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Biomedical subjects

K G Dewey

Publications and source records attributed to K G Dewey.

At least 37 records · Page 2Linked to original sources
PubMed1999

Promoting exclusive breastfeeding for 4-6 months in Honduras: attitudes of mothers and barriers to compliance.

Prospective and retrospective data on maternal attitudes and obstacles to exclusive breastfeeding (EBF) were collected from Honduran mothers of low birthweight (1500-2500 g), term infants who were enrolled in an intervention study to compare infant outcomes in those who were randomly assigned to breastfeed exclusively for either 4 or 6 months. Perceived advantages of EBF were that it was easier, more practical and economical, and resulted in better infant health and growth. Disadvantages included the perceived time demand, concerns that the infant would accept solids less readily, and fears that breast milk alone was insufficient. The majority of study participants said that they would choose to exclusively breastfeed their next infant to 6 months. Although there were many obstacles to EBF, particularly in the first few weeks, women who persevered became enthusiastic proponents of EBF. Messages to promote EBF need to target the entire community, not just mothers, and should focus on addressing common misconceptions and alerting women to potential problems before they occur.

Adult↗
PubMed1999

Weight change during lactation does not alter the concentrations of chlorinated organic contaminants in breast milk of women with low exposure.

The purpose of this longitudinal study was to evaluate whether a loss of body fat during lactation between 4 and 20 wk postpartum increases the concentration of environmental contaminants in breast milk. We examined this relationship in two different cohorts of exclusively breastfeeding women: (1) California women with low exposure to contaminants (n = 10 whose weight was stable [mean change, 0.0 +/- 0.2 kg] and n = 11 who lost weight [mean loss, -4.1 +/- 0.4 kg]) and (2) Hispanic women (n = 30) who had recently immigrated to North Carolina, primarily from Mexico, and were presumed to have a higher prior exposure to contaminants. Breast milk samples were analyzed for hexachlorobenzene (HCB) and DDT and its related products. There was no significant relationship between change in body composition and change in milk contaminant concentrations in either California or North Carolina women. Concentrations of HCB were similar between the California and North Carolina women, but those of DDT and related products were higher in the North Carolina subjects. Results suggest that moderate weight loss in lactating women with low exposure to environmental contaminants does not increase contaminant concentration in breast milk.

Adult↗
PubMed1998

Cross-cultural patterns of growth and nutritional status of breast-fed infants.

Growth patterns and iron status of infants who were breast-fed throughout their first year of life were examined in four populations: 1) a group of high socioeconomic status in California (the DARLING Study), 2) infants of normal birth weight (NBW) but from low-income families in Honduras, 3) low-birth-weight (LBW), full-term infants in Honduras, and 4) infants in Ghana. z Scores were calculated by using both the current National Center for Health Statistics reference data and a pooled data set based on breast-fed infants in six industrialized countries. The NBW infants in Honduras showed rapid growth in the first few months and were similar in weight-for-age to the DARLING infants until approximately 9 mo. By contrast, the LBW infants remained far below the other cohorts throughout the first 12 mo, despite an initial period of catch-up growth. In the Ghanaian infants, weight-for-age faltered beginning at 3-4 mo, but length-for-age did not falter until after 9 mo. Weight-for-length was highest in the NBW Honduran infants and lowest in the Ghanaian infants. When z scores were adjusted for birth weight and maternal height, no significant faltering was evident in either weight or length in any of the cohorts during the first 12 mo. Thus, when breast-feeding is continued during the first year of life and efforts are made to ensure adequate complementary feeding after 6 mo, if growth faltering occurs it is probably attributable to prenatal factors and maternal stature. Population differences in iron status reflected variation in birth weight and in the use of iron-rich foods. Therefore, efforts to prevent child stunting and malnutrition must pay attention to prenatal as well as postnatal factors.

Aging↗
PubMed1998

Effects of age of introduction of complementary foods on iron status of breast-fed infants in Honduras.

