Impact of lactation on maternal body weight and body composition

Impact of high-fat diet and exposure to constant light on reproductive competence of female ICR mice

Obesity and exposure to light at night are prevalent in modern society and associated with changes in physiology and behavior that can affect a female's ability to support offspring growth during pregnancy and lactation. A 2X3 factor study of ICR mice was conducted to determine the effect of diet [control (CON; 10% fat) or high fat (HF; 60% fat)] and exposure to regular 12 h light:dark cycles (LD) or continuous low (L5) or high (L100) lux of light on gestation length, birth litter size, milk composition and litter growth to lactation day 12. HF diet reduced birth litter size, but increased postnatal d 12 litter weight (P<0.05), whereas constant light tended to increase litter weight (P=0.07). Continuous light increased gestation length, altered dam feed intake, increased serum prolactin and increased final dam and mammary gland weight (P<0.05), while decreasing mammary ATP content and milk lactose (P<0.05). Correlation analysis indicated a positive relationship between final litter weight and mammary size, metabolic stores (e.g. maternal fat pad weight), kcal of feed intake, and gestation length (P<0.05). Although CON mice spent more time eating than HF dams, the calorically dense HF diet was related to greater rates of litter growth to peak lactation. Constant light circadian disrupting effects appear to be confounded by a potential long day photoperiod response exemplified by higher circulating levels of prolactin and increased body and mammary weight of females exposed to these conditions. Other model systems may be better to study the interacting effects of obesity and circadian disruption on reproductive competence.

Effects of Breastfeeding on Maternal Body Composition in Moroccan Lactating Women during Twelve Months after Birth Using Stable Isotopic Dilution Technique

BACKGROUND

Exclusive breastfeeding during the first six months of an infant's life is an important factor for their optimal growth and health. Breastfeeding also has maternal benefits and can assist with postpartum weight loss. As shown by previous studies, postpartum weight retention can contribute to obesity.

OBJECTIVE

To quantify the human milk and evaluate the effect of breastfeeding on maternal weight loss during the 12 months postpartum.

METHOD

This study included 70-mother-baby pairs. Infants' intake of human milk and water from other sources, as well as the body composition of the mothers, were measured at the 1st, 3rd, 6th, 9th and 12th month postpartum by using the deuterium oxide dose-to-mother technique.

RESULTS

There was a significant change in the mothers' body composition between the first and twelfth months in exclusive breastfeeding women compared to not-exclusive ones. Similarly, the difference between the quantities of human milk intake was highly significant in exclusive breastfeeding women compared to women who were not exclusively breastfeeding.

CONCLUSION

Our results showed that exclusive breastfeeding for twelve months has a significant effect on postpartum weight loss among Moroccan women and that it is an effective way to control overweight and obesity among lactating women.

Differential expression of fatty acid transporters and fatty acid synthesis-related genes in crop tissues of male and female pigeons (Columba livia domestica) during incubation and chick rearing

1. The growth performance of squabs reared solely by male or female parent pigeons was measured, and the changes of lipid content of crop milk and the expression profiles of genes potentially involved in lipid accumulation by crop tissues of parent pigeons were evaluated during incubation and chick rearing. 2. Squabs increased in body weight during 25 d of rearing, whereas both male and female pigeons lost weight after finishing rearing chicks, and the weight loss of male pigeons was significantly greater than that of female parent pigeons. Lipid content of crop milk from both parent pigeons gradually decreased to the crude fat level in the formulated diet after 10 d (R10) of chick rearing. 3. The gene expression of fatty acid translocase (FAT/CD36), fatty acid-binding protein 5 (EFABP) and acyl-CoA-binding protein (ACBP) in male pigeon crop tissue were the greatest at 17 d (I17) of incubation. In female pigeons, FAT/CD36 expression was the highest at I14, and both EFABP and ACBP expression peaked at I14 and R7. The expression of acetyl-CoA carboxylase and fatty acid synthase in male pigeons reached the maximum level at R1, while they peaked at I14 and I17, respectively in female pigeons. The gene expression of peroxisome proliferators-activated receptor-gamma (PPARγ) was the greatest at I17 in the male, while it was at I14 in the female. However, no regular changing pattern was found in PPARα gene expression in male pigeons. 4. These results indicated that male and female pigeons may make different contributions in rearing squabs. The gene expression study suggested that fatty acids used in lipid biosynthesis of crop milk probably originated from both exogenous supply and de novo synthesis. The sex of the parent pigeon affected the lipid content of crop milk and the expression profiles of genes involved in fatty acid transportation and lipogenesis.

