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Biomedical subjects

K G Dewey

Publications and source records attributed to K G Dewey.

At least 55 records · Page 3Linked to original sources
PubMed1997

Energy and protein requirements during lactation.

Additional energy needs for an exclusively breastfeeding woman are approximately 670 kcal/day. If one allows for gradual weight loss, the net increment needed is about 500 kcal/day. There is little evidence of energy-sparing adaptations in basal metabolic rate or dietary-induced thermogenesis during lactation, although physical activity may be reduced during the early postpartum period. In women with adequate fat reserves, moderately negative energy balance is not likely to affect lactation. The recommended increment in protein intake during lactation has been estimated to be about 15 g/day, based on a milk protein concentration of 11 g/liter. However, if one takes into account the protein cost of non-protein nitrogen in human milk, the recommended increment in protein is about 20 g/day. The latter value is consistent with data from nitrogen balance studies in lactating women. Low protein intakes are unlikely to affect milk volume but may alter certain fractions of milk nitrogen.

Dietary Proteins↗
PubMed1997

Effects of coffee consumption on iron, zinc and copper status in nonpregnant and pregnant Sprague-Dawley rats.

To investigate the influence of coffee consumption on iron, zinc and copper status, 64 Sprague-Dawley female rats were assigned to four treatment groups: nonpregnant-given coffee, nonpregnant-given water, pregnant-given coffee and pregnant-given water. The coffee groups received a freeze-dried coffee solution (1.1% w/v) as the sole source of liquids during the 18-day study period; all groups were provided a purified diet marginal in iron ad libitum. On day 18 (of gestation in the pregnant rats), rats were intubated with 0.033 MBq59Fe after an 8 h fast and killed 4, 8, 12 or 24 h post-gavage. Fluid intake was significantly lower in the coffee groups. Coffee did not affect food consumption, weight gain, hemoglobin or hematocrit in either pregnant or nonpregnant rats. In nonpregnant rats, the percentage of 59Fe was lower in plasma and higher in the spleen and erythrocytes in the coffee group than in controls; in pregnant rats the coffee group had a higher percentage of 59Fe in the stomach (at 4 h only), blood, spleen and bone than controls. There were no significant effects of coffee on tissue concentrations of Fe, Zn or Cu in the nonpregnant group, but pregnant rats given coffee had high concentrations of Fe in the liver, bone and placenta, and low placenta Zn concentrations compared to controls. In fetuses, there were trends towards lower weight, length and percentage 59Fe, but higher liver Fe, in the coffee group than in the controls. The results suggest that coffee intake leads to (a) increased attempts at erythropoeisis, an indication of iron deficiency, in both nonpregnant and pregnant rats, and (b) impaired placental Fe transport.

Animals↗
PubMed1996

Potential cost savings for Medi-Cal, AFDC, food stamps, and WIC programs associated with increasing breast-feeding among low-income Hmong women in California.

OBJECTIVE: To determine the potential cost savings for four social service programs if breast-feeding rates increased among Hmong women in California. DESIGN: Cost-savings analysis. SUBJECTS/SETTING: Hmong women in California. In this population, breast-feeding is currently uncommon, and use of contraceptives is minimal. MAIN OUTCOME MEASURES: Savings were based on estimates of the resulting decrease in infant morbidity, maternal fertility, and formula purchases (Special Supplemental Nutrition Program for Women, Infants, and Children) if women breast-fed each child for at least 6 months. Costs were projected over a 7.5-year period and future values were discounted with annual interest rates of 2% or 4%. RESULTS: Substantial savings estimates were associated with breast-feeding for all four programs. The total projected savings over the 7.5-year period ranges from $3,442 to $4,944 (4% discount) to $4,475 to $6,0960 (0% discount) per family enrolled in all four programs. This translates into an estimated yearly savings of between $459 and $659 (4% discount) and $597 and $808 (0% discount) per family. APPLICATIONS: Although health care providers generally accept that breast-feeding is the preferred method for feeding infants, many still view the choice as a neutral one; that is, they consider low breast-feeding rates in the United States a cultural choice with no cost to society. This analysis provides evidence that breast-feeding is economically advantageous for individuals and society.

Aid to Families with Dependent Children↗
PubMed1996

Do exclusively breast-fed infants require extra protein?

