Smell and taste in the preterm infant

Effects of Gustatory and Olfactory Stimulation on Feeding Outcomes in Preterm Infants: A Systematic Review and Meta-Analysis

BACKGROUND

Few primary studies have examined the impact of olfactory and gustatory stimulation on premature infants, and variability exists in reported outcomes.

PURPOSE

To explore the effects of olfactory and gustatory stimulation on feeding outcomes in preterm infants.

DATA SOURCES

A literature search was conducted in 4 databases (CENTRAL, PubMed, Embase, CINAHL) from the inception of the databases to May 2024.

STUDY SELECTION

Randomized controlled trials (RCTs) or quasi-RCTs to explore the effects of olfactory and gustatory stimulation on feeding outcomes in preterm infants were included.

DATA EXTRACTION

Two reviewers independently extracted data from the included studies and completed the form designed for data extraction.

RESULTS

Eleven RCTs and quasi-RCTs comprising 1009 preterm infants were included. Meta-analysis found that olfactory and gustatory stimulation significantly shortened the time to reach full oral feeds ( days ) (mean difference [MD]: -2.52, 95% confidence interval [CI]: -3.88 to -1.16, P = .0003), while they had no significant differences in time to achieve full enteral feeds ( days ), postmenstrual age (PMA) at the removal of the nasogastric tube ( weeks ), weight at discharge ( grams ), weight gain ( grams ), head circumference at discharge ( cm ), length at discharge ( cm ), total duration of parenteral nutrition ( days ), necrotizing enterocolitis, hospitalization duration ( days ), PMA at discharge ( weeks ).

IMPLICATIONS FOR PRACTICE AND RESEARCH

Large sample, multicenter studies are needed to demonstrate the effectiveness of olfactory and gustatory stimulation on feeding outcomes in preterm infants.

Does Maternal Diet Influence Future Infant Taste and Odor Preferences? A Critical Analysis

The dietary choices a mother makes during pregnancy offer her developing fetus its earliest exposure to the family's culinary preferences. This comprehensive literature review synthesizes five decades of research, which has provided valuable insights into fetal flavor learning. Converging evidence across various species supports the functionality of fetal chemoreceptive systems by the end of gestation, enabling the detection of an extensive array of chemosensory cues derived from the maternal diet and transmitted to the amniotic fluid. The fetus effectively encodes these flavors, resulting in their enhanced acceptance after birth. While existing studies predominantly concentrate on fetal learning about odor volatiles, limited evidence suggests a capacity for learning about gustatory (i.e., taste) properties. Examining whether these prenatal odor, taste, and flavor experiences translate into enduring shifts in dietary behaviors beyond weaning remains a crucial avenue for further investigation.

Exposure to the smell and taste of milk to accelerate feeding in preterm infants

BACKGROUND

Preterm infants (born before 37 weeks' gestation) are often unable to co-ordinate sucking, swallowing, and breathing for oral feeding because of their immaturity. In such cases, initial nutrition is provided by orogastric or nasogastric tube feeding. Feeding intolerance is common and can delay attainment of full enteral and sucking feeds, prolonging the need for nutritional support and the hospital stay. Smell and taste play an important role in the activation of physiological pre-absorptive processes that contribute to food digestion and absorption. However, during tube feeding, milk bypasses the nasal and oral cavities, limiting exposure to the smell and taste of milk. Provision of the smell and taste of milk with tube feeds offers a non-invasive and low-cost intervention that, if effective in accelerating the transition to enteral feeds and subsequently to sucking feeds, would bring considerable advantages to infants, their families, and healthcare systems.

OBJECTIVES

To assess whether exposure to the smell or taste (or both) of breastmilk or formula administered with tube feeds can accelerate the transition to full sucking feeds without adverse effects in preterm infants.

SEARCH METHODS

We conducted searches in CENTRAL, MEDLINE, Embase, CINAHL, and Epistemonikos to 26 April 2023. We also searched clinical trial databases and conference proceedings.