Food insecurity, but not HIV-infection status, is associated with adverse changes in body composition during lactation in Ugandan women of mixed HIV status

BACKGROUND

Body composition is an important indicator of nutritional status and health. How body composition changes during 12 mo of breastfeeding in HIV-infected women receiving antiretroviral therapy (ART) is unknown.

OBJECTIVE

We assessed whether HIV or food insecurity was associated with adverse postpartum body-composition changes in Ugandan women.

DESIGN

A cohort of 246 women [36.5% of whom were HIV positive (HIV+) and were receiving ART] were followed to 12 mo postpartum. Repeated measures included weight, fat mass, fat-free mass, midupper arm circumference, triceps skinfold thickness [which allowed for the derivation of arm muscle area (AMA) and arm fat area (AFA)], breastfeeding, and individual food insecurity. Longitudinal regression models were constructed to assess associations between HIV and food insecurity and changes in body composition over time.

RESULTS

At baseline, HIV+ women compared with HIV-negative women had a higher mean ± SD food-insecurity score (11.3 ± 5.5 compared with 8.6 ± 5.5, respectively; P < 0.001) and lower AMA (40.6 ± 5.7 compared with 42.9 ± 6.9 cm³, respectively; P = 0.03). Participants were thin at 1 wk postpartum [body mass index (BMI; in kg/m²): 22.9 ± 2.9]. From 1 wk to 12 mo, the weight change was -1.4 ± 4.4 kg. In longitudinal models of body-composition outcomes, HIV was not associated with body composition (all P > 0.05), whereas food insecurity was inversely associated with body weight and BMI at 6, 9, and 12 mo and with AFA at 6 and 12 mo (all P < 0.05). At 6 mo, every 1-unit increase in the food-insecurity score was associated with a 0.13-kg lower body weight (P < 0.001) and a 0.26-cm³ lower AFA (P < 0.01).

CONCLUSIONS

Body-composition changes are minimal during lactation. HIV is not associated with body composition; however, food insecurity is associated with changes in body composition during lactation. This trial was registered at clinicaltrials.gov as NCT02922829 and NCT02925429.

Body composition in overweight and obese women postpartum: bioimpedance methods validated by dual energy X-ray absorptiometry and doubly labeled water

BACKGROUND/OBJECTIVES

Obesity, pregnancy and lactation all affect body composition. Simple methods to estimate body composition are useful in clinical practice and to evaluate interventions. In overweight and obese lactating women, such methods are not fully validated. The objective of this study was to validate the accuracy and precision of bioimpedance spectroscopy (BIS) by Xitron 4200 and 8-electrode multifrequency impedance (multifrequency bioimpedance analysis, MFBIA) by Tanita MC180MA with the reference methods dual energy X-ray absorptiometry (DXA) and doubly labeled water (DLW) for the assessment of body composition in 70 overweight and obese women postpartum.

SUBJECTS/METHODS

The LEVA-study (Lifestyle for Effective Weight loss during lactation) consisted of an intervention and follow-up with three assessments at 3, 6 and 15 months postpartum, which made possible the validation of both accuracy and precision. Mean differences between methods were tested by a paired t-test and Bland-Altman plots for systematic bias.

RESULTS

At baseline, BIS and MFBIA underestimated fat mass (FM) by 2.6±2.8 and 8.0±4.2 kg compared with DXA (P<0.001) but without systematic bias. BIS and MFBIA overestimated total body water (TBW) by 2.4±2.2 and 4.4±3.2 kg (P<0.001) compared with DLW, with slight systematic bias by BIS. BIS correctly estimated muscle mass without systematic bias (P>0.05). BIS overestimated changes in TBW (P=0.01) without systematic bias, whereas MFBIA varied greatly and with systematic bias.

CONCLUSIONS

BIS underestimates mean FM compared with DXA but can detect mean changes in body composition, although with large limits of agreement. BIS both accurately and precisely estimates muscle mass in overweight and obese women postpartum. MFBIA underestimates FM and overestimates TBW by proprietary equations compared with DXA and DLW.