It has been argued that the growth rate of exclusively breast-fed infants may be limited by their protein intake. This issue was examined using data from an intervention study in Honduras in which infants were randomly assigned to be exclusively breast-fed for the first 6 mo (EBF; n = 50), or to receive preprepared solid foods (including egg yolk) in addition to breast milk beginning at 4 mo (n = 91). Neither weight gain nor length gain from 4 to 6 mo differed between groups despite a 20% higher protein intake (as well as significantly higher intakes of iron, zinc, calcium, vitamin A, and riboflavine) in the latter group. The 20 infants with the highest protein intakes in that group were matched to 20 EBF infants on the basis of energy intake; protein intake was 1.46 +/- 0.09 versus 1.10 +/- 0.17 g/kg/d, respectively (p < 0.001), but growth rate did not differ between groups. Similarly, the 20 infants with the lowest protein intakes in the EBF group were matched (by energy intake) to 20 infants given solid foods; protein intake was very low in the former compared with the latter (0.81 +/- 0.13 versus 1.04 +/- 0.20 g/kg/d; p < 0.001), yet there was still no difference in growth. Infant morbidity was relatively low and did not influence the results. These analyses indicate that protein intake is not likely to be a limiting factor with regard to growth of breast-fed infants from 4 to 6 mo of age.

Body Height↗
PubMed1996

The association between cesarean delivery and breast-feeding outcomes among Mexican women.

OBJECTIVES: This study examined the impact of cesarean section delivery on the initiation and duration of breast-feeding in the 1987 Mexican Demographic and Health Survey. METHODS: The subsample (n = 2517) was restricted to women whose delivery of their last-born children (aged 5 years and younger) was attended by a physician. Multivariate logistic regression was used to examine the association between cesarean section and likelihood of either not initiating breast-feeding or doing so for less than 1 month. Among women who breast-fed for 1 month or more, multivariate survival analysis was used to examine the relationship between cesarean section and breast-feeding duration. RESULTS: Cesarean section was a risk factor for not initiating breast-feeding (odds ratio [OR] = 0.64, 95% confidence interval [CI] = 0.50, 0.82) and for breast feeding for less than 1 month (OR = 0.58, 95% CI = 0.37, 0.91) but was unrelated to breast-feeding duration among women who breast-fed for 1 month or more (OR = 0.97, 95% CI = 0.86, 1.11). CONCLUSIONS: It is desirable to provide additional breast-feeding support during the early postpartum period to women who deliver via cesarean sections.

Adolescent↗
PubMed1995

Maternal activity budgets: feasibility of exclusive breastfeeding for six months among urban women in Honduras.

Although exclusive breastfeeding for 6 months is likely to be beneficial for infant health, mothers often cite time pressures as a reason to introduce other foods. Using 12-hr in-home observations at 19 and 24 wk postpartum, we compared maternal activity budgets and time spent breastfeeding among low-income, urban mothers not employed outside the home who exclusively breastfed (EBF) or gave other foods in addition to breast milk (BF+SF). Breastfeeding time was similar between groups (averaging approx 75 min/12 hr) except that multiparous EBF mothers at 24 wk spent more time breastfeeding their infants than did BF+SF mothers. However, total time devoted to infant feeding (including preparation and feeding of solids in the BF+SF group) was significantly greater in the BF+SF group than in the EBF group (except among multiparous women at 24 wk). Feeding frequency per 12-hr averaged 6.7-8.9 in the EBF group and 5.4-8.1 BF + 1.8 meals in the BF+SF group. Both EBF and BF+SF mothers had considerable 'free' time; they spent, on average, 2-3 hr during each 12-hr period resting, chatting or watching TV. Primiparous women tended to spend less time at household chores and child care than multiparous women. Of the BF+SF mothers, 60% said that breastfeeding was 'somewhat' or 'very' time-demanding (vs 15% of EBF mothers), 49% said that it interfered with other activities (vs 6% of EBF mothers), and 26% said that they gave other foods to extend the time between breastfeeds. Although many of the BF+SF mothers knew that giving foods may increase infant illness, there were cultural pressures not to exclusively breastfeed. For example, many introduced solids to their infants prior to 6 months because they believed that infants should 'learn' how to eat other foods, to 'acclimate' the stomach and learn to differentiate flavors. We conclude that time constraints are not a barrier to exclusive breastfeeding in this population, although they may be perceived as a barrier.

Activities of Daily Living↗
PubMed1995

Differences in morbidity between breast-fed and formula-fed infants.

