancy is particularly important for neurodevelopment. However, it is not clear whether iron deficiency directly impacts developmental outcomes, and, if so, whether impact differs by timing of exposure or developmental domain. We searched four databases for studies on iron deficiency or iron supplementation in pregnancy, or at 0-6 months, 6-24 months, or 2-4 years of age. All studies included neurodevelopmental assessments in infants or children up to 4 years old. We then qualitatively synthesized the literature. There was no clear relationship between iron status and developmental outcomes across any of the time windows or domains included. We identified a large quantity of low-quality studies, significant heterogeneity in study design and a lack of research focused on pregnancy and early infancy. In summary, despite good mechanistic evidence for the role of iron in brain development, evidence for the impact of iron deficiency or iron supplementation on early development is inconsistent. Further high-quality research is needed, particularly within pregnancy and early infancy, which has previously been neglected.

Impairment of the Developing Human Brain in Iron Deficiency: Correlations to Findings in Experimental Animals and Prospects for Early Intervention Therapy

Due to the necessity of iron for a variety of cellular functions, the developing mammalian organism is vulnerable to iron deficiency, hence causing structural abnormalities and physiological malfunctioning in organs, which are particularly dependent on adequate iron stores, such as the brain. In early embryonic life, iron is already needed for proper development of the brain with the proliferation, migration, and differentiation of neuro-progenitor cells. This is underpinned by the widespread expression of transferrin receptors in the developing brain, which, in later life, is restricted to cells of the blood–brain and blood–cerebrospinal fluid barriers and neuronal cells, hence ensuring a sustained iron supply to the brain, even in the fully developed brain. In embryonic human life, iron deficiency is thought to result in a lower brain weight, with the impaired formation of myelin. Studies of fully developed infants that have experienced iron deficiency during development reveal the chronic and irreversible impairment of cognitive, memory, and motor skills, indicating widespread effects on the human brain. This review highlights the major findings of recent decades on the effects of gestational and lactational iron deficiency on the developing human brain. The findings are correlated to findings of experimental animals ranging from rodents to domestic pigs and non-human primates. The results point towards significant effects of iron deficiency on the developing brain. Evidence would be stronger with more studies addressing the human brain in real-time and the development of blood biomarkers of cerebral disturbance in iron deficiency. Cerebral iron deficiency is expected to be curable with iron substitution therapy, as the brain, privileged by the cerebral vascular transferrin receptor expression, is expected to facilitate iron extraction from the circulation and enable transport further into the brain.