Shaul Dollberg

Sleep and physical growth in infants during the first 6 months

The aim of this study was to explore the relationships between infant sleep patterns and infant physical growth (weight for length ratio) using both objective and subjective sleep measures. Ninety‐six first‐born, healthy 6‐month‐old infants and their parents participated in the study. Infant sleep was assessed by actigraphy for four consecutive nights and by the Brief Infant Sleep Questionnaire (BISQ). In addition, parents were asked to complete background and developmental questionnaires. Questions about feeding methods were included in the developmental questionnaire. Infants’ weight and length were assessed during a standard checkup at the infant‐care clinic when the infants were 6 months old. Significant correlations were found between infant sleep and growth after controlling for potential infant and family confounding factors. Actigraphic sleep percentage and reported sleep duration were correlated negatively with the weight‐to‐length ratio measures. Sex‐related differences in the associations between sleep and physical growth were found. Breast feeding at night was correlated with a more fragmented sleep, but not with physical growth. These findings suggest that sleep is related significantly to physical growth as early as in the first months of life. The study supports increasing evidence from recent studies demonstrating a link between short sleep duration and weight gain and obesity in young children.

Effect of Music by Mozart on Energy Expenditure in Growing Preterm Infants

OBJECTIVE: The rate of weight gain in preterm infants who are exposed to music seems to improve. A potential mechanism could be increased metabolic efficiency; therefore, we conducted this study to test the hypothesis that music by Mozart reduces resting energy expenditure (REE) in growing healthy preterm infants. DESIGN. A prospective, randomized clinical trial with crossover was conducted in 20 healthy, appropriate-weight-for-gestational-age, gavage-fed preterm infants. Infants were randomly assigned to be exposed to a 30-minute period of Mozart music or no music on 2 consecutive days. Metabolic measurements were performed by indirect calorimetry. RESULTS: REE was similar during the first 10-minute period of both randomization groups. During the next 10-minute period, infants who were exposed to music had a significantly lower REE than when not exposed to music (P = .028). This was also true during the third 10-minute period (P = .03). Thus, on average, the effect size of music on REE is a reduction of ∼10% to 13% from baseline, an effect obtained within 10 to 30 minutes. CONCLUSIONS: Exposure to Mozart music significantly lowers REE in healthy preterm infants. We speculate that this effect of music on REE might explain, in part, the improved weight gain that results from this “Mozart effect.”

Fat and Energy Contents of Expressed Human Breast Milk in Prolonged Lactation

Objective. To estimate fat and energy contents of human milk during prolonged lactation. Methods. Thirty-four mothers, of term, healthy, growing children, who had been lactating for >1 year (12–39 months) were recruited. Control subjects were 27 mothers, of term infants, who had been lactating for 2 to 6 months. Fat contents of the milk samples were estimated as creamatocrit (CMT) levels. Energy contents of the milk were measured with a bomb calorimeter. Results. The groups did not differ in terms of maternal height and diet, infant birth weight, gestational age, or breastfeeding frequency. They differed significantly in terms of maternal age, maternal weight, and BMI. The mean CMT levels were 7.36 ± 2.65% in the short-duration group and 10.65 ± 5.07% in the long-lactation group. The mean energy contents were 3103.7 ± 863.2 kJ/L in the short-duration group and 3683.2 ± 1032.2 kJ/L in the long-duration group. The mean CMT levels and mean energy contents were correlated significantly with the duration of lactation (R2 = 0.22 and R2 = 0.23, respectively). In multivariate regression analysis, CMT levels (or energy contents) were not influenced by maternal age, diet, BMI, or number of daily feedings but remained significantly influenced by the duration of lactation. Conclusions. Human milk expressed by mothers who have been lactating for >1 year has significantly increased fat and energy contents, compared with milk expressed by women who have been lactating for shorter periods. During prolonged lactation, the fat energy contribution of breast milk to the infant diet might be significant.

A comparison of intakes of breast-fed and bottle-fed infants during the first two days of life.

Objective: In the first days of life, breast-fed infants consume minimal amounts of milk; this may be explained by substrate limitation (limited milk output) and/or by self-limitation (through low appetite and/or suck-swallow competency). The spontaneous milk intake of unrestricted formula-fed infants has not been studied to date. We compared the spontaneous formula intake of unrestricted formula-fed infants to that of breast-fed infants over the first 48 hours of life. We hypothesized that 1) spontaneous formula intake of unrestricted infants is much higher than that of breast-fed infants and 2) spontaneous formula intake correlates positively with gestational age or birthweight. Methods: We studied 43 healthy, term infants. By maternal choice, 15 infants were exclusively breast-fed and 28 were formula-fed ad libitum every four hours. Breast-fed infants were weighed before and one hour after initiation of feeding, and intake was calculated from the difference between the measurements and corrected individually for the infant’s normal postnatal decrease in body weight. Bottles offered to formula-fed infants contained 60 cc, and the remainder was carefully measured. Intakes were expressed as cc/kg/d, and weight changes as % of birthweight. Statistical methods included Student’s t tests and stepwise regression analysis. Results: Breast feeding on Day 1 was 9.6±10.3 (mean±SD) vs. 18.5±9.6 cc/kg/d in formula-fed infants (p=0.011); on Day 2 it was 13.0±11.3 vs. 42.2±14.2 cc/kg/d (p<0.001). Breast-fed infants lost significantly more weight on Day 2 (p=0.015). In multiple regression, when the dependent variable was the second-day intake, the significant independent variables were group (higher intake in the formula-fed group), weight loss (the higher the weight loss, the lower the intake), and first-day intake (the higher the first-day intake, the higher the second-day intake). Conclusion: Newborn infants offered formula ad libitum every four hours consumed much larger amounts than breast-fed infants fed according to the same schedule. In addition, weight loss was more marked in breast-fed infants on Day 2 of life.