To determine whether breast-feeding is protective against infection in relatively affluent populations, morbidity data were collected by weekly monitoring during the first 2 years of life from matched cohorts of infants who were either breast fed (BF) (N = 46) or formula fed (FF) (N = 41) until at least 12 months of age. Cohorts were matched for characteristics such as birth weight and parental socioeconomic status, and we controlled for use of day care in data analysis. Mean maternal educational level was high (16 years) in both groups. In the first year of life the incidence of diarrheal illness among BF infants was half that of FF infants; the percentage with any otitis media was 19% lower and with prolonged episodes (> 10 days) was 80% lower in BF compared with FF infants. There were no significant differences in rates of respiratory illness; nearly all cases were mild upper respiratory infections. Morbidity rates did not differ significantly between groups in the second year of life, but the mean duration of episodes of otitis media was longer in FF than BF infants (8.8 +/- 5.3 vs 5.9 +/- 3.5 days, respectively; p = 0.01). These results indicate that the reduction in morbidity associated with breast-feeding is of sufficient magnitude to be of public health significance.

Adult↗
PubMed1995

Maternal anthropometric status and lactation performance in a low-income Honduran population: evidence for the role of infants.

As part of a study on the optimal timing of complementary feeding in Honduras, we assessed breast milk volume and composition at 4, 5, and 6 mo in 141 low-income women who were randomly assigned to exclusively breast-feed for the first 6 mo or to complement breast milk with prepared solid foods beginning at 4 mo. Milk volume averaged 797 +/- 139 g/d at 4 mo. Maternal body mass index was positively associated with infant birth weight and milk energy density. In multivariate analyses in which group assignment was controlled for, milk volume was positively associated with birth weight but negatively associated with milk energy density. Infant breast milk energy intake was positively associated with birth weight and milk energy density. Maternal anthropometric status was not a significant predictor of milk volume or infant energy intake when birth weight and milk energy density were included in the models. These results indicate that infant characteristics, such as birth weight and the ability to self-regulate intake in response to milk energy density, mediate the relationship between maternal anthropometric status and lactation performance.

Anthropometry↗
PubMed1995

Delaying the introduction of complementary food until 6 months does not affect appetite or mother's report of food acceptance of breast-fed infants from 6 to 12 months in a low income, Honduran population.

Low income, primiparous mothers who had exclusively breast-fed for 4 mo were randomly assigned to one of three groups: 1) continued exclusive breast-feeding to 6 mo (EBF), 2) introduction of complementary foods at 4 mo, with ad libitum nursing 4-6 mo (SF), and 3) introduction of complementary foods at 4 mo, with maintenance of base-line nursing frequency 4-6 mo (SF-M). After the intervention phase (4-6 mo; n= 141), home visits were conducted for a subsample at 9 (n = 60) and 12 (n = 123) mo. At each visit, an observer recorded infant food intake at the midday meal and interviewed the mother regarding usual feeding patterns and the infant's acceptance of 20 common food items. All but two infants (1.5%) were breast-fed to 9 mo and all but eight (6%) to 12 mo. There were no significant differences among groups in breast-feeding frequency, amount or number of foods consumed at the midday meal, percentage of food offered that was consumed, usual daily number of meals and snacks, number of food groups consumed, or overall food acceptance score. Frequency of consumption of foods from eight different food groups (dairy, meats, eggs, grains, beans, fruits, vegetables, tubers) was not significantly different among groups except that, at 9 mo only, the SF group (but not the SF-M group) consumed more vegetables than did the EBF group. These results indicate that delaying the introduction of complementary foods until 6 mo does not adversely affect appetite or food acceptance among breast-fed infants.

Adolescent↗
PubMed1995

Infant bottle propping among a low-income urban population in Mexico.

The prevalence of bottle propping (permitting an infant to drink from a bottle unattended) and the determinants of this practice at 1 week and 4 months of life were studied in a selected sample of urban women in Hermosillo, Mexico. The sample (n = 165) consisted of mothers planning to breast-feed who gave birth to healthy infants at one of two public hospitals. Data were obtained by interviewing women shortly before they were discharged from the hospital and at about 1 week and 4 months postpartum. Among those mothers giving liquid breast milk substitutes to their infants, the percentage practicing bottle propping increased from 27% at 1 week (n = 20/74) to 67% at 4 months (n = 87/130). Women who practiced bottle propping at 1 week were significantly more likely to continue this practice at 4 months. Bottle propping was significantly more common, both at 1 week and 4 months, among women who had completely weaned their infants than among those who were still combining breast and formula feeding. Multivariate logistic regression indicated that 1-week risk factors for bottle propping were low socioeconomic status, being a multiparous single mother, and being a young mother (< or = 18 years old) with a female infant, while 4-month risk factors were complete weaning, delivery in a "nursery" (versus a "rooming-in") hospital, and lack of support by the mother's partner for breast-feeding. While the possible health risks associated with early bottle propping have not been well defined, the extent of the practice observed in this study suggests that such risks deserve further investigation.

