Sex-specific differences in HPA axis activity in VLBW preterm newborns

OBJECTIVE

Sex-specific differences in hypothalamic-pituitary-adrenal axis activity might explain why male preterm infants are at higher risk of neonatal mortality and morbidity than their female counterparts. We examined whether male and female preterm infants differed in cortisol production and metabolism at 10 days post-partum.

DESIGN AND METHODS

This prospective study included 36 preterm born infants (18 boys) with a very low birth weight (VLBW) (<1.500 g). At 10 days postnatal age, urine was collected over a 4- to 6-h period. Glucocorticoid metabolites were measured using gas chromatography-mass spectrometry. Main outcome measures were: (1) cortisol excretion rate, (2) sum of all glucocorticoid metabolites, as an index of corticosteroid excretion rate, and (3) ratio of 11-OH/11-OXO metabolites, as an estimate of 11B-hydroxysteroid dehydrogenase (11B-HSD) activity. Differences between sexes, including interaction with Score of Neonatal Acute Physiology Perinatal Extension-II (SNAPPE II), sepsis and bronchopulmonary dysplasia (BPD), were assessed.

RESULTS

No differences between sexes were found for cortisol excretion rate, corticosteroid excretion rate or 11B-HSD activity. Interaction was observed between: sex and SNAPPE II score on 11B-HSD activity (P = 0.04) and sex and BPD on cortisol excretion rate (P = 0.04).

CONCLUSION

This study did not provide evidence for sex-specific differences in adrenocortical function in preterm VLBW infants on a group level. However, in an interaction model, sex differences became manifest under stressful circumstances. These patterns might provide clues for the male disadvantage in neonatal mortality and morbidity following preterm birth. However, due to the small sample size, the data should be seen as hypothesis generating.

Early Use of Antibiotics Is Associated with a Lower Incidence of Necrotizing Enterocolitis in Preterm, Very Low Birth Weight Infants: The NEOMUNE-NeoNutriNet Cohort Study

OBJECTIVE

To determine whether commencement of antibiotics within 3 postnatal days in preterm, very low birth weight (VLBW; ≤1500 g) infants is associated with the development of necrotizing enterocolitis (NEC).

STUDY DESIGN

Preplanned statistical analyses were done to study the association between early antibiotic treatment and later NEC development, using the NEOMUNE-NeoNutriNet cohort of VLBW infants from 13 neonatal intensive care units (NICUs) in 5 continents (n = 2831). NEC incidence was compared between infants who received early antibiotics and those who did not, with statistical adjustments for NICU, gestational age, birth weight, sex, delivery mode, antenatal steroid use, Apgar score, and type and initiation of enteral nutrition.

RESULTS

The incidence of NEC was 9.0% in the group of infants who did not receive early antibiotics (n = 269), compared with 3.9% in those who did receive early antibiotics (n = 2562). The incidence remained lower in the early antibiotic group after stepwise statistical adjustments for NICU (OR, 0.57; 95% CI, 0.35-0.94, P < .05) and other potential confounders (OR, 0.25; 95% CI, 0.12-0.47; P < .0001).

CONCLUSIONS

In this large international cohort of preterm VLBW infants, a small proportion of infants did not receive antibiotics just after birth, and these infants had a higher incidence of NEC. It is important to better understand the role of such variables as time, type, and duration of antibiotic treatment on NEC incidence, immune development, gut colonization, and antibiotic resistance in the NICU.

Medication Use During Pregnancy and Lactation in a Dutch Population

BACKGROUND:

Medication use during pregnancy and lactation can be unavoidable, but knowledge on safety for the fetus or breastfed infant is limited among patients and healthcare providers.

RESEARCH AIM:

This study aimed to determine (a) the prevalence of medication use in pregnant and lactating women in a tertiary academic center, (b) the types and safety of these medicines, and (c) the influence of medication use on initiation of breastfeeding.