To evaluate the effect of introducing complementary foods before 6 mo of age, we randomly assigned 164 infants who had been exclusively breast-fed for 4 mo to continue being exclusively breast-fed until 6 mo (EBF group) or to receive iron-fortified foods in addition to breast milk from 4 to 6 mo (BF+SF group). At 6 mo, the BF+SF group had higher mean iron intake (4 mg/d compared with 0.2 mg/d in EBF infants) and higher hemoglobin, hematocrit, and ferritin values than the EBF group (P < 0.05). The percentage with low hemoglobin (< 103 g/L) did not differ significantly between groups, but fewer infants in the BF+SF group had a low hematocrit (< 0.33; 21.4% compared with 32.0%, respectively; P < 0.05). The percentage of infants with ferritin concentrations < 12 microg/L at 6 mo was lower than the percentage with low hemoglobin or hematocrit, raising questions about the validity of the cutoffs at this age. Infants at greatest risk for anemia and low ferritin were those with birth weights < 2500 g; no infant with a birth weight > 3000 g had a low ferritin value at 6 mo. We conclude that the risk of iron deficiency is low among infants with birth weights > 3000 g who are exclusively breast-fed for 6 mo. Iron drops are recommended for low-birth-weight infants; for breast-fed infants with birth weights between 2500 and 3000 g, further research is needed to determine whether iron drops are more effective than complementary foods for preventing iron deficiency before 6 mo.

Age Factors↗
PubMed1998

Stress during labor and delivery and early lactation performance.

The amount of stress experienced by both the mother and fetus during labor and delivery varies considerably and is likely to be different in primiparous and multiparous women. In this study we explored relations between the birth experience and lactation performance of 40 women. Stress hormones were measured in serum or plasma during pregnancy, parturition (cord and maternal blood), and lactation. Milk samples were obtained and breast-feeding frequency was recorded each day during the first 2 wk postpartum. Four outcomes were used as markers of lactogenesis: the time when the subject first felt fullness in the breasts, 24-h milk volume on day 5 postpartum, milk lactose concentration on day 5, and the day of appearance of casein in the milk as determined by gel electrophoresis. There were significant intercorrelations among the outcome variables, except for milk lactose. Compared with multiparous women, primiparous mothers experienced a delay in breast fullness and lower milk volume on day 5. In multiple regression analyses excluding subjects who had cesarean deliveries (n = 5), markers of both fetal and maternal stress during labor and delivery (cord glucose concentration and maternal exhaustion score) were associated with delayed breast fullness and casein appearance; delayed casein appearance was also associated independently with a longer duration of labor. Milk volume on day 5 was lower in women with higher exhaustion scores, and, in multiparous women, those who breast-fed less frequently on day 2. The milk lactose concentration was inversely related to pregnancy weight gain. These results indicate that primiparity, long labor, stress to the mother and fetus during labor and delivery, and elevated cord glucose concentrations are risk factors for delayed lactogenesis.

Adult↗
PubMed1998

Effects of maternal caloric restriction and exercise during lactation.

In affluent populations, breast-feeding women often wish to return to their prepregnancy weight as soon as possible postpartum and may restrict energy intake or increase exercise to achieve this goal. Gradual weight loss (< or = 2 kg/mo) seems to have no adverse effect on milk volume or composition, provided that the mother is not undernourished and is breast-feeding her infant on demand. Aerobic exercise improves cardiovascular fitness and does not affect milk energy transfer to the infant, but exercise alone is not likely to increase the rate of weight loss unless dietary intake is controlled. Less information is available on the effect of rapid weight loss. Data from a recent randomized intervention trial indicate that a short-term (11 d) energy deficit of 35%, achieved by dieting or a combination of dieting and increased exercise, results in weight loss > 1 kg/wk and does not adversely affect lactation. Exercise enhances maintenance of lean body mass and is therefore a recommended component of any weight loss program. Maternal plasma prolactin concentration generally increases under conditions of negative energy balance, which may serve to protect lactation. Further research is required on the longer-term effect of energy restriction and on the effects of energy balance in lactating women with low fat reserves.

Diet, Reducing↗
PubMed1998

Body composition by air-displacement plethysmography by using predicted and measured thoracic gas volumes.