Executive summary: Evaluating the evidence base to support the inclusion of infants and children from birth to 24 mo of age in the Dietary Guidelines for Americans--"the B-24 Project"

The Dietary Guidelines for Americans (DGA) are the cornerstone of US government efforts to promote health and prevent disease through diet and nutrition. The DGA currently provides guidelines for ages ≥ 2 y. In an effort to determine the strength of the evidence to support the inclusion of infants and children from birth to age 24 mo, the partner agencies led by the Department of Health and Human Services Office of Disease Prevention and Health Promotion and the USDA Center for Nutrition Program and Policy initiated the project entitled "Evaluating the evidence base to support the inclusion of infants and children from birth to 24 months of age in the Dietary Guidelines for Americans--the B-24 Project." This project represents the first step in the process of applying systematic reviews to the process of deciding whether the evidence is sufficient to include this age group in future editions of the DGA. This supplement includes the B-24 Executive Summary, which describes the B-24 Project and the deliberations of the 4 working groups during the process of developing priority topics for the systematic review, and a research agenda to address the critical gaps. Also included in this supplement issue is an article on the Nutrition Evidence Library methodology for developing systematic review questions and articles from the invited content presenters at the B-24 Prime meeting.

Maternal weight loss during exclusive breastfeeding is associated with reduced weight and length gain in daughters of HIV-infected Malawian women

Maternal weight loss during exclusive breastfeeding may influence the growth of exclusively breast-fed infants through impaired quality or quantity of breast milk. This study evaluated how maternal weight loss from 2 to 24 wk postpartum was related to infant weight and length gain in 1309 lactating HIV-infected mothers and their exclusively breast-fed infants. Malawian mother-infant pairs in the Breastfeeding, Antiretrovirals, and Nutrition Study were randomized with a 2 × 3 factorial design to a 2-arm nutritional intervention with a lipid-based nutrient supplement (LNS), meeting nutritional needs of lactation, or no LNS and a 3-arm antiretroviral (ARV) intervention (maternal, infant, or no ARV regimen). Linear regression models were used to relate maternal weight loss (weight loss vs. no weight loss) to infant weight and length gain from birth to 24 mo, stratifying by gender and controlling for maternal BMI at 2 wk (mean ± SD: 23.2 ± 3.0 kg/m(2)) and interacting maternal BMI with weight loss. In adjusted models, compared with daughters of women who did not lose weight, length and weight gain were lower in daughters whose mothers had a lower BMI at 2 wk postpartum coupled with the weight loss. For example, among mothers with an initial BMI of 18 kg/m(2), daughters of those who lost weight gained less weight [β = -0.29 kg (95% CI: -0.53, -0.06)] and length [β = -0.88 cm (95% CI: -1.52, -0.23)] from birth to 24 wk than daughters of those who gained weight. Though effects were only observed in girls, suggesting possible gender differences in suckling and feeding behavior, these findings indicate that maternal weight loss with low energy reserves represents a risk factor for poor infant growth outcomes.

Geographic distribution and socio-economic determinants of women's nutritional status in Mali households

OBJECTIVE

Mali is one of the poorest countries in Africa, with 72% of its population surviving on less than $US 1.00 per day. Health and demographic indicators are bleak. With few exceptions, studies related to the health of women in Mali have largely been under-represented. In addition, in recent years a new type of malnutrition stemming from weight gain and obesity has been observed throughout Africa. The present study aimed to (i) describe geographic and health variations of women of reproductive age, (ii) describe geographic variations of household salt iodine levels and (iii) investigate potential factors associated with women’s anthropometric status and use of adequately iodized salt among households in Mali.

DESIGN

Demographic and Health Survey data, multistage-stratified cluster sampling methodology.

SETTING

Rural and urban areas of Mali.

SUBJECTS

Non-pregnant women (n 6015) between the ages of 19 and 44 years.

RESULTS

Nineteen per cent of the women were overweight or obese while 11% were underweight. Seventy-eight per cent of the households utilized adequately iodized salt. Underweight women were more prevalent in southern Mali, while obesity was more frequent in the north-east and within the major urban areas. Households located within the southern parts of Mali were more likely to utilize adequately iodized salt. Education, age, modern contraceptive use, breast-feeding status at time of the survey and household wealth index were significantly associated with the women’s BMI or households’ use of adequately iodized salt.

CONCLUSIONS

The combined use of statistical and geographic system analysis contributes to improve targeting of interventions among vulnerable populations.

Predictors of postpartum weight change among overweight and obese women: results from the Active Mothers Postpartum study

BACKGROUND

The postpartum period may be critical for the development of midlife obesity. Identifying factors associated with postpartum weight change could aid in targeting women for healthy lifestyle interventions.