METHODS:

This study used a cross-sectional survey among women ( N = 292) who underwent high-risk or low-risk deliveries. Data about their use of prescribed, over-the-counter, and homeopathic medication during pregnancy were obtained through a structured interview, followed by a questionnaire during lactation. Safety was classified according to the risk classification system from the Dutch Teratological Information Service.

RESULTS:

Overall, 95.5% of participants used medication. One third of participants used at least one medicine with an unknown risk for the fetus. Teratogenic medication was used by 6.5% of participants, whereas 29.5% used medication with a (suspected) pharmacological effect on the fetus. Lactation was initiated by 258 (88.7%) participants, of which 84.2% used medication while breastfeeding. In 3.8% of participants, this medication was classified unsafe, but none used medication with an unknown risk. One-third of the nonlactating participants decided not to initiate breastfeeding because of medication use. In 70% of participants, this decision was appropriate.

CONCLUSION:

The prevalence of overall use of medication in Dutch pregnant and lactating women admitted to a tertiary center was high. There is an urgent need for pharmacometric studies for determination of the safe use of the most frequently used medicines during pregnancy or lactation.

Nutrition During Pregnancy, Lactation and Early Childhood and its Implications for Maternal and Long-Term Child Health: The Early Nutrition Project Recommendations

BACKGROUND

A considerable body of evidence accumulated especially during the last decade, demonstrating that early nutrition and lifestyle have long-term effects on later health and disease ("developmental or metabolic programming").

METHODS

Researchers involved in the European Union funded international EarlyNutrition research project consolidated the scientific evidence base and existing recommendations to formulate consensus recommendations on nutrition and lifestyle before and during pregnancy, during infancy and early childhood that take long-term health impact into account. Systematic reviews were performed on published dietary guidelines, standards and recommendations, with special attention to long-term health consequences. In addition, systematic reviews of published systematic reviews on nutritional interventions or exposures in pregnancy and in infants and young children aged up to 3 years that describe effects on subsequent overweight, obesity and body composition were performed. Experts developed consensus recommendations incorporating the wide-ranging expertise from additional 33 stakeholders.

FINDINGS

Most current recommendations for pregnant women, particularly obese women, and for young children do not take long-term health consequences of early nutrition into account, although the available evidence for relevant consequences of lifestyle, diet and growth patterns in early life on later health and disease risk is strong.

INTERPRETATION

We present updated recommendations for optimized nutrition before and during pregnancy, during lactation, infancy and toddlerhood, with special reference to later health outcomes. These recommendations are developed for affluent populations, such as women and children in Europe, and should contribute to the primary prevention of obesity and associated non-communicable diseases.

Time to Full Enteral Feeding for Very Low-Birth-Weight Infants Varies Markedly Among Hospitals Worldwide But May Not Be Associated With Incidence of Necrotizing Enterocolitis: The NEOMUNE-NeoNutriNet Cohort Study

BACKGROUND

Transition to enteral feeding is difficult for very low-birth-weight (VLBW; ≤1500 g) infants, and optimal nutrition is important for clinical outcomes.

METHOD

Data on feeding practices and short-term clinical outcomes (growth, necrotizing enterocolitis [NEC], mortality) in VLBW infants were collected from 13 neonatal intensive care units (NICUs) in 5 continents (n = 2947). Specifically, 5 NICUs in Guangdong province in China (GD), mainly using formula feeding and slow feeding advancement (n = 1366), were compared with the remaining NICUs (non-GD, n = 1581, Oceania, Europe, United States, Taiwan, Africa) using mainly human milk with faster advancement rates.

RESULTS

Across NICUs, large differences were observed for time to reach full enteral feeding (TFF; 8-33 days), weight gain (5.0-14.6 g/kg/day), ∆z-scores (-0.54 to -1.64), incidence of NEC (1%-13%), and mortality (1%-18%). Adjusted for gestational age, GD units had longer TFF (26 vs 11 days), lower weight gain (8.7 vs 10.9 g/kg/day), and more days on antibiotics (17 vs 11 days; all P < .001) than non-GD units, but NEC incidence and mortality were similar.

