Optimum feeding and growth in preterm neonates

Effects on Growth of Smell and Taste of Milk During Tube Feeding of Preterm Infants: A Randomized Clinical Trial

IMPORTANCE

Smell and taste of food increase food anticipation, activate gut motility, and stimulate digestion and metabolism. Despite poor growth of many preterm infants in neonatal intensive care units, the smell and taste of milk with tube feeding are not generally considered a regular component of care.

OBJECTIVE

To determine the effect of smell and taste of milk with tube feeding on weight z scores at discharge from the hospital.

DESIGN, SETTING, AND PARTICIPANTS

A randomized, controlled, nonblinded, superiority trial was conducted at 2 perinatal centers between May 9, 2017, and February 1, 2020. Eligible infants (n = 659) were born at less than 29 weeks' postmenstrual age (PMA) and/or with a birth weight of less than 1250 g.

INTERVENTIONS

Infants were randomly assigned to receive either the smell and taste of milk with each tube feeding or routine care without the provision of smell and taste of milk.

MAIN OUTCOMES AND MEASURES

The primary outcome was weight z score at discharge from any hospital. Secondary outcomes included anthropometric measures at predefined time points, time to full enteral feeds, and other health outcomes associated with prematurity.

RESULTS

Of the 658 infants, a total of 396 infants were randomized; some parents had not been approached for consent (n = 144) or declined participation (n = 117), and 1 infant with consent was not randomized. Of the 396 infants, 196 were assigned to the treatment group (51% male; mean [SD] PMA at birth, 27.5 [2.2] weeks) and 200 were assigned to the control group (52% male; mean [SD] PMA at birth, 27.6 (2.3) weeks). Mean weight z scores at discharge were -0.87 (95% CI, -1.02 to -0.72) for the treatment group and -0.97 (95% CI, -1.11 to -0.83) for the control group (P = .40). The mean difference in z scores between the treatment and control groups at 36 weeks' PMA was 0.21 (95% CI, 0.01 to 0.4; P = .04) for head circumference and 0.26 (95% CI, 0.05 to 0.51; P = .04) for length. There were no clinically notable differences between the study groups for any other anthropometric, feeding, or health outcomes.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, regular smell and taste of milk included with tube feeding did not improve weight at discharge in preterm infants. Secondary outcomes suggest exposure to smell and taste may improve head circumference and length at 36 weeks' PMA, but not at discharge. Regular exposure to the smell and taste of milk is a simple and inexpensive intervention with potential benefits and no apparent adverse effects.

TRIAL REGISTRATION

anzctr.org.au Identifier: ACTRN12617000583347.

Differential regulation of mTORC1 activation by leucine and β-hydroxy-β-methylbutyrate in skeletal muscle of neonatal pigs

Leucine (Leu) and its metabolite β-hydroxy-β-methylbutyrate (HMB) stimulate mechanistic target of rapamycin (mTOR) complex 1 (mTORC1)-dependent protein synthesis in the skeletal muscle of neonatal pigs. This study aimed to determine whether HMB and Leu utilize common nutrient-sensing mechanisms to activate mTORC1. In study 1, neonatal pigs were fed one of five diets for 24 h: low protein (LP), high protein (HP), or LP supplemented with 4 (LP+HMB4), 40 (LP+HMB40), or 80 (LP+HMB80) μmol HMB·kg body wt^-1·day^-1. In study 2, neonatal pigs were fed for 24 h: LP, LP supplemented with Leu (LP+Leu), or HP diets delivering 9, 18, and 18 mmol Leu·kg body wt^-1·day^-1, respectively. The upstream signaling molecules that regulate mTORC1 activity were analyzed. mTOR phosphorylation on Ser2448 and Ser2481 was greater in LP+HMB40, LP+HMB80, and LP+Leu than in LP and greater in HP than in HMB-supplemented groups (P < 0.05), whereas HP and LP+Leu were similar. Rheb-mTOR complex formation was lower in LP than in HP (P < 0.05), with no enhancement by HMB or Leu supplementation. The Sestrin2-GATOR2 complex was more abundant in LP than in HP and was reduced by Leu (P < 0.05) but not HMB supplementation. RagA-mTOR and RagC-mTOR complexes were higher in LP+Leu and HP than in LP and HMB groups (P < 0.05). There were no treatment differences in RagB-SH3BP4, Vps34-LRS, and RagD-LRS complex abundances. Phosphorylation of Erk1/2 and TSC2, but not AMPK, was lower in LP than HP (P < 0.05) and unaffected by HMB or Leu supplementation. Our results demonstrate that HMB stimulates mTORC1 activation in neonatal muscle independent of the leucine-sensing pathway mediated by Sestrin2 and the Rag proteins.NEW & NOTEWORTHY Dietary supplementation with either leucine or its metabolite β-hydroxy-β-methylbutyrate (HMB) stimulates protein synthesis in skeletal muscle of the neonatal pig. Our results demonstrate that both leucine and HMB stimulate mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) phosphorylation in neonatal muscle. This leucine-stimulated process involves dissociation of the Sestrin2-GATOR2 complex and increased binding of Rag A/C to mTOR. However, HMB's activation of mTORC1 is independent of this leucine-sensing pathway.

Identification of the optimal growth charts for use in a preterm population: An Australian state-wide retrospective cohort study

BACKGROUND

Preterm infants are a group at high risk of having experienced placental insufficiency. It is unclear which growth charts perform best in identifying infants at increased risk of stillbirth and other adverse perinatal outcomes. We compared 2 birthweight charts (population centiles and INTERGROWTH-21st birthweight centiles) and 3 fetal growth charts (INTERGROWTH-21st fetal growth charts, World Health Organization fetal growth charts, and Gestation Related Optimal Weight [GROW] customised growth charts) to identify which chart performed best in identifying infants at increased risk of adverse perinatal outcome in a preterm population.