METHODS

Data from Active Mothers Postpartum (AMP), a study of overweight and obese postpartum women (n=450), were analyzed to determine the effect of baseline characteristics, breastfeeding, diet, physical activity, and contraception on weight change from 6 weeks to 12, 18, and 24 months postpartum. The repeated measures mixed model was used to test the association of these effects with weight change.

RESULTS

Although mean weight loss was modest (0.49 kg by 24 months), the range of weight change was striking (+21.5 kg to -24.5 kg, standard deviation [SD] 7.4). Controlling only for baseline weight, weight loss was associated with breastfeeding, hormonal contraception, lower junk food and greater healthy food intake, and greater physical activity. Only junk food intake and physical activity were significant after controlling for all other predictors.

CONCLUSIONS

Eating less healthy foods and being less physically active put overweight and obese women at risk of gaining more weight after a pregnancy.

Post-partum weight change patterns in the WHO Multicentre Growth Reference Study

The interplay of factors that affect post-partum loss or retention of weight gained during pregnancy is not fully understood. The objective of this paper is to describe patterns of weight change in the six sites of the World Health Organization (WHO) Multicentre Growth Reference Study (MGRS) and explore variables that explain variation in weight change within and between sites. Mothers of 1743 breastfed children enrolled in the MGRS had weights measured at days 7, 14, 28 and 42 post-partum, monthly from 2 to 12 months and bimonthly thereafter until 24 months post-partum. Height, maternal age, parity and employment status were recorded and breastfeeding was monitored throughout the follow-up. Weight change patterns varied significantly among sites. Ghanaian and Omani mothers lost little or gained weight post-partum. In Brazil, India, Norway and USA, mothers on average lost weight during the first year followed by stabilization in the second year. Lactation intensity and duration explained little of the variation in weight change patterns. In most sites, obese mothers tended to lose less weight than normal-weight mothers. In Brazil and Oman, primiparous mothers lost about 1 kg more than multiparous mothers in the first 6 months. In India and Ghana, multiparous mothers lost about 0.6 kg more than primiparas in the second 6 months. Culturally defined mother-care practices probably play a role in weight change patterns among lactating women. This hypothesis should stimulate investigation into gestational weight gain and post-partum losses in different ethnocultural contexts.

Maternal nutrition in rural Kenya: health and socio-demographic determinants and its association with child nutrition

High levels of food insecurity and human immunodeficiency virus (HIV) infection place most breastfeeding mothers in Kenya at high risk of malnutrition. We examined the role of selected socio-economic, demographic and health factors as determinants of nutritional status among HIV-infected and HIV-uninfected mothers in rural Kenya and further examined the interrelationship between maternal nutritional and child nutritional status within this population. A cross-sectional design was used to collect data from non-pregnant mothers with children ages 4-24 months in Kisumu District, Kenya. Over 80% of the mothers were breastfeeding at the time of the study. Mean maternal body mass index (BMI) (21.60 ± 3.15) and percent body fat (22.29 ± 4.86) values were lower than among lactating mothers in other Sub-Sahara African countries. Maternal HIV status was not significantly associated with any of the maternal nutritional indicators assessed in the study. Breastfeeding, recent severe illness and having multiple children below 2 years of age were negatively associated with maternal nutritional status, while higher maternal age, socio-economic status and household food security were each positively associated with maternal nutritional status. Significant positive association was reported between maternal weight, height, BMI, mid-upper arm circumference (MUAC), body fat and fat-free mass estimates, and children's height-for-age, weight-for-age, weight-for-height and MUAC-for-age z-score. This analysis identifies determinants of maternal nutritional status in rural Kenya and highlights the importance of interventions that address malnutrition in both HIV-infected and HIV-uninfected mothers in rural Kenya. Significant association between maternal and child nutritional status stresses the importance of addressing maternal and young child nutritional status as interrelated factors.