Bone Ultrasound Velocity Curves of Newly Born Term and Preterm Infants

BACKGROUND Ultrasound velocity (speed-of-sound [SOS]) has been proposed as a non-invasive method of evaluation of bone status in infants. We hypothesized that SOS correlates with both gestational age and birth weight. METHODS We measured SOS within the first 96 hours of life at the right tibial midshaft location in 73 neonates ranging in gestational age from 25 to 41 weeks, and in birth weight from 825 to 3880 grams. We used the Sunlight Omnisense 7000p device (Tel Aviv, Israel). Results are expressed as meanS +/- 1 SD; statistical analyses included linear regression and computation of 95% CI regression lines; p<0.05 was considered significant. RESULTS There was, as hypothesized, a significant correlation between gestational age (or birth weight) and SOS. There were no significant differences between males and females. Ninety-five percent confidence intervals were established. CONCLUSIONS These data may be used as reference ranges for further studies.

Feeding Tolerance in Preterm Infants: Randomized Trial of Bolus and Continuous Feeding

Objective: To test the hypothesis that continuous gastric infusion (CGI) is better tolerated than intermittent gastric bolus (IGB) in small very low birth weight (VLBW) infants. Design: Two-center, prospective, randomized, unmasked clinical trial. Patients: 28 VLBW infants (birth weight <1250 g). A strict feeding protocol was followed. Intervention: Patients were randomized to IGB or CGI. Main outcome measures: Time to reach full feeds (160 cc/kg/d)(by design and real), daily weight, caloric intake, residual gastric volume and type of feeding (formula vs. human milk vs. both). Results: Five infants failed to complete the study because of death (n = 4) or protocol violation (n = 1). The two groups did not differ by birth weight or gestational age; infants fed via IGB reached full feeds earlier (p = 0.03) and had less delay in reaching full feeds than infants fed via CGI. Conclusion: Contrary to our hypothesis, gravity IGB is more effective than CGI in improving feeding tolerance in small VLBW infants.

Nucleated red blood cells in infants of smoking mothers.

OBJECTIVE To evaluate whether the absolute nucleated red blood cell (RBC) count is elevated in term, appropriate for gestational age (AGA) infants born to smoking women. METHODS We compared absolute nucleated RBC counts taken during the first 12 hours of life in two groups of term, vaginally delivered, AGA infants, one group born to mothers who smoked during pregnancy (n = 30) and the other born to mothers who did not smoke (n = 30). We excluded infants of women with diabetes, hypertension, or alcohol or drug abuse, and infants with heart rate abnormalities, hemolysis, blood loss, or chromosomal anomalies. RESULTS There were no differences between the groups in birth weight, gestational age, maternal age, gravidity, parity, maternal analgesia during labor, 1- and 5-minute Apgar scores, corrected white blood cell counts, lymphocyte counts, or hematocrits. The median absolute nucleated RBC count in infants of smoking mothers was 0.5 x 10(9)/L (range 0 to 5.0) versus 0.0005 x 10(9)/L (range 0 to 0.6) in nonsmoking controls (P < .002). Regression analysis that included Apgar scores, gestational age, and number of cigarettes smoked per day showed a significant correlation of absolute nucleated RBC count only with the number of cigarettes smoked per day (P < .001). CONCLUSION At birth, term AGA infants born to smoking mothers have increased circulating absolute nucleated RBC counts compared with controls. The absolute nucleated RBC count in newborns correlates with the number of cigarettes smoked during pregnancy.

Circadian variations in fat content of expressed breast milk from mothers of preterm infants.