SELECTION CRITERIA

We included randomised and quasi-randomised studies that evaluated exposure versus no exposure to the smell or taste of milk (or both) immediately before or at the time of tube feeds.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed risk of bias, and extracted data according to Cochrane Neonatal methodology. We performed meta-analyses using risk ratios (RRs) for dichotomous data and mean differences (MDs) for continuous data, with their respective 95% confidence intervals (CIs). We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included eight studies (1277 preterm infants). Seven studies (1244 infants) contributed data for meta-analysis. The evidence suggests that exposure to the smell and taste of milk with tube feeds has little to no effect on time taken to reach full sucking feeds (MD -1.07 days, 95% CI -2.63 to 0.50; 3 studies, 662 infants; very low-certainty evidence). Two studies reported no adverse effects related to the intervention. The intervention may have little to no effect on duration of parenteral nutrition (MD 0.23 days, 95% CI -0.24 to 0.71; 3 studies, 977 infants; low-certainty evidence), time to reach full enteral feeds (MD -0.16 days, 95% CI -0.45 to 0.12; 1 study, 736 infants; very low-certainty evidence) or risk of necrotising enterocolitis (RR 0.93, 95% CI 0.47 to 1.84; 2 studies, 435 infants; low-certainty evidence), although the evidence for time to reach full enteral feeds is very uncertain. Exposure to the smell and taste of milk with tube feeds probably has little to no effect on risk of late infection (RR 1.14, 95% CI 0.74 to 1.75; 2 studies, 436 infants; moderate-certainty evidence). There were no data available to assess feeding intolerance. The included studies had small sample sizes and methodological limitations, including unclear or lack of randomisation (four studies), lack of blinding of participants and personnel (five studies), unclear or lack of blinding of the outcome assessor (all eight studies), and different inclusion criteria and methods of administering the interventions.

AUTHORS' CONCLUSIONS

The results of our meta-analyses suggest that exposure to the smell and taste of milk with tube feeds may have little to no effect on time to reach full sucking feeds and time to reach full enteral feeds. We found no clear difference between exposure and no exposure to the smell or taste of milk on safety outcomes (adverse effects, necrotising enterocolitis, and late infection). Results from one ongoing study and two studies awaiting classification may alter the conclusions of this review. Future research should examine the effect of exposing preterm infants to the smell and taste of milk with tube feeds on health outcomes during hospitalisation, such as attainment of feeding skills, safety, feed tolerance, infection, and growth. Future studies should be powered to detect the effect of the intervention in infants of different gestational ages and on each sex separately. It is also important to determine the optimal method, frequency, and duration of exposure.

Effects of olfactory and/or gustatory stimuli on feeding of preterm infants: A systematic review and meta-analysis

AIM

To evaluate the effect of olfactory and/or gustatory stimulation interventions on feeding outcomes in preterm infants.

METHODS

We conducted systematic searches across various academic databases, including PubMed, Embase, Web of Science, the Cochrane Library, the Chinese Biomedical Literature Service System, China National Knowledge Infrastructure, the Wanfang Database, and the Wipu Database. These searches aimed to identify randomized controlled trials investigating the impact of olfactory and/or gustatory stimulation on preterm infants. The search period spanned from the inception of the databases until December 2022. Two independent evaluators autonomously reviewed the literature, extracted pertinent data, assessed the quality of the included studies, and conducted a meta-analysis using RevMan 5.3 software.

RESULTS

A total of 7 randomized controlled trials or quasi-experimental studies were included, with a total of 871 participants. Olfactory and gustatory stimulation demonstrated a reduction in the time to full enteral feeds in preterm infants when compared to usual care (MD = -1.60 days; 95% CI = -2.31, -0.89; p<0.0001). No substantial evidence was identified regarding the influence of olfactory and gustatory stimulation on the duration of gastric tube placement, length of hospitalization, incidence of necrotizing enterocolitis, or occurrence of spontaneous bowel perforation in preterm infants.

CONCLUSIONS

Olfactory and gustatory stimulation show potential benefits for preterm infants. However, due to the low to very low level of certainty associated with the available data, our ability to assess the effects is limited. Further trials and studies are essential to enhance our understanding of the mechanisms and effectiveness of olfactory and gustatory stimulation therapies.

Should Fathers Also Do Kangaroo Care?

OBJECTIVES

The aim of the study is to compare the effect of maternal and paternal Kangaroo care (KC) on vital signs and cerebral oxygen saturation (rSO2) parameters.

METHODS

This randomized study included 35 preterm infants born at 32 weeks gestation or earlier. The body temperature, respiratory rate, heart rate, oxygen saturation (sPO2), and cerebral oxygen saturation (rSO2) were measured at the postnatal 35th week of gestation during three periods: in the incubator before KC, during KC with the mother or father, and in the incubator after KC. The measured parameters of the three periods were compared within each group (mother or father) and between the groups (mother and father).

RESULTS

There was no statistically significant difference between the vital signs during the three periods, both in the mother and father groups, and between the parents.The rSO2 values increased significantly in both parents (p <0.001) during and after KC. When we compared parents, rSO2 values were significantly higher during (p = 0.015) and after (p = 0.046) mother KC.

CONCLUSION

The difference between M-KC and F-KC can be ignored as the cerebral near infra-red spectroscopy values are within normal limits. The active participation of fathers in KC should be encouraged by health professionals in all NICUs.