CONCLUSION

Feeding practices for VLBW infants vary markedly around the world. Use of formula and long TFF in South China was associated with more use of antibiotics and slower weight gain, but apparently not with more NEC or higher mortality. Both infant- and hospital-related factors influence feeding practices for preterm infants. Multicenter, randomized controlled trials are required to identify the optimal feeding strategy during the first weeks of life.

Human milk peptides differentiate between the preterm and term infant and across varying lactational stages

Variations in endogenous peptide profiles, functionality, and the enzymes responsible for the formation of these peptides in human milk are understudied. Additionally, there is a lack of knowledge regarding peptides in donor human milk, which is used to feed preterm infants when mother's own milk is not (sufficiently) available. To assess this, 29 human milk samples from the Dutch Human Milk Bank were analyzed as three groups, preterm late lactation stage (LS) (n = 12), term early (n = 8) and term late LS (n = 9). Gestational age (GA) groups were defined as preterm (24-36 weeks) and term (≥37 weeks). LS was determined as days postpartum as early (16-36 days) or late (55-88 days). Peptides, analyzed by LC-MS/MS, and parent proteins (proteins from matched peptide sequences) were identified and quantified, after which peptide functionality and the enzymes responsible for protein cleavage were determined. A total of 16 different parent proteins were identified from human milk, with no differences by GA or LS. We identified 1104 endogenous peptides, of which, the majority were from the parent proteins β-casein, polymeric immunoglobulin receptor, α_s1-casein, osteopontin, and κ-casein. The absolute number of peptides differed by GA and LS with 30 and 41 differing sequences respectively (p < 0.05) Odds likelihood tests determined that 32 peptides had a predicted bioactive functionality, with no significant differences between groups. Enzyme prediction analysis showed that plasmin/trypsin enzymes most likely cleaved the identified human milk peptides. These results explain some of the variation in endogenous peptides in human milk, leading to future targets that may be studied for functionality.

Low- versus High-Dose and Early versus Late Parenteral Amino-Acid Administration in Very-Low-Birth-Weight Infants: A Systematic Review and Meta-Analysis

OBJECTIVES

Providing parenteral amino acids to very-low-birth-weight infants during the first weeks of life is critical for adequate growth and neurodevelopment. However, there is no consensus about what dose is appropriate or when to initiate supplementation. As a result, daily practice varies among neonatal intensive care units. The objective of our study was to determine the effects of early parenteral amino-acid supplementation (within 24 h of birth) versus later initiation and high dose (>3.0 g/kg/day) versus a lower dose on growth and morbidities.

METHODS

A systematic review and meta-analysis of publications identified by searching PubMed, EMBASE, and Cochrane databases was conducted. Randomized controlled studies were eligible if information on growth was available.

RESULTS

The search identified 14 studies. No differences were observed in growth or morbidity after early or high-dose amino-acid supplementation, but for several outcomes, meta-analysis was not possible due to study heterogeneity. Initiation of amino acids within the first 24 h of life appeared to be safe and well tolerated, and leads more rapidly to a positive nitrogen balance.

CONCLUSIONS

Administering a high dose (>3.0 g/kg/day) or an early dose (≤24 h) of parenteral amino acids is safe and well tolerated but does not offer significant benefits on growth. Further large-scale randomized controlled trials in preterm infants are needed to study the effects of early and high-dose amino acids on growth and morbidity more consistently and extensively.