METHODS AND FINDINGS

We conducted a retrospective cohort study of all preterm infants born at 24.0 to 36.9 weeks gestation in Victoria, Australia, from 2005 to 2015 (28,968 records available for analysis). All above growth charts were applied to the population. Proportions classified as <5th centile and <10th centile by each chart were compared, as were proportions of stillborn infants considered small for gestational age (SGA, <10th centile) by each chart. We then compared the relative performance of non-overlapping SGA cohorts by each chart to our low-risk reference population (infants born appropriate size for gestational age [>10th and <90th centile] by all intrauterine charts [AGAall]) for the following perinatal outcomes: stillbirth, perinatal mortality (stillbirth or neonatal death), Apgar <4 or <7 at 5 minutes, neonatal intensive care unit admissions, suspicion of poor fetal growth leading to expedited delivery, and cesarean section. All intrauterine charts classified a greater proportion of infants as <5th or <10th centile than birthweight charts. The magnitude of the difference between birthweight and fetal charts was greater at more preterm gestations. Of the fetal charts, GROW customised charts classified the greatest number of infants as SGA (22.3%) and the greatest number of stillborn infants as SGA (57%). INTERGROWTH classified almost no additional infants as SGA that were not already considered SGA on GROW or WHO charts; however, those infants classified as SGA by INTERGROWTH had the greatest risk of both stillbirth and total perinatal mortality. GROW customised charts classified a larger proportion of infants as SGA, and these infants were still at increased risk of mortality and adverse perinatal outcomes compared to the AGAall population. Consistent with similar studies in this field, our study was limited in comparing growth charts by the degree of overlap, with many infants classified as SGA by multiple charts. We attempted to overcome this by examining and comparing sub-populations classified as SGA by only 1 growth chart.

CONCLUSIONS

In this study, fetal charts classified greater proportions of preterm and stillborn infants as SGA, which more accurately reflected true fetal growth restriction. Of the intrauterine charts, INTERGROWTH classified the smallest number of preterm infants as SGA, although it identified a particularly high-risk cohort, and GROW customised charts classified the greatest number at increased risk of perinatal mortality.

The effect of smell and taste of milk during tube feeding of preterm infants (the Taste trial): a protocol for a randomised controlled trial

INTRODUCTION

Smell and taste of milk are not generally considered when tube feeding preterm infants. Preterm infants have rapid growth, particularly of the brain, and high caloric needs. Enteral feeding is often poorly tolerated which may lead to growth failure and long-term neurodevelopmental impairment. Smell and taste are strong stimulators of digestion and metabolism. We hypothesise that regular smell and taste during tube feeding will improve weight z-scores of very preterm infants at discharge from hospital.

METHODS AND ANALYSIS

Taste is a randomised, unblinded two-centre trial. Infants born at <29 weeks' gestation and/or <1250 g at birth and admitted to a participating neonatal intensive care unit are eligible. Randomisation occurs before infants receive two hourly feeds for 24 hours. Infants are randomised to either smell and taste of milk with each tube feed or tube feeding without the provision of smell and taste. The primary outcome is weight z-score at discharge. Secondary outcomes include: days to full enteral feeds, duration of parenteral nutrition, rate of late-onset sepsis, post menstrual age at removal of nasogastric tube and at discharge from hospital, anthropometric data and neurodevelopmental outcomes at 2 years of corrected age.

ETHICS AND DISSEMINATION

Human Research Ethics Committees of Mater Misericordiae (trial reference number: HREC/16/MHS/112) and the Royal Women's Hospital (trial reference number: 17/21) last approved the trial protocol (version 4.2; Date: 18 December 2018) and recruitment commenced in May 2017 and November 2017, respectively. The trial results will be published in a peer-reviewed journal and will be presented at national and international conferences.

TRIAL REGISTRATION NUMBER

ACTRN12617000583347.

Smell and Taste to Improve Nutrition in Very Preterm Infants: A Randomized Controlled Pilot Trial

BACKGROUND

The perception of smell and taste, though present early in development, is not routinely considered in the care of preterm infants. Smell and taste are known to increase gut motility, insulin secretion, and the release of appetite, digestive and metabolic hormones.

OBJECTIVE

We aimed to investigate the effect of regular smell and taste on the time from birth to full enteral feeds, and the feasibility of the study protocol in very preterm infants.

METHODS

In a randomized controlled trial, infants <29 weeks' postmenstrual age (PA) were assigned to receive either the smell and taste of milk before each feed or to have no exposure to the smell and taste of milk (control).

RESULTS

Infants in the treatment group (n = 28) and control group (n = 23) were born at a mean (SD) PA of 26.7 (1.5) and 27.2 (1.4) weeks, respectively. They reached full enteral feeds at a median (IQR) of 13.5 (10.0-19.0) and 15.5 (11.0-22.0) days, respectively. Survival analysis showed an adjusted hazard ratio of 1.63 (95% confidence interval 0.91-2.91; p = 0.10) for the effect on the time to establish full enteral feeds. Repeated-measures analysis indicated significant group differences in weight z scores at 36 weeks' PA and at discharge in favor of the intervention (p < 0.05).

CONCLUSION

These data indicate that the smell and taste of milk may improve milk tolerance and weight in preterm infants. The role of regular smell and taste in promoting enteral nutrition and growth in preterm infants merits a larger trial powered to detect important outcomes.