Predictors of breastfeeding in overweight and obese women: data from Active Mothers Postpartum (AMP)

Excess maternal weight has been negatively associated with breastfeeding. We examined correlates of breastfeeding initiation and intensity in a racially diverse sample of overweight and obese women. This paper presents a secondary analysis of data from 450 women enrolled in a postpartum weight loss intervention (Active Mothers Postpartum [AMP]). Sociodemographic measures and body mass index (BMI), collected at 6 weeks postpartum, were examined for associations with breastfeeding initiation and lactation score (a measure combining duration and exclusivity of breastfeeding until 12 months postpartum). Data were collected September 2004-April 2007. In multivariable analyses, BMI was negatively associated with both initiation of breastfeeding (OR: .96; CI: .92-.99) and lactation score (β -0.22; P = 0.01). Education and infant gestational age were additional correlates of initiation, while race, working full-time, smoking, parity, and gestational age were additional correlates of lactation score. Some racial differences in these correlates were noted, but were not statistically significant. Belief that breastfeeding could aid postpartum weight loss was initially high, but unrelated to breastfeeding initiation or intensity. Maintenance of this belief over time, however, was associated with lower lactation scores. BMI was negatively correlated with breastfeeding initiation and intensity. Among overweight and obese women, unrealistic expectations regarding the effect of breastfeeding on weight loss may negatively impact breastfeeding duration. In general, overweight and obese women may need additional encouragement to initiate breastfeeding and to continue breastfeeding during the infant's first year.

Effect of breast-feeding on weight retention at 3 and 6 months postpartum: data from the North Carolina WIC Programme

OBJECTIVE

Pregnancy-related weight retention can contribute to obesity, and breast-feeding may facilitate postpartum weight loss. We investigated the effect of breast-feeding on postpartum weight retention.

DESIGN

A retrospective follow-up study of weight retention, compared in women who were fully breast-feeding, combining breast-feeding with formula-feeding (mixed feeding), or formula-feeding at 3 months (n 14 330) or 6 months (n 4922) postpartum, controlling for demographic and weight-related covariates using multiple linear regression.

SETTING

The North Carolina Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).

SUBJECTS

Participants in the North Carolina WIC Programme who delivered a baby between 1996 and 2004.

RESULTS

In covariate-adjusted analyses, there was no association between breast-feeding and weight retention at 3 months postpartum. At 6 months postpartum, as compared to formula-feeders, mean weight retention was 0·84 kg lower in mixed feeders (95 % CI 0·39, 1·29; P = 0·0002) and 1·38 kg lower in full breast-feeders (95 % CI 0·89, 1·87; P ≤ 0·0001).

CONCLUSIONS

Breast-feeding was inversely associated with weight retention at 6 months postpartum in this large, racially diverse sample of low-income women. Further, full breast-feeding had a larger protective effect than did breast-feeding combined with formula-feeding.

Impact of Breastfeeding on Maternal Nutritional Status

This review covers the impact of breastfeeding on maternal postpartum weight loss and micronutrient status. Results regarding the impact on weight loss have been conflicting. This may be due to differences in study quality. Of six observational studies in which postpartum weight change was estimated (rather than measured directly), only one showed an association with breastfeeding. By contrast, six of the seven studies in which postpartum weight change was measured showed greater weight or fat loss in women who breastfed longer, particularly at 3 to 6 months postpartum. The results of the higher quality studies are consistent with two experimental studies conducted in Honduras, which demonstrated that the degree of breastfeeding affects the rate of weight loss. Thus, it appears that breastfeeding does enhance the rate of weight loss postpartum, but the effect is relatively small and may not be detectable in studies that lack adequate statistical power, have imprecise data on postpartum weight change, or do not account for the exclusivity and/or duration of breastfeeding. There is very little information with regard to micronutrient status during lactation. Nutrient requirements for vitamins A, B6, and C, and for iodine and zinc are increased by more than 50%, but lactation may actually be protective against maternal iron deficiency. More research is needed on the effects of lactation on maternal nutritional status and on strategies for optimizing nutrient intake to meet the needs of both the mother and her infant.

Effect of lactation on maternal body weight: a systematic review

The impact of lactation on maternal weight after delivery remains unclear. To address this question, we performed a systematic review of the literature. We searched PubMed, POPLINE, EMBASE, and LILACS computerized databases for relevant articles and classified the evidence using the U.S. Preventive Services Task Force rating system. We found 42 studies, of which 28 contained relevant information: 15 prospective cohort studies, 1 retrospective cohort study, 1 cross-sectional study, and 11 case-series reports. The methods used in these studies varied widely, thus precluding aggregation of results. Level II-2 and III evidence supports a class "C" recommendation: insufficient evidence exists to support an effect of lactation on maternal weight after delivery. Better longitudinal studies with a clear definition of breast-feeding; clear, specific outcome measures; study periods extending 1 or 2 years after delivery; and better control of potentially confounding factors will be needed to resolve this question.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to compile the literature on the effect of lactation on maternal weight, to compare the various studies, and to summarize the data on the effect of lactation on maternal weight gain.