Pasteurization Procedures for Donor Human Milk Affect Body Growth, Intestinal Structure, and Resistance against Bacterial Infections in Preterm Pigs

Background: Holder pasteurization (HP) destroys multiple bioactive factors in donor human milk (DM), and UV-C irradiation (UVC) is potentially a gentler method for pasteurizing DM for preterm infants.Objective: We investigated whether UVC-treated DM improves gut maturation and resistance toward bacterial infections relative to HP-treated DM.Methods: Bacteria, selected bioactive components, and markers of antioxidant capacity were measured in unpasteurized donor milk (UP), HP-treated milk, and UVC-treated milk (all from the same DM pool). Fifty-seven cesarean-delivered preterm pigs (91% gestation; ratio of males to females, 30:27) received decreasing volumes of parental nutrition (average 69 mL · kg^-1 · d^-1) and increasing volumes of the 3 DM diets (n = 19 each, average 89 mL · kg^-1 · d^-1) for 8-9 d. Body growth, gut structure and function, and systemic bacterial infection were evaluated.Results: A high bacterial load in the UP (6×10⁵ colony forming units/mL) was eliminated similarly by HP and UVC treatments. Relative to HP-treated milk, both UVC-treated milk and UP showed greater activities of lipase and alkaline phosphatase and concentrations of lactoferrin, secretory immunoglobulin A, xanthine dehydrogenase, and some antioxidant markers (all P < 0.05). The pigs fed UVC-treated milk and pigs fed UP showed higher relative weight gain than pigs fed HP-treated milk (5.4% and 3.5%), and fewer pigs fed UVC-treated milk had positive bacterial cultures in the bone marrow (28%) than pigs fed HP-treated milk (68%) (P < 0.05). Intestinal health was also improved in pigs fed UVC-treated milk compared with those fed HP-treated milk as indicated by a higher plasma citrulline concentration (36%) and villus height (38%) (P < 0.05) and a tendency for higher aminopeptidase N (48%) and claudin-4 (26%) concentrations in the distal intestine (P < 0.08). The gut microbiota composition was similar among groups except for greater proportions of Enterococcus in pigs fed UVC-treated milk than in pigs fed UP and those fed HP-treated milk in both cecum contents (20% and 10%) and distal intestinal mucosa (24% and 20%) (all P < 0.05).Conclusions: UVC is better than HP treatment in preserving bioactive factors in DM. UVC-treated milk may induce better weight gain, intestinal health, and resistance against bacterial infections as shown in preterm pigs as a model for DM-fed preterm infants.

Glucocorticoid Programming in Very Preterm Birth

Very preterm (i.e., <32 weeks of gestation) infants admitted to the neonatal intensive care unit are compromised in their abilities to respond adequately to common threats like hemodynamic changes and reduced energy supplies, which is partly attributable to adrenocortical insufficiency. Conversely, later in life, these infants show features of increased glucocorticoid bioactivity, such as abdominal fat distribution, raised blood pressure, insulin resistance and diabetes mellitus type 2. It has been suggested that the very preterm newborn responds to the adverse postnatal environment with a sustained elevation in hypothalamus-pituitary-adrenal axis activity that persists beyond infancy. This has implications for subsequent growth, body composition, metabolism, neurodevelopment and, ultimately, long-term disease risk. The mechanisms underpinning these associations are not fully elucidated yet. This review gives a brief summary of studies that investigated adrenocortical function in very preterm newborns and how the axis changes with age, as a possible explanation for the association between prematurity and long-term outcome.

Programming of the Hypothalamus-Pituitary-Adrenal Axis by Very Preterm Birth

BACKGROUND

Many very preterm (i.e., <32 weeks of gestation) newborns fail to mount an adequate adrenocortical response to stress or illness, termed relative adrenal insufficiency. Conversely, later in life these infants show features of increased glucocorticoid bioactivity, such as abdominal adiposity, insulin resistance, raised blood pressure, shorter stature and internalizing problem behavior.

