The impact of maternal inflammation and maternal stress in the regulation of neurodevelopment and physiological function

The mechanisms governing fetal development follow a tightly regulated pattern of progression such that interference at any one particular stage is likely to have consequences for all other stages of development in the physiological system that has been affected thereafter. These disturbances can take the form of many different events but two of the most common and widely implicated in causing detrimental effects to the developing fetus are maternal immune activation (MIA) and maternal stress. MIA has been shown to cause an increase in circulating proinflammatory cytokines in both the maternal and fetal circulation. This increase in proinflammatory mediators in the fetus is thought to occur by fetal production rather than through exchange between the maternal-fetal interface. In the case of maternal stress it is increased levels of stress related hormones such as cortisol/corticosterone which is thought to elicit the detrimental effects on fetal development. In the case of both maternal infection and stress the timing and nature of the insult generally dictates the severity and type of effects seen in affected offspring. We investigated the effect of a proinflammatory environment on neural precursor cells of which exposure resulted in a significant decrease in the normal rate of proliferation of NPCs in culture but did not have any effect on cell survival. These effects were seen to be age dependent. Using a restraint stress model we investigated the effects of prenatal stress on the development of a number of different physiological systems in the same cohort of animals. PNS animals exhibited a number of aberrant changes in cardiovascular function with altered responses to stress and hypertension, modifications in respiratory responses to hypercapnic and hypoxic challenges and discrepancies in gastrointestinal innervation. Taken together these findings suggest that both maternal infection and maternal stress are detrimental to the normal development of the fetus.

Variations between post- and pre-harvest seasons in stunting, wasting, and Infant and Young Child Feeding (IYCF) practices among children 6-23 months of age in lowland and midland agro-ecological zones of rural Ethiopia

Introduction: Food availability and access are strongly affected by seasonality in Ethiopia. However, there are little data on seasonal variation in Infant and Young Child Feeding (IYCF) practices and malnutrition among 6-23 months old children in different agro-ecological zones of rural Ethiopia. Methods: Socio-demographic, anthropometry and IYCF indicators were assessed in post- and pre-harvest seasons among children aged 6–23 months of age randomly selected from rural villages of lowland and midland agro-ecological zones. Results: Child stunting and underweight increased from prevalence of 39.8% and 26.9% in post-harvest to 46.0% and 31.8% in pre-harvest seasons, respectively. The biggest increase in prevalence of stunting and underweight between post- and pre-harvest seasons was noted in the midland zone. Wasting decreased from 11.6% post-harvest to 8.5% pre-harvest, with the biggest decline recorded in the lowland zone. Minimum meal frequency, minimum acceptable diet and poor dietary diversity increased considerably in pre-harvest compared to post-harvest season in the lowland zone. Feeding practices and maternal age were predictors of wasting, while women’s dietary diversity and children age was predictor of child dietary diversity in both seasons. Conclusion: There is seasonal variation in malnutrition and IYCF practices among children 6-23 months of age with more pronounced effect in midland agro-ecological zone. A major contributing factor for child malnutrition may be poor feeding practices. Health information strategies focused on both IYCF practices and dietary diversity of mothers could be a sensible approach to reduce the burden of child malnutrition in rural Ethiopia.

The effect of gestational and lactational age on the human milk metabolome

Human milk is the ideal nutrition source for healthy infants during the first six months of life and a detailed characterisation of the composition of milk from mothers that deliver prematurely (<37 weeks gestation), and of how human milk changes during lactation, would benefit our understanding of the nutritional requirements of premature infants. Individual milk samples from mothers delivering prematurely and at term were collected. The human milk metabolome, established by (NMR) spectroscopy, was influenced by gestational and lactation age. Metabolite profiling identified that levels of valine, leucine, betaine, and creatinine were increased in colostrum from term mothers compared with mature milk, while those of glutamate, caprylate, and caprate were increased in mature term milk compared with colostrum. Levels of oligosaccharides, citrate, and creatinine were increased in pre-term colostrum, while those of caprylate, caprate, valine, leucine, glutamate, and pantothenate increased with time postpartum. There were differences between pre-term and full-term milk in the levels of carnitine, caprylate, caprate, pantothenate, urea, lactose, oligosaccharides, citrate, phosphocholine, choline, and formate. These findings suggest that the metabolome of pre-term milk changes within 5-7 weeks postpartum to resemble that of term milk, independent of time of gestation at pre-mature delivery.

Iron status in early life and associations with developmental outcomes

Infants and young children are at particular risk of iron deficiency and its associated consequences for growth and development. The main objectives of this thesis were to quantify iron intakes, status and determinants of status in two year olds; explore determinants of neonatal iron stores; investigate associations between iron status at birth and two years with neurodevelopmental outcomes at two years and explore the influence of growth on iron status in early childhood, using data from the Cork BASELINE (Babies after SCOPE: Evaluating Longitudinal Impact using Neurological and Nutritional Endpoints) Birth Cohort Study (n=2137). Participants were followed prospectively with interviewer-led questionnaires and clinical assessments at day 2 and at 2, 6, 12 and 24 months. At two years, there was a low prevalence of iron deficiency and iron deficiency anaemia in this cohort, representing the largest study of iron status in toddlers in Europe, to date. The increased consumption of iron-fortified products and compliance with recommendations to limit unmodified cows’ milk intakes in toddlers has contributed to the observed improvements in status. Low serum ferritin concentrations at birth, which reflect neonatal iron stores, were shown to track through to two years of age; delivery by Caesarean section, being born small-for-gestational age and maternal obesity and smoking in pregnancy were all associated with significantly lower neonatal iron stores. Despite a low prevalence of iron deficiency in this cohort, both a mean corpuscular volume <74fl and ferritin concentrations <20μg/l were associated with lower neurodevelopmental outcomes at two years. An inverse association between growth in the second year of life and iron status at two years was also observed. This thesis has presented data from one of the largest, extensively-characterised cohorts of young children, to date, to explore iron and its associations with growth and development.