Associations between reproduction and maternal body weight: examining the component parts of a full reproductive cycle

OBJECTIVE

Many transitional societies currently face both extremes of nutritional status, undernutrition and overnutrition. Women of reproductive age are at high risk of these conditions. The purpose of this review is to consider evidence for relationships between reproduction and nutritional status in women from societies of varying economic development, using body weight or weight-for-height as indicators of maternal nutritional status.

DESIGN

The conceptual framework guiding this review is that the duration of the reproductive cycle varies as a function of its component parts, which include (i) pregnancy, (ii) lactation, (iii) the non-pregnant/non-lactating (NP/NL) interval or, possibly, (iv) an overlap between lactation and next pregnancy. All component parts of the complete cycle vary in length and are associated with changes in nutritional status. A variety of factors ('proximal and distal determinants') influence the duration of the component parts of the reproductive cycle. This framework is used to examine current knowledge of changes in maternal nutritional status during each of these parts.

RESULTS

Women in affluent societies retain some weight with each pregnancy, beyond that of non-pregnant women. Women in less affluent societies retain less weight with each pregnancy. During lactation, women in both affluent and less affluent societies experience only modest weight loss. During the NP/NL interval, women in affluent societies tend to gain weight, whereas weight of women in less affluent societies is likely to fluctuate.

CONCLUSIONS

We conclude that there is a dearth of information on certain parts of the cycle, particularly the periods of overlap of lactation with pregnancy and the NP/NL interval.

Position of the American Dietetic Association: breaking the barriers to breastfeeding

It is the position of the American Dietetic Association (ADA) that broad-based efforts are needed to break the barriers to breastfeeding initiation and duration. Exclusive breastfeeding for 6 months and breastfeeding with complementary foods for at least 12 months is the ideal feeding pattern for infants. Increases in initiation and duration are needed to realize the health, nutritional, immunological, psychological, economical, and environmental benefits of breastfeeding. Breastfeeding initiation rates have increased, but cultural barriers to breastfeeding, especially against breastfeeding for 6 months and longer, still exist. Gaps in rates of breastfeeding based on age, race, and socioeconomic status remain. Children benefit from the biologically unique properties of human milk including protection from illness with resulting economic benefits. Mother's benefits include reduced rates of premenopausal breast and ovarian cancers. Appropriate lactation management is a critical component of successful breastfeeding for healthy women. Lactation support and management is even more important in women and children with special needs caused by physical or developmental disability, disease, or limited resources. Dietetics professionals have a responsibility to support breastfeeding through appropriate education and training, advocacy, and legislative action; through collaboration with other professional groups; and through research to eliminate the barriers to breastfeeding.

Perinatal metabolism of dichlorodiphenyldichloroethylene in Nicaraguan mothers

Umbilical cord and venous blood samples were collected at the time of delivery from 52 mothers living in urban and rural areas of the Atoya River basin, Nicaragua. In a subsample of 24 mothers that delivered by Cesarean section, abdominal adipose tissue samples were also collected, as was breast milk later in lactation. Cord and venous blood sera were analyzed for 13 organochlorine pesticides: 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (pp'-DDT); 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (pp'-DDE); pp'-dichlorophenyldichlorodiene (pp'-DDD); alpha-hexachlorocyclohexane (alpha-HCH); beta-hexachlorocyclohexane (beta-HCH); gamma-hexachlorocyclohexane (gamma-HCH); delta-hexachlorocyclohexane (delta-HCH); toxaphene; dieldrin; endrin; aldrin; heptachlor; and heptachlor epoxide. In venous blood only pp'-DDE (100% of samples), pp'-DDT (1.92%), dieldrin (15.38%), heptachlor (15.38%), gamma-HCH (7.69%), beta-HCH (11.53%), and delta-HCH (1.92%) were found, whereas in cord blood only pp'-DDE (100%), pp'-DDT (3.84%), dieldrin (19.23%), and heptachlor (9.16%), were found. The persistent DDT metabolite pp'-DDE, present in all samples of blood serum, adipose tissue, and breast milk, was studied in relation to maternal characteristics such as body mass index (BMI), age, lactation experience, and fetal pesticide acquisition. Mean venous (7.12 microg/g) and cord (6.39 microg/g) pp'-DDE concentrations were not significantly different but were significantly correlated. pp