Adolescent↗
PubMed1995

Growth of breast-fed infants deviates from current reference data: a pooled analysis of US, Canadian, and European data sets. World Health Organization Working Group on Infant Growth.

OBJECTIVE: To compare growth patterns of a large sample of breast-fed infants with the current World Health Organization (WHO)/Centers for Disease Control and Prevention (CDC) reference data. METHODS: Data from seven longitudinal studies of infant growth in North America and northern Europe were pooled (n = 453 breast-fed infants). Weight, length and head circumference were compared with the WHO/CDC reference, and repeated-measures analysis of variance was used to examine associations between growth patterns and breast-feeding duration, age of introduction of solid foods, and use of other milks. RESULTS: In comparison with WHO/CDC reference data, infants breast-fed for at least 12 months (n = 226) grew more rapidly in the first 2 months and less rapidly (particularly in weight) from 3 to 12 months; the mean z score at 12 months was -0.53 for weight for age, -0.29 for length for age, and -0.32 for weight for length. In contrast, mean head circumference was well above the WHO/CDC median throughout the first year of life. These patterns were generally consistent across studies. In the full sample (n = 453), a longer duration of breast-feeding was associated with a greater decline in weight for age and weight for length but not length for age. CONCLUSION: These results suggest that if growth charts are to reflect patterns consistent with those of infants following WHO feeding recommendations, new reference data based on breast-fed infants are needed.

Age Factors↗
PubMed1995

Determinants of growth from birth to 12 months among breast-fed Honduran infants in relation to age of introduction of complementary foods.

OBJECTIVES: To evaluate the impact of introducing complementary foods to exclusively breast-fed infants at 4 vs 6 months on growth from 6 to 12 months, and to compare growth patterns of Honduran infants with those of breast-fed infants in the United States. DESIGN: Randomized intervention trial from 4 to 6 months and longitudinal study of infants from birth to 12 months. SETTING: Low-income communities in San Pedro Sula, Honduras. SUBJECTS: Primiparous, breast-feeding mothers and their infants (n = 141) recruited from public maternity hospitals. INTERVENTION: Infants were randomly assigned to exclusive breast-feeding to 6 months, or exclusive breast-feeding with addition of hygienically prepared, nutritionally adequate complementary foods at 4 months, with or without maintenance of baseline breast-feeding frequency. After 6 months, mothers continued to breast-feed and also fed their infants home-prepared foods after receiving instruction in appropriate feeding practices. OUTCOME MEASURES: Infant weight was measured monthly during the first year of life and infant length monthly from 4 to 12 months. STATISTICAL ANALYSIS: Growth parameters were compared between the Honduran and US cohorts using multiple-regression and repeated-measures analysis of variance. Stepwise multiple regression was used to identify determinants of infant growth. RESULTS: There were no differences in growth patterns by intervention group. Mean birth weight of the Honduran infants was significantly less than that of a cohort of breast-fed infants in an affluent US population (n = 46) (2889 +/- 482 vs 3611 +/- 509 g), but the Honduran infants exhibited rapid catch up in weight in the first few months of life, and the cohorts were similar in weight by 3 months. Mean weight and length gain were similar to those of the US cohort from 4 to 9 months but were lower from 9 to 12 months. Mean length for age was significantly less than that of the US cohort from 4 to 12 months; this was attributable to the difference in maternal height (12 cm shorter in Honduras on average). Within the Honduran cohort, growth velocity of low birth weight infants (< 2500 g; n = 28) was similar to that of their normal birth weight peers; thus, the former subgroup remained smaller than the latter throughout the first year of life. CONCLUSIONS: In poor populations, when breast-feeding is exclusive for the first 4 to 6 months, continues from 6 to 12 months, and is accompanied by generally adequate complementary foods, faltering in weight does not occur before 9 months among infants born with birth weights of more than 2500 g.

Age Factors↗
PubMed1995

Effects of exercise on plasma lipids and metabolism of lactating women.