KEY POINTS

· * The vital signs during and after kangaroo care, both in the mother and father groups, were similar.. · * The rSO2 values increased significantly in both parents during and after kangaroo care, favoring the mother.. · * This difference can be ignored as the cerebral near-infra-red spectroscopy values are within normal limits in both groups, and the participation of fathers in kangaroo care should be encouraged..

The Effect of Lullabies and Classical Music on Preterm Neonates' Cerebral Oxygenation, Vital Signs, and Comfort During Orogastric Tube Feeding: A Randomized Controlled Trial

OBJECTIVE

This study investigated the effect of lullabies and classical music on preterm neonates' cerebral oxygenation, vital signs, and comfort during orogastric (OG) tube feeding.

METHODS

This was a parallel-group pretest-posttest randomized controlled study. The research was conducted between December 2020 and May 2022. The sample consisted of 51 preterm neonates hospitalized in the neonatal intensive care unit (NICU) of Selçuk University Faculty of Medicine Hospital in Konya, Türkiye. Participants were randomized into three groups (17 preterm infants in each group). The first group listened to lullabies sung by their mothers and the second group listened to classical music during OG tube feeding. The control group received routine care with no music. Data were collected using a Neonatal Identification Information Form, Physiological Parameters and rSO2 Monitoring Form, and the Newborn Comfort Behavior Scale (Comfort-Neo). The study was registered on the ClinicalTrials database (NCT05333575).

RESULTS

The lullaby group had stable peak heart rates and oxygen saturation levels (p = .002). Both lullaby and classical music groups had significantly higher cerebral oxygenation levels than the control group. The classical music group had the highest cerebral oxygenation level (p = .001). Both lullaby and classical music groups had significantly higher mean Comfort-Neo scores than the control group. The classical music group had the highest mean Comfort-Neo score (p = .040).

CONCLUSION

Preterm neonates who listen to lullabies and classical music are likely to have higher cerebral oxygen and comfort levels. Listening to lullabies helps stabilize vital signs. These results suggest that healthcare professionals should encourage parents to get their preterm neonates to listen to lullabies and classical music.

Developmental care pathway for hospitalised infants with CHD: on behalf of the Cardiac Newborn Neuroprotective Network, a Special Interest Group of the Cardiac Neurodevelopmental Outcome Collaborative

Infants and children born with CHD are at significant risk for neurodevelopmental delays and abnormalities. Individualised developmental care is widely recognised as best practice to support early neurodevelopment for medically fragile infants born premature or requiring surgical intervention after birth. However, wide variability in clinical practice is consistently demonstrated in units caring for infants with CHD. The Cardiac Newborn Neuroprotective Network, a Special Interest Group of the Cardiac Neurodevelopmental Outcome Collaborative, formed a working group of experts to create an evidence-based developmental care pathway to guide clinical practice in hospital settings caring for infants with CHD. The clinical pathway, "Developmental Care Pathway for Hospitalized Infants with Congenital Heart Disease," includes recommendations for standardised developmental assessment, parent mental health screening, and the implementation of a daily developmental care bundle, which incorporates individualised assessments and interventions tailored to meet the needs of this unique infant population and their families. Hospitals caring for infants with CHD are encouraged to adopt this developmental care pathway and track metrics and outcomes using a quality improvement framework.

Analysis for different flavor compounds in mature milk from human and livestock animals by GC × GC-TOFMS

Breast milk plays a crucial role in the taste development of infants, which cannot be replicated by other mammalian milk or formulas. This study aimed to identify and characterize the flavor substances in 15 different types of milk and analyze the differences among them. The results showed that human milk contained high levels of esters, particularly fatty acid ethyl esters, which contribute to its unique flavor. The four substances that had the highest flavor contribution in all species were identified as 2,3-butanedione, trimethylamine, isophorone, and acetaldehyde. Furthermore, the analysis of differences revealed that thermal-oxidation of lipids could explain the variation between human milk and other species in terms of flavor compounds. The key differential flavor compounds identified in milk from all species were trimethylamine, propanal, 1-pentanol, pyridine 2-methyl, and 2-butanone. These findings can potentially aid in developing formulas that better meet the taste needs of infants.