The BOD POD, a new air-displacement plethysmograph for measuring human body composition, utilizes the inverse relationship between pressure and volume (Boyle's law) to measure body volume directly. The quantity of air in the lungs during tidal breathing, the average thoracic gas volume (Vtg), is also measured by the BOD POD by using a standard plethysmographic technique. Alternatively, the BOD POD provides the use of a predicted Vtg (Vtgpred). The validity of using Vtgpred in place of measured Vtg (Vtgmeas) to determine the percentage of body fat (%BF) was evaluated in 50 subjects (36 women, 14 men; ages 18-56 yr). There was no significant difference between Vtgmeas and Vtgpred (mean difference +/- SE, 53.5 +/- 63.3 ml) nor in %BF by using Vtgmeas vs. Vtgpred (0.2 +/- 0.2 %BF). On an individual basis, %BF measured by using Vtgmeas vs. Vtgpred differed within +/-2.0% BF for 82% of the subjects; maximum differences were -2.9 to +3.0% BF. For comparison, data from 24 subjects who had undergone hydrostatic weighing were evaluated for the validity of using predicted vs. measured residual lung volume (VRpred vs. VRmeas, respectively). Differences between VRmeas and VRpred and in %BF calculated by using VRmeas vs. VRpred were significant (187 +/- 46 ml and 1.4 +/- 0.3% BF, respectively; P < 0.001). On an individual basis, %BF determined by using VRmeas vs. VRpred differed within +/-2.0% BF for 46% of the subjects; maximum differences were -2.9 to +3.8% BF. With respect to %BF measured by air displacement, our findings support the use of Vtgpred for group mean comparisons and for purposes such as screening in young to middle-aged individuals. This contrasts with the use of VRpred in hydrostatic weighing, which leads to significant errors in the estimation of %BF. Furthermore, although the use of Vtgpred has some application, determining Vtgmeas is relatively simple in most cases. Therefore, we recommend that the use of Vtgmeas remain as standard experimental and clinical practice.

Adipose Tissue↗
PubMed1998

Growth characteristics of breast-fed compared to formula-fed infants.

In affluent populations, breast-fed infants generally exhibit a different pattern of growth than formula-fed infants. The average weight gain of the former is lower than that of the latter, even after complementary foods are introduced. In some studies, the length gain is also lower among breast-fed infants, whereas in others there is no significant difference in linear growth between feeding groups. Growth in head circumference does not differ by feeding mode. Because of the difference in weight gain, breast-fed infants are generally leaner than formula-fed infants by 12 months of age. Breast-fed infants appear to self-regulate their energy intake at a lower level than consumed by formula-fed infants and have a lower metabolic rate. Evidence to date suggests that there are no apparent adverse consequences associated with the lower intake and slower weight gain of breast-fed infants: compared to formula-fed infants, they do not differ in activity level, and they experience less illness and appear to have enhanced cognitive development. The reasons for differences in growth patterns by feeding mode require further research.

Adipose Tissue↗
PubMed1998

Growth patterns of breastfed infants and the current status of growth charts for infants.

In summary, numerous studies have indicated that the pattern of growth during infancy is influenced by feeding mode. Compared to formula-fed infants, breastfed infants generally gain less weight, particularly after the first few months of life. This appears to be a normal pattern among healthy, thriving infants. Although true growth faltering can certainly occur among breastfed infants, it is difficult to evaluate using the NCHS growth chart, which is based on a sample of predominantly formula-fed infants. This situation has prompted WHO to begin the process of creating a new growth chart based on breastfed infants.

Anthropometry↗
PubMed1997

Delayed clamping of the umbilical cord improves hematologic status of Guatemalan infants at 2 mo of age.

Iron deficiency anemia is a serious health problem that affects the physical and cognitive development of children. Therefore, it is important to develop cost-effective interventions to improve the hematologic status of the millions of children affected by this condition worldwide. We studied 69 Guatemalan infants who had been randomly assigned to one of three groups at the time of delivery: 1) cord clamping immediately after delivery (n = 21); 2) clamping when the cord stopped pulsating, with the infant placed at the level of the placenta (n = 26); or 3) clamping when the cord stopped pulsating, with the newborn placed below the level of the placenta (n = 22). Maternal and infant hematologic assessments were performed at the time of delivery and 2 mo postpartum. At baseline the groups had similar socioeconomic, demographic, and biomedical characteristics and the newborns had similar hematocrit status. Two months after delivery, infants in the two groups with delayed cord clamping had significantly higher hematocrit values and hemoglobin concentrations than did those in the early-clamping group. The percentage with hematocrit values < 0.33 was 88% in the control group compared with 42% in group 2 and 55% in group 3 (P = 0.01). These results suggest that waiting until the umbilical cord stops pulsating (approximately 1 min after delivery) is a feasible low-cost intervention that can reduce anemia in infants in developing countries.