To examine the effects of exercise on plasma lipids and metabolism during lactation, sedentary, exclusively breast-feeding women were randomly assigned to an exercise (E) or control (C) group at 6-8 wk postpartum. E subjects performed aerobic exercise 45 min.d-1, 5 d.wk-1, for 12 wk. Resting metabolic rate (RMR), energy expenditure, body composition, and dietary intake were measured at 6-8, 12-14, and 18-20 wk postpartum. Maximum oxygen uptake (VO2max), postprandial insulin, glucose, and thermic response, and plasma lipid levels were measured at 6-8 and 18-20 wk. VO2max increased by 25% vs 5% in the E vs the C group, respectively (P < 0.0001). RMR was similar between groups and did not change over time. Weight and percent body fat declined (P < 0.01) during the study, but there was no difference between E and C groups. Exercise marginally increased high-density lipoprotein cholesterol levels (P < 0.08), but did not affect other lipid concentrations. Insulin response decreased as VO2max increased (P = 0.05). There was no effect of time or group on glucose or thermic response. Exercise improves cardiovascular fitness during lactation, but does not increase the rate of postpartum weight loss.

Adipose Tissue↗
PubMed1994

Effects of age of introduction of complementary foods on infant breast milk intake, total energy intake, and growth: a randomised intervention study in Honduras.

In developing countries, the age at which breastfed infants are first given complementary foods is of public health importance because of the risk of diarrhoeal disease from contaminated weaning foods, and the potential risk of growth faltering if foods are inappropriately delayed. To evaluate whether there are any advantage of complementary feeding prior to 6 months, low-income primiparous mothers who had exclusively breastfed for 4 months were randomly assigned to one of 3 groups: continued exclusive breastfeeding to 6 months (EBF) (n = 50); introduction of complementary foods at 4 months with ad libitum nursing from 4-6 months (SF) (n = 47); and introduction of complementary foods at 4 months, with maintenance of baseline nursing frequency from 4-6 months (SF-M) (n = 44). Baby foods in jars were provided to the SF and SF-M groups from 4 to 6 months. Subjects were visited weekly and provided with lactation guidance; at 4, 5, and 6 months measurements were made of infant intake and breast milk composition. At 4 months, breast milk intake averaged 797 (139) g per day (no difference among groups). Between 4 and 6 months, breast milk intake was unchanged in EBF infants (+6) but decreased in the SF (-103), and SF-M (-62) groups (p < 0.001). Change in total energy intake (including solid foods) and infant weight and length gain did not differ significantly between groups. Weight and length gain from 4-6 months were comparable to those of breastfed infants in an affluent USA population. The results indicate that breastfed infants self-regulate their total energy intake when other foods are introduced. As a result, there is no advantage in introducing complementary foods before 6 months in this population, whereas there may be disadvantages if there is increased exposure to contaminated weaning foods.

Adult↗
PubMed1994

A randomized study of the effects of aerobic exercise by lactating women on breast-milk volume and composition.

BACKGROUND: The potential risks and benefits of regular exercise during lactation have not been adequately evaluated. We investigated whether regular aerobic exercise had any effects on the volume or composition of breast milk. METHODS: Six to eight weeks post partum, 33 sedentary women whose infants were being exclusively breast-fed were randomly assigned to an exercise group (18 women) or a control group (15 women). The exercise program consisted of supervised aerobic exercise (at a level of 60 to 70 percent of the heart-rate reserve) for 45 minutes per day, 5 days per week, for 12 weeks. Energy expenditure, dietary intake, body composition, and the volume and composition of breast milk were assessed at 6 to 8, 12 to 14, and 18 to 20 weeks post partum. Maximal oxygen uptake and the plasma prolactin response to nursing were assessed at 6 to 8 and 18 to 20 weeks. RESULTS: The women in the exercise group expended about 400 kcal per day during the exercise sessions but compensated for this energy expenditure with a higher energy intake than that recorded by the control women (mean [+/- SD], intake, 2497 +/- 436 vs. 2168 +/- 328 kcal per day at 18 to 20 weeks; P < 0.05). Maximal oxygen uptake increased by 25 percent in the exercising women but by only 5 percent in the control women (P < 0.001). There were no significant differences between the two groups in maternal body weight or fat loss, the volume or composition of the breast milk, the infant weight gain, or maternal prolactin levels during the 12-week study. CONCLUSIONS: In this study, aerobic exercise performed four or five times per week beginning six to eight weeks post partum had no adverse effect on lactation and significantly improved the cardiovascular fitness of the mothers.

Adult↗