Drug exposure during pregnancy: Current understanding and approaches to measure maternal-fetal drug exposure

Prescription drug use is prevalent during pregnancy, yet there is limited knowledge about maternal-fetal safety and efficacy of this drug use because pregnant individuals have historically been excluded from clinical trials. Underrepresentation has resulted in a lack of data available to estimate or predict fetal drug exposure. Approaches to study fetal drug pharmacology are limited and must be evaluated for feasibility and accuracy. Anatomic and physiological changes throughout pregnancy fluctuate based on gestational age and can affect drug pharmacokinetics (PK) for both mother and fetus. Drug concentrations have been studied throughout different stages of gestation and at or following delivery in tissue and fluid biospecimens. Sampling amniotic fluid, umbilical cord blood, placental tissue, meconium, umbilical cord tissue, and neonatal hair present surrogate options to quantify and characterize fetal drug exposure. These sampling methods can be applied to all therapeutics including small molecule drugs, large molecule drugs, conjugated nanoparticles, and chemical exposures. Alternative approaches to determine PK have been explored, including physiologically based PK modeling, in vitro methods, and traditional animal models. These alternative approaches along with convenience sampling of tissue or fluid biospecimens can address challenges in studying maternal-fetal pharmacology. In this narrative review, we 1) present an overview of the current understanding of maternal-fetal drug exposure; 2) discuss biospecimen-guided sampling design and methods for measuring fetal drug concentrations throughout gestation; and 3) propose methods for advancing pharmacology research in the maternal-fetal population.

The frontal sharp transient in newborns: An endogenous neurobiomarker concomitant to the physiological and critical transitional period around delivery?

The frontal sharp transient (FST) consists of transient electrical activity recorded around the transitional period from the in to ex utero environment. Although its positive predictive value is assumed, nothing is known about its functionality or origin. The objectives were (i) to define its characteristics and (ii) to develop functional hypothesis. The 128-channels high-resolution electroencephalograms of 20 healthy newborns (37.1-41.6 weeks) were studied. The morphological and time-frequency characteristics of 418 FSTs were analyzed. The source localization of the FSTs was obtained using a finite element head model (5 layers and fontanels) and various source localization methods (distributed and dipolar). The characteristics (duration, slopes, and amplitude) and the localization of FSTs were not modulated by the huge developmental neuronal processes that occur during the very last period of gestation. The sources were located beneath the ventral median part of the frontal lobe around the interhemispheric fissure, suggesting that the olfactory bulbs and orbitofrontal cortex, essential in olfaction and the mother-infant attachment relationship, are likely candidates for the generation of FSTs. FSTs may contribute to the implementation of the functionalities of brain structures involved in the higher-order processing necessary for survival ahead of delivery, with a genetic fingerprint.

Development of Sensory Processing in Premature Infants and Implications for Evidence-Based Music Therapy in the NICU

The purpose of this article is to provide an overview of the development of sensory processing in premature infants with implications for music therapists providing evidence-based care in a NICU. An overview of sensory processing and sensory processing disorders in premature infants is included, with specific emphasis on development of sensory systems of premature infants. Implications for developmentally appropriate music as therapy for premature infants are identified. Evidence-based NICU-MT can be combined with nursing care to reduce the risks of sensory processing disorder for the developing premature infant.

Fetal programming of human energy homeostasis brain networks: Issues and considerations

In this paper, we present a transdisciplinary framework and testable hypotheses regarding the process of fetal programming of energy homeostasis brain circuitry. Our model proposes that key aspects of energy homeostasis brain circuitry already are functional by the time of birth (with substantial interindividual variation); that this phenotypic variation at birth is an important determinant of subsequent susceptibility for energy imbalance and childhood obesity risk; and that this brain circuitry exhibits developmental plasticity, in that it is influenced by conditions during intrauterine life, particularly maternal-placental-fetal endocrine, immune/inflammatory, and metabolic processes and their upstream determinants. We review evidence that supports the scientific premise for each element of this formulation, identify future research directions, particularly recent advances that may facilitate a better quantification of the ontogeny of energy homeostasis brain networks, highlight animal and in vitro-based approaches that may better address the determinants of interindividual variation in energy homeostasis brain networks, and discuss the implications of this formulation for the development of strategies targeted towards the primary prevention of childhood obesity.

Efficacy of Breast Milk Olfactory and Gustatory Interventions on Neonates’ Biobehavioral Responses to Pain during Heel Prick Procedures

This study aimed to evaluate the efficacy of breast milk odor either alone or in combination with breast milk taste (via syringe-feeding) to alleviate neonates’ biobehavioral responses to pain during heel-prick procedures. This prospective randomized controlled trial recruited 114 neonates by convenience sampling from a newborn unit of a medical center in Taiwan. Neonates were randomly assigned to three groups: control (gentle touch + human voice), control + breast milk odor, and control + breast milk odor + breast milk taste. Heart rate, oxygen saturation, and voice recordings of crying were measured across heel-prick procedures: baseline, no stimuli (stage 0); during heel prick (Stages 1–4); and recovery (Stages 5–10). Generalized estimating equations and Kaplan–Meier survival analysis compared differences in changes between groups for heart rate, oxygen saturation, and time to crying cessation. Changes in mean heart rate and oxygen saturation in neonates receiving breast milk odor or breast milk odor + breast milk taste were significantly less than those at the corresponding stage for the control group. Among neonates receiving breast milk odor or breast milk odor + breast milk taste, hazard rate ratios for crying cessation were 3.016 and 6.466, respectively. Mother’s breast milk olfactory and gustatory interventions could stabilize the biobehavioral responses to pain during heel prick procedures in neonates.