Adult↗
PubMed1997

Validation of single daytime samples of human milk to estimate the 24-h concentration of lipids in urban Guatemalan mothers.

The large within- and between-sample variability in breast milk lipid content greatly complicates the collection of representative samples in field studies. The main purpose of this study was to validate the ability of individual daytime samples to predict the 24-h lipid concentration of breast milk. We also studied maternal, child, and other factors (time of day and interval between feeds) associated with the within- and between-mother variability in milk lipid content. Fifty-two primiparous urban Guatemalan women between 1 and 4 mo postpartum were studied. Milk samples were collected during six 2-h intervals from 0600 to 1800, and throughout the night when the child breast-fed. On average, the 24-h pooled milk samples contained 4.2 +/- 0.92% (mean +/- SD) lipids and the best concordance with this value was obtained with samples collected between 0600 and 0800 (concordance correlation coefficient = 0.60, P < 0.05). None of the regression equations to predict the 24-h lipid content of breast milk based on daytime samples reached a sufficiently high predictive power to be recommended for the estimation of individual child intake. Time of day and time elapsed since the last feeding were significant determinants of diurnal variations in milk lipid content, whereas between-mother variability was explained by maternal weight (P = 0.05) and body mass index (P < 0.05). For the collection of milk samples in surveys and pre-post studies, we recommend standardization of time of day and interval between feeds.

Adult↗
PubMed1997

Effects of age at introduction of complementary foods to breast-fed infants on duration of lactational amenorrhea in Honduran women.

Lactational amenorrhea (LA) is associated with postpartum infertility and is known to be related to breast-feeding frequency and duration, but the exact role of complementary feeding of the infant has not been clearly defined. Data on LA were collected during and after a 2-mo intervention trial in which low-income Honduran women who had breast-fed fully for 4 mo were randomly assigned to one of three groups: continued full breast-feeding until 6 mo (FBF, n = 50), introduction of complementary foods at 4 mo with ad libitum breast-feeding from 4 to 6 mo (SF, n = 47), or introduction of complementary foods at 4 mo with maintenance of baseline breast-feeding frequency from 4 to 6 mo (SF-M, n = 44). Women were followed up until the infant was 12 mo of age, or later if menses had not occurred by then. All but six of the women continued to breast-feed for > or = 12 mo. With the exclusion of those whose menses returned before 18 wk postpartum (which could not have been due to the intervention), the proportion of women who were amenorrheic at 6 mo was 64.5% in the SF group, 80.0% in the FBF group, and 85.7% in the SF-M group (chi-square test = 4.13, P = 0.02; one-tailed test with the latter two groups combined). The total duration of LA did not differ significantly among groups. The most significant determinant of LA was time spent breast-feeding (min/d), which was in turn negatively associated (P = 0.06) with the infant's energy intake from complementary foods in regression analyses. These results indicate that there is a significant effect of introducing foods at 4 mo on the likelihood of amenorrhea at 6 mo postpartum, but not thereafter, and that this effect is not seen in mothers who maintain breast-feeding frequency.

Adolescent↗
PubMed1997

Effects of discontinuing coffee intake on iron status of iron-deficient Guatemalan toddlers: a randomized intervention study.