SUMMARY

Studies suggested that very preterm newborns have impairments along multiple levels of the hypothalamus-pituitary-adrenal (HPA) axis. Among the impairment were defects in: (1) the pituitary responsiveness to exogenous corticotropin-releasing hormone, (2) 11β-hydroxylase activity, and (3) the interconversion between cortisol and inert cortisone. There is some evidence suggesting that later in life these infants have an increased basal secretion rate of cortisol and adrenal hyperandrogenism. However, the response to acute (psychosocial) stress was blunted rather than enhanced in them. The mechanisms explaining this switch in HPA axis activity are complex and not yet fully understood. Key Messages: Very preterm newborns have several impairments along the HPA axis that could impede an adequate adrenocortical response to stress or illness. Later in life, these infants are predisposed to increased HPA axis activity, which could partially explain their phenotype.

Breast-Milk Cortisol and Cortisone Concentrations Follow the Diurnal Rhythm of Maternal Hypothalamus-Pituitary-Adrenal Axis Activity

BACKGROUND

Very preterm infants often receive donor milk from mothers who deliver at term, but its composition differs from that of their own mother's milk. Because breast-milk glucocorticoids can support developing neonates, we explored concentration variability within and between mothers.

OBJECTIVE

We hypothesized that breast-milk glucocorticoid concentrations would be higher after very preterm delivery [gestational age (GA) <32 wk; study 1] and would follow the diurnal rhythm of maternal adrenocortical activity (study 2).

METHODS

Study 1 assessed differences in milk cortisol, cortisone, and the cortisone-to-(cortisol+cortisone) ratio of mothers who delivered at (median) GA: 28.6 wk or at term weekly during the first month postpartum. Study 2 assessed variations in milk cortisol, cortisone, and the cortisone-to-(cortisol+cortisone) ratio over 24 h, and tested Pearson correlations between milk and salivary concentrations in mothers who delivered at term (median GA: 38.9 wk) during week 4 postpartum. In these studies, foremilk glucocorticoids were measured by liquid chromatography-tandem mass spectrometry. Associations of milk cortisol, milk cortisone, and the milk cortisone-to-(cortisol+cortisone) ratio with prematurity (study 1) or collection time (study 2) were studied with longitudinal data analyses.

RESULTS

In study 1, giving birth to a very preterm infant was associated with reductions in milk cortisol and cortisone concentrations of 50% (β: 0.50; 95% CI: 0.26, 0.99; P = 0.05) and 53% (β: 0.53; 95% CI: 0.30, 0.93; P = 0.03), respectively, when adjusted for collection time. In study 2, concentrations of milk cortisol and cortisone were associated with collection time (both P < 0.01), peaking at ∼0700. Milk and salivary concentrations of cortisol (r = 0.92, P < 0.01) and cortisone (r = 0.93, P < 0.01) as well as the cortisone-to-(cortisol+cortisone) ratio (r = 0.64, P < 0.01) were correlated with one another.

CONCLUSIONS

Breast-milk glucocorticoid concentrations follow the diurnal rhythm of maternal hypothalamus-pituitary-adrenal axis activity and are lower in mothers who deliver very preterm.

Effect of Donor Milk on Severe Infections and Mortality in Very Low-Birth-Weight Infants: The Early Nutrition Study Randomized Clinical Trial

IMPORTANCE

Infections and necrotizing enterocolitis, major causes of mortality and morbidity in preterm infants, are reduced in infants fed their own mother's milk when compared with formula. When own mother's milk is not available, human donor milk is considered a good alternative, albeit an expensive one. However, most infants at modern neonatal intensive care units are predominantly fed with own mother's milk. The benefits of add-on donor milk over formula are not clear.

OBJECTIVE

To determine whether providing donor milk instead of formula as supplemental feeding whenever own mother's milk is insufficiently available during the first 10 days of life reduces the incidence of serious infection, necrotizing enterocolitis, and mortality.

DESIGN, SETTINGS, AND PARTICIPANTS

The Early Nutrition Study was a multicenter, double-blind randomized clinical trial in very low-birth-weight infants (birth weight <1500 g) admitted to 1 of 6 neonatal intensive care units in the Netherlands from March 30, 2012, through August 17, 2014. Intent-to-treat analysis was performed.