Breastmilk as a Multisensory Intervention for Relieving Pain during Newborn Screening Procedures: A Randomized Control Trial

The study aim was to explore the effects of multisensory breastmilk interventions on short-term pain of infants during newborn screening. This is a randomized controlled trial. A total of 120 newborns were recruited and assigned by randomization to one of three treatment conditions: Condition 1 = routine care (gentle touch + verbal comfort); Condition 2 = breastmilk odor + routine care; or Condition 3 = breastmilk odor + taste + routine care. Pain was scored with the Neonatal Infant Pain Scale (NIPS). Data were collected from video recordings at 1 min intervals over the 11 phases of heel sticks: phase 1, 5 min before heel stick without stimuli (baseline); phase 2 to phase 6 (during heel stick); and phase 7 to phase 11 (recovery). Generalized estimating equations compared differences in pain scores for newborns over phases among the three conditions. Compared with the routine care, provision of the odor and taste of breastmilk reduce NIPS scores during heel sticks (B = −4.36, SE = 0.45, p < 0.001 [phase₆]), and during recovery (B = −3.29, SE = 0.42, p < 0.001 [phase₇]). Our findings provide new data, which supports the use of multisensory interventions that include breastmilk odor and taste in combination with gentle touch and verbal comfort to relieve pain in infants undergoing newborn screening.

Olfactory Cues in Infant Feeds: Volatile Profiles of Different Milks Fed to Preterm Infants

Background: Smell is determined by odor-active volatile compounds that bind to specific olfactory receptors, allowing us to discriminate different smells. Olfactory stimulation may assist with digestion and metabolism of feeds in the neonate by activation of the cephalic phase response of digestion. Infants' physiological responses to the smell of different milks suggest they can distinguish between breastmilk and infant formula. We aimed to describe the profile of volatile compounds in preterm breastmilk and investigate how this differed from that of other preterm infant feeding options including pasteurized donor breastmilk, breastmilk with bovine milk-based fortifier, human milk-based products and various infant formulas. Methods: Forty-seven milk samples (13 different infant formulas and 34 human milk-based samples) were analyzed. Volatile compounds were extracted using Solid Phase Micro Extraction. Identification and relative quantification were carried out by Gas Chromatography with Mass Spectrometry. Principal Component Analysis (PCA) and one-way Analysis of Variance (ANOVA) with Tukey's HSD (parametric data) or Conover's post-hoc test (non-parametric data) were used as appropriate to explore differences in volatile profiles among milk types. Results: In total, 122 compounds were identified. Breastmilk containing bovine milk-based fortifier presented the highest number of compounds (109) and liquid formula the lowest (70). The profile of volatile compounds varied with 51 compounds significantly different (adjusted p < 0.001) among milk types. PCA explained 47% of variability. Compared to preterm breastmilk, the profile of volatile compounds in breastmilk with added bovine milk-based fortifier was marked by presence of fatty acids and their esters, ketones and aldehydes; infant formulas were characterized by alkyls, aldehydes and furans, and human milk-based products presented high concentrations of aromatic hydrocarbons, terpenoids and specific fatty acids. Conclusions: Sensory-active products of fatty acid oxidation are the major contributors to olfactory cues in infant feeds. Analysis of volatile compounds might be useful for monitoring quality of milk and detection of oxidation products and environmental contaminants. Further research is needed to determine whether these different volatile compounds have biological or physiological effects in nutrition of preterm infants.