Background:Little is known about circadian variations of the fat content in expressed human milk by mothers of preterm infants. Objective: To test the hypothesis that the fat content of expressed preterm human milk is higher in samples expressed in the evening (i.e. after 3 daily meals) than in the morning (after a night-long fast). Methods: We collected samples of expressed human milk obtained from 39 mothers of hospitalized growing preterm infants aged 7–14 days, with a gestational age at birth ranging from 26 to 33 weeks, who routinely expressed all their milk every 3 hours, during the day time, just before bed time, and as soon as they woke up, using a commercial breast pump (Medela AG, Baar, Switzerland). One sample was obtained from the first morning expression (between 0600 and 0900) and the second from the evening expression (between 2100 and 2400). The entire quantity of expressed milk was collected, mixed and measured in a capillary tube after centrifugation at 9000 rpm for 5 minutes. Creamatocrits (CMT) were performed in duplicates. Each sample was read independently by 2 investigators who were not aware of the origin and time of sampling and the results were averaged. Results are expressed as mean ± SD, and analyses were by paired t-test and regression analysis. Results: CMT was significantly higher in evening than in morning samples (7.9 ± 2.9% vs. 6.6 ± 2.8%, P = 0.005). Neither CMT nor the morning-evening difference in CMT correlated with gestational age or birthweight. The morning CMT correlated significantly with the evening CMT (P < 0.001). Conclusions: There are significant circadian variations in the CMT of expressed preterm human milk. We speculate that if higher caloric content of expressed human milk is needed in a specific preterm infant, evening sample, if available, should be used preferentially.

Biomechanics of milk extraction during breast-feeding.

Significance We have resolved a century-long scientific controversy and demonstrated with a 3D biophysical model that infants suck breast milk by subatmospheric pressures and not by mouthing the nipple–areola complex to induce a peristaltic-like extraction mechanism. Analysis of ultrasound (US) movies demonstrated that the anterior tongue, which is wedged between the nipple–areola complex and the lower lips, moves as a rigid body with the cycling motion of the mandible, while the posterior section of the tongue undulates like a peristaltic wave, which is essential for swallowing. The computational simulations of breast-feeding successfully mimicked the dynamic characteristics observed in US imaging and also predicted the subatmospheric pressure required to draw the nipple–areola complex into the infant mouth during latch-on. How do infants extract milk during breast-feeding? We have resolved a century-long scientific controversy, whether it is sucking of the milk by subatmospheric pressure or mouthing of the nipple–areola complex to induce a peristaltic-like extraction mechanism. Breast-feeding is a dynamic process, which requires coupling between periodic motions of the infant’s jaws, undulation of the tongue, and the breast milk ejection reflex. The physical mechanisms executed by the infant have been intriguing topics. We used an objective and dynamic analysis of ultrasound (US) movie clips acquired during breast-feeding to explore the tongue dynamic characteristics. Then, we developed a new 3D biophysical model of the breast and lactiferous tubes that enables the mimicking of dynamic characteristics observed in US imaging during breast-feeding, and thereby, exploration of the biomechanical aspects of breast-feeding. We have shown, for the first time to our knowledge, that latch-on to draw the nipple–areola complex into the infant mouth, as well as milk extraction during breast-feeding, require development of time-varying subatmospheric pressures within the infant’s oral cavity. Analysis of the US movies clearly demonstrated that tongue motility during breast-feeding was fairly periodic. The anterior tongue, which is wedged between the nipple–areola complex and the lower lips, moves as a rigid body with the cycling motion of the mandible, while the posterior section of the tongue undulates in a pattern similar to a propagating peristaltic wave, which is essential for swallowing.

Nucleated red blood cells in healthy infants of women with gestational diabetes.

Objective To evaluate whether absolute nucleated red blood cell (RBC) counts are elevated in large-for-gestational-age (LGA) infants of women with gestational diabetes compared with appropriate-for-gestational-age (AGA) infants of women with or without gestational diabetes. Methods We compared absolute nucleated RBC counts during the first 12 hours of life in three groups of term, vaginally delivered infants, LGA infants of women with gestational diabetes (n = 20), AGA infants of women with gestational diabetes (n = 20), and AGA infants of nondiabetic women (n = 30). We excluded infants of women with hypertension, smoking, alcohol or drug abuse, and those with fetal heart rate abnormalities in labor, low Apgar scores, hemolysis, blood loss, or chromosomal anomalies. Results There were no significant differences among groups in gestational age, gravidity, parity, maternal analgesia, 1- and 5-minute Apgar scores, and lymphocyte counts. Corrected white blood cell counts and hematocrit were significantly higher in LGA infants of women with gestational diabetes than in the other groups. The median nucleated RBC count was significantly higher in LGA infants of women with gestational diabetes (0.56 × 109/L, range 0–1.8 × 109/L) than AGA infants of women with gestational diabetes (0.13 × 109/L, range 0–0.65 × 109/L) and controls (0.0005 × 109/L, range 0–0.6 × 109/L) (P < .001). Multiple regression analysis showed that absolute nucleated RBC count was significantly correlated with birth weight (or macrosomia) and maternal diabetic status (r2 = .25, P < .001 for the multiple regression, contribution of birth weight r2 = .19, and diabetes r2 = .06). Conclusion At birth, term LGA infants born to women with gestational diabetes had higher absolute nucleated RBC counts compared with AGA infants born to women with gestational diabetes and controls.