Coffee is one of the first liquids given to infants in Guatemala. To evaluate whether this practice has an adverse effect on iron status, 160 children 12-24 mo of age who had received coffee for > or = 2 mo and had at least one indicator of iron deficiency were stratified by initial hemoglobin concentration (anemic, or nonanemic, ie, hemoglobin > or = 105 g/L) and randomly assigned to a control (continuation of coffee; coffee) or intervention (provided with a substitute consisting of sugar and coloring; substitute) group for 5 mo. Anemic children were provided with iron supplements for 2-3 mo. Hematologic and anthropometric measurements were made before and after the intervention and dietary and morbidity data were collected every 2 wk. A total of 139 children completed the study: 45 coffee, nonanemic; 56 substitute, nonanemic; 19 coffee, anemic; and 19 substitute, anemic. Compliance with the procedures was good: median coffee intake was 891 mL/wk in the coffee group compared with 18 mL/wk in the substitute group (P = 0.0001). There was no significant effect of discontinuing coffee consumption on changes in hemoglobin, hematocrit, ratio of zinc protoporphyrin to heme or plasma iron, zinc or copper in either nonanemic or anemic children, or plasma ferritin in children who did not take iron supplements. In children who took iron supplements, change in plasma ferritin was significantly greater in the substitute group than in the coffee group (106% compared with 1%, P < 0.05). This implies that coffee interferes with the utilization of supplemental iron. It is likely that the amount and strength of coffee consumed by Guatemalan toddlers are too low to significantly affect the other indexes of iron status.

Anemia↗
PubMed1997

Between-day and within-day variability in the relation between heart rate and oxygen consumption: effect on the estimation of energy expenditure by heart-rate monitoring.

Estimation of energy expenditure (EE) by heart-rate (HR) monitoring (HRM) assumes that the relation between HR and oxygen consumption (VO2) is stable between days and within a day. To evaluate this assumption, 12 healthy subjects underwent an HR-VO2 calibration session on two mornings and two afternoons, with one morning and one afternoon session on the same day. Measurements were made while subjects were supine, sitting, standing while shifting body weight side-to-side, and walking at four intensities. Subjects wore an HR monitor during waking hours on another day (15.1 +/- 1.5 h). Regression analysis was used to determine the relation between HR and VO2 in the sedentary and active HR ranges, and four EE values (HRM-EE) based on the four calibration sessions were calculated for each subject. The four group mean HRM-EE values were nearly identical (CV: 1.1%). The regression equations generated from the four calibration sessions did not differ significantly for the group as a whole, but for some subjects there were significant differences among sessions in the slope of the active regression equation (P = 0.005). Intraindividual CVs for HRM-EE were generally < 10%, but ranged from 0.1% to 24.7%. In general, within an individual, HR was more variable than was VO2, and intraindividual variability in EE was associated with intraindividual variability in the flex HR and sedentary HR range. HRM is appropriate for assessment of EE for a group; however, caution is recommended when HRM is used for individual determinations of EE.

Adult↗
PubMed1997

A randomized intervention study of the effects of discontinuing coffee intake on growth and morbidity of iron-deficient Guatemalan toddlers.

Coffee is widely consumed by children in Guatemala. To evaluate whether coffee has an adverse effect on growth or morbidity, 160 children 12-24 mo of age who had received coffee for > or = 2 mo and had at least one indicator of iron deficiency were stratified by initial hemoglobin (Hb) (A = anemic vs. NA = "nonanemic", i.e., Hb > or = 105 g/L) and randomly assigned to a control (C = continuation of coffee) or intervention group (S = provided with a substitute consisting of sugar and coloring) for 5 mo. Anemic children were provided iron supplements for 2-3 mo. Hematological and anthropometric measurements were made before and after the intervention, and dietary and morbidity data were collected every 2 wk. A total of 139 children completed the intervention: 45 C-NA, 56 S-NA, 19 C-A and 19 S-A. Compliance with the intervention was good: median coffee intake was 127 mL/d in group C vs. 3 mL/d in group S (P = 0.0001). There were no significant differences between C vs. S groups in food intake before or after the intervention. In the total sample, there was no effect of the intervention on weight or length gain. However, in children initially consuming more than 100 mL/d of coffee (n = 96), length gain was 22% greater in the S vs. the C group (P = 0.07), and weight gain was 46% greater in the S-A vs. the C-A group (P < 0.05; NS in the NA groups). Total illness prevalence (particularly respiratory illness) was significantly lower in the S-NA vs. the C-NA group (P < 0.05), but somewhat higher in the S-A vs. the C-A group (P = 0.09). Morbidity differences did not explain the effect of the intervention on growth. These results indicate a modest increase in growth associated with discontinuation of coffee consumption by toddlers with initial intakes >100 mL/d.

Anemia, Iron-Deficiency↗