Pain Control with Lavender Oil in Premature Infants: A Double-Blind Randomized Controlled Study

Objectives: Aromatherapy has become popular in pain control in recent years compared with other complementary methods. Lavender (Lavandula angustifolia Miller) is a fragrant essential oil used in aromatherapy for its antibacterial, antifungal, muscle-relaxing, and analgesic effects. The smell of lavender oil, known for its soothing effect on adults, has not been adequately investigated in regards to pain control in premature infants. The purpose of our study was to assign the effect of the scent of lavender oil on pain in preterm infants during heel lancing. Design: A double-blind randomized controlled clinical study. Settings/Location: The study was conducted in a third-level neonatal intensive care unit of Bezmialem Vakif University Hospital from March 2019 to November 2019. It consisted of two groups. Subjects: Sixty-one premature babies (24-37 weeks of gestation) were enrolled in the study. Interventions: Heel stick sampling for metabolic screening was used for both study groups. The interventions were performed by two experienced nurses. Heart rate, oxygen saturation, and the baby's facial expression were recorded by a camera 3 min before the intervention, during the sampling, and 3 min after the procedure. After collecting the data, the head researcher and the assistant researcher separately watched the videos and scored them by using the Premature Infant Pain Profile-Revised (PIPP-R). Outcome measures: The difference of pain scores (PIIP-R) between two groups. Results: There was a statistically significant difference between the two groups in terms of PIPP-R scores during and after the sampling (p = 0.008 and p = 0.03 respectively). The PIPP-R scores at the beginning of the procedure were not found to be significantly different between the groups (p > 0.05). Conclusions: Inhalation of lavender scent is effective in pain control in premature infants. It is safe and low cost; it does not interfere with medical care.

How babies learn: The autonomic socioemotional reflex

BACKGROUND

Human and animal research has long documented the negative effects of early traumatic events on long-term development and socioemotional behavior. Yet, how and where the body stores these memories remains unclear. Current theories propose that the brain stores such memory in the subcortical limbic system. However, a clear theory of change with testable hypothesis has yet to emerge.

AIMS

In this paper, we review the classical Pavlovian conditioning learning tradition, along with its functional variant. Then, we review calming cycle theory, which builds upon the idea that mother/infant learning is distinct from other types of learning, requiring a new set of assumptions in light of functional Pavlovian conditioning.

CONCLUSION

Calming cycle theory states that learning of behaviors associated with subcortical autonomic physiology is separate and distinct from learning of behaviors associated with cortical physiology. Mother/infant autonomic learning starts in the uterine environment via functional Pavlovian co-conditioning that is stored as conditional reflexes within the dyad's autonomic nervous systems. These reflexes are preserved transnatally as autonomic socioemotional reflexes (ASRs), which can be used to monitor mother-infant relational health. The functional Pavlovian co-conditioning mechanism can be exploited to change the physiological/behavioral reflex response. The theory provides a well established learning mechanism, a theory of change and a method of change, along with a set of hypotheses with which to test the theory. We present evidence from a randomized controlled trial with prematurely born infants and their mothers that supports calming cycle theory.

Fetal Alcohol Programming of Subsequent Alcohol Affinity: A Review Based on Preclinical, Clinical and Epidemiological Studies

The anatomo-physiological disruptions inherent to different categories of the Fetal Alcohol Spectrum Disorder do not encompass all the negative consequences derived from intrauterine ethanol (EtOH) exposure. Preclinical, clinical and epidemiological studies show that prenatal EtOH exposure also results in early programming of alcohol affinity. This affinity has been addressed through the examination of how EtOH prenatally exposed organisms recognize and prefer the drug’s chemosensory cues and their predisposition to exhibit heightened voluntary EtOH intake during infancy and adolescence. In altricial species these processes are determined by the interaction of at least three factors during stages equivalent to the 2nd and 3rd human gestational trimester: (i) fetal processing of the drug’s olfactory and gustatory attributes present in the prenatal milieu; (ii) EtOH’s recruitment of central reinforcing effects that also imply progressive sensitization to the drug’s motivational properties; and (iii) an associative learning process involving the prior two factors. This Pavlovian learning phenomenon is dependent upon the recruitment of the opioid system and studies also indicate a significant role of EtOH’s principal metabolite (acetaldehyde, ACD) which is rapidly generated in the brain via the catalase system. The central and rapid accumulation of this metabolite represents a major factor involved in the process of fetal alcohol programming. According to recent investigations, it appears that ACD exerts early positive reinforcing consequences and antianxiety effects (negative reinforcement). Finally, this review also acknowledges human clinical and epidemiological studies indicating that moderate and binge-like drinking episodes during gestation result in neonatal recognition of EtOH’s chemosensory properties coupled with a preference towards these cues. As a whole, the studies under discussion emphasize the notion that even subteratogenic EtOH exposure during fetal life seizes early functional sensory and learning capabilities that pathologically shape subsequent physiological and behavioral reactivity towards the drug.