INTERVENTIONS

Infants received pasteurized donor milk or preterm formula during the first 10 days of life if own mother's milk was not (sufficiently) available.

MAIN OUTCOMES AND MEASURES

The primary end point was cumulative occurrence of serious infection (sepsis or meningitis), necrotizing enterocolitis, or mortality during the first 60 days of life.

RESULTS

A total of 930 infants were screened for inclusion; 557 were excluded, resulting in 373 infants (183 receiving donor milk and 190 receiving formula) who were evaluated by intent-to-treat analysis (median birth weight, 1066 g; mean gestational age, 28.4 weeks). Own mother's milk comprised 89.1% and 84.5% of total mean intake during the intervention period for the donor milk and formula groups, respectively. The incidence of the combined outcome was not different (85 [44.7%] [formula] vs 77 [42.1%] [donor milk]; mean difference, 2.6%; 95% CI, -12.7% to 7.4%). The adjusted hazard ratio was 0.87 (95% CI, 0.63-1.19; P = .37).

CONCLUSIONS AND RELEVANCE

In the current study, pasteurized donor milk and preterm formula as supplemental feeding during the first 10 days of life yielded similar short-term outcomes in very low-birth-weight infants regarding safety and efficacy when own mother's milk availability was insufficient. Future studies investigating longer duration of use of human donor milk on short-term and long-term outcomes are necessary.

TRIAL REGISTRATION

trialregister.nl Identifier: NTR3225.

Changes over lactation in breast milk serum proteins involved in the maturation of immune and digestive system of the infant

Here we provide data from shot-gun proteomics, using filtered-aided sample preparation (FASP), dimethyl labeling and LC-MS/MS, to quantify the changes in the repertoire of human milk proteins over lactation. Milk serum proteins were analyzed at week 1, 2, 3 4, 8, 16, and 24 in milk from four individual mothers. A total of 247 proteins were identified, of which 200 proteins were quantified. The data supplied in this article supports the accompanying publication (Zhang et al., 2006) [1]. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium (Vizcaíno et al., 2016) [2] via the PRIDE partner repository with the dataset identifier PXD003465.

Changes over lactation in breast milk serum proteins involved in the maturation of immune and digestive system of the infant

To objective of this study was to better understand the biological functions of breast milk proteins in relation to the growth and development of infants over the first six months of life. Breast milk samples from four individual women collected at seven time points in the first six months after delivery were analyzed by filter aided sample preparation and dimethyl labeling combined with liquid chromatography tandem mass spectrometry. A total of 247 and 200 milk serum proteins were identified and quantified, respectively. The milk serum proteome showed a high similarity (80% overlap) on the qualitative level between women and over lactation. The quantitative changes in milk serum proteins were mainly caused by three groups of proteins, enzymes, and transport and immunity proteins. Of these 21 significantly changed proteins, 30% were transport proteins, such as serum albumin and fatty acid binding protein, which are both involved in transporting nutrients to the infant. The decrease of the enzyme bile salt-activated lipase as well as the immunity proteins immunoglobulins and lactoferrin coincide with the gradual maturation of the digestive and immune system of infants. The human milk serum proteome didn't differ qualitatively but it did quantitatively, both between mothers and as lactation advanced. The changes of the breast milk serum proteome over lactation corresponded with the development of the digestive and immune system of infants.

BIOLOGICAL SIGNIFICANCE

Breast milk proteins provide nutrition, but also contribute to healthy development of infants. Despite the previously reported large number of identified breast milk proteins and their changes over lactation, less is known on the changes of these proteins in individual mothers. This study is the first to determine the qualitative and quantitative changes of milk proteome over lactation between individual mothers. The results indicate that the differences in the milk proteome between individual mothers are more related to the quantitative level than qualitative level. The correlation between the changes of milk proteins and the gradual maturation of the gastrointestinal tract and immune system in infants, contributes to a better understanding of the biological functions of human milk proteins for the growth and development of infants.