Impact of prematurity on neurodevelopment

The consequences of prematurity on brain functional development are numerous and diverse, and impact all brain functions at different levels. Prematurity occurs between 22 and 36 weeks of gestation. This period is marked by extreme dynamics in the physiologic maturation, structural, and functional processes. These different processes appear sequentially or simultaneously. They are dependent on genetic and/or environmental factors. Disturbance of these processes or of the fine-tuning between them, when caring for premature children, is likely to induce disturbances in the structural and functional development of the immature neural networks. These will appear as impairments in learning skills progress and are likely to have a lasting impact on the development of children born prematurely. The level of severity depends on the initial alteration, whether structural or functional. In this chapter, after having briefly reviewed the neurodevelopmental, structural, and functional processes, we describe, in a nonexhaustive manner, the impact of prematurity on the different brain, motor, sensory, and cognitive functions.

Exposure to the smell and taste of milk to accelerate feeding in preterm infants

BACKGROUND

Preterm infants are often unable to co-ordinate sucking, swallowing and breathing for oral feeding because of their immaturity; in such cases, initial nutrition is provided by orogastric or nasogastric tube feeding. Feed intolerance is common and can delay attainment of full enteral feeds and sucking feeds, which prolongs the need for intravenous nutrition and hospital stay. Smell and taste play an important role in the activation of physiological pre-absorptive processes that contribute to food digestion and absorption. However, during tube feedings, milk bypasses the nasal and oral cavities, which limits exposure to the smell and taste of milk. Provision of the smell and taste of milk with tube feedings is non-invasive and inexpensive; and if it does accelerate the transition to enteral feeds, and then to sucking feeds, it would be of considerable potential benefit to infants, their families, and the healthcare system.

OBJECTIVES

To assess whether exposure to the smell or taste (or both) of milk administered with tube feedings can accelerate progress to full sucking feeds without adverse effects in preterm infants.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2018, Issue 5), MEDLINE via PubMed (1966 to 1 June 2018), Embase (1980 to 1 June 2018), and CINAHL (1982 to 1 June 2018). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised and quasi-randomised trials.

SELECTION CRITERIA

We included randomised and quasi-randomised studies that compared the provision of the smell or taste of milk (or both) immediately before or at the time of tube feedings, with no provision of smell or taste.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data according to Cochrane Neonatal methodology; they also assessed risk of bias, and the quality of evidence at the outcome level using the GRADE approach. We performed meta-analyses using risk ratio (RR) for dichotomous data and mean difference (MD) for continuous data, with their respective 95% confidence intervals (CIs).

MAIN RESULTS

Three trials involving a total of 161 preterm infants were included in this review, but only two trials (131 infants) contributed data for meta-analysis. There was no evidence of a clear effect of exposure to the smell and taste of milk with tube feedings on time taken to reach full sucking feeds (MD -2.57 days, 95% CI -5.15 to 0.02; I2 = 17%; 2 trials, 131 infants; very low-quality evidence). One trial reported no adverse effects. There was no evidence of a clear effect of exposure to the smell and taste of milk on the following outcomes: time taken to reach full enteral feeds (MD -1.57 days, 95% CI -6.25 to 3.11; 1 trial, 51 infants; very low-quality evidence), duration of parenteral nutrition (MD -2.20 days, 95% CI -9.49 to 5.09; 1 trial, 51 infants; very low-quality evidence), incidence of necrotising enterocolitis (RR 0.62, 95% CI 0.15 to 2.48; 1 trial, 51 infants; low-quality evidence), and late infection (RR 2.46, 95% CI 0.27 to 22.13; 1 trial, 51 infants; low-quality evidence). There was very low-quality evidence demonstrating that exposure to the smell and taste of milk decreased duration of hospitalisation by almost four days (MD -3.89 days, 95% CI -7.03 to -0.75; I2 = 51%; 2 trials, 131 infants). In two trials, an increased growth velocity was noted in infants exposed to the intervention, but we were unable to combine data to perform meta-analysis. No data were available to assess feed intolerance and rates of exclusive breastfeeding at discharge. Included trials were small and had methodological limitations including lack of randomisation (one trial), lack of blinding, and different inclusion criteria and administration of the interventions.

AUTHORS' CONCLUSIONS

Evidence from two trials suggests that exposure to the smell and taste of milk with tube feedings has no clear effect on time taken to reach full sucking feeds, but it may decrease length of hospitalisation. However, these results are uncertain due to the very low quality of the evidence. There is also limited evidence about the impact on other important clinical outcomes and on safety. Future research should examine the effect of exposure to the smell and taste of milk with tube feedings on clinical outcomes during hospitalisation, such as attainment of full enteral and sucking feeds, safety, feed tolerance, incidence of infection, and infant growth. Additionally, future research should be sufficiently powered to evaluate the effect of the intervention in infants of different gestational ages, on each sex separately, and on the optimal frequency and duration of exposure.

Early influencing factors on the development of sensory and food preferences

PURPOSE OF REVIEW

The current review focuses on studies investigating the factors related to the development of preferences for foods and sensory inputs (tastes, odours, and food textures) in the first years of life, which constitutes a specific window for food learning.

RECENT FINDINGS

Foetal nutrition, intrauterine growth, and prematurity influence food preferences; this topic warrants more research to broaden our understanding of the 1000 days phenomenon. Although it is less studied than other sensory inputs, food texture acceptance, and the related sensitive period for texture introduction are attracting more attention, as is the impact of fat acceptance. Research should focus not on vegetables alone but on diverse foods whose consumption is encouraged (e.g., fishes and legumes). The role of parental feeding practices, as another major determinant, continues to inspire research exploring the bidirectional influences between children and caregivers. New interventions have confirmed the strong positive influence of repeated exposure to foods through familiarization via taste lessons, cooking, or play activities on acceptance. Interventions that consider individuals traits are necessary.

SUMMARY

Although new evidence is available, it remains a challenge to consider both individual traits and bidirectional influences between parents and children and to investigate this issue worldwide and in all socioeconomic status groups.

Nutritional management of moderate-late preterm infants: Survey of current practice

AIM

Moderate-late preterm (MLPT) babies account for over 80% of preterm babies born world-wide. Many MLPT babies require early nutritional support while full sucking feeds are established, but there is little evidence to guide practice. We aimed to determine current practice in Australia and New Zealand.

METHODS

An electronic survey was sent to neonatal clinical directors within the Australia and New Zealand Neonatal Network requesting dissemination to colleagues involved in the care of MLPT babies (32-35⁺⁶ weeks' gestation). The questionnaire asked about respondents' nutritional management of MLPT babies and included scenarios for both moderate- (MPT) and late preterm (LPT) babies.

RESULTS

There were 83 respondents. While waiting for mothers' milk to meet prescribed fluid volumes, 61% (MPT) to 53% (LPT) of respondents would provide dextrose 10% as the first nutritional support, with 15% (MPT) to 38% (LPT) providing infant formula. Of clinicians providing 10% dextrose, 31% (MPT) to 49% (LPT) were happy to do so for ≥3 days, with 5% comfortable doing so for 5 days in moderately preterm babies, before providing additional support. This additional support was infant formula in 73% (MPT) to 90% (LPT) of respondents.

CONCLUSIONS

There is variation in the nutritional management of MLPT infants amongst neonatal clinicians, likely due to the lack of evidence from randomised controlled trials on which to base clinical practice. The majority of clinicians are happy providing only dextrose 10% for up to 2-3 days despite this form of nutritional support containing only carbohydrate.

Nutritional policies for late preterm and early term infants - can we do better?

Late preterm (LP) and early term (ET) infants can be considered the "great dissemblers": they resemble healthy full-term infants in appearance, but their immaturity places them at increased risk of poor short- and long-term outcomes. Nutritional requirements are greater than for full-term babies, but there are few good data on the nutritional requirements for LP and ET babies, leading to substantial variation in practice. Recent data indicate that rapid growth may be beneficial for neurocognitive function but not for body composition and later metabolic health. Breastfeeding the LP or ET infant can be challenging, and mothers of these infants may need additional support to breastfeed successfully. Future research should investigate nutritional requirements of LP and ET infants for optimal growth, addressing both short- and long-term outcomes and the potential trade-off between neurocognitive and metabolic benefits.

FMRI correlates of olfactory processing in typically-developing school-aged children

Human olfactory processing is understudied relative to other sensory modalities, despite its links to neurodevelopmental and neurodegenerative disorders. To address this limitation, we developed a fast, robust fMRI odor paradigm that is appropriate for all ages and levels of cognitive functioning. To test this approach, thirty-four typically developing children aged 7-12 underwent fMRI during brief, repeated exposure to phenylethyl alcohol, a flower-scented odor. Prior to fMRI scanning, olfactory testing (odor detection and identification) was conducted. During fMRI stimulus presentation, odorant release was synchronized to each participant's inspiratory phase to ensure participants were inhaling during the odorant exposure. Between group differences and correlations between activation and odor detection threshold scores were tested using the FMRIB Software Library. Results demonstrated that our 2-min paradigm significantly activated primary and secondary olfactory regions. In addition, a significant relationship between odor detection threshold and higher activation in the right amygdala and lower activation in the left frontal, insular, occipital, and cerebellar regions was observed, suggesting that this approach is sensitive to individual differences in olfactory processing. These findings demonstrate the feasibility of studying olfactory function in children using brain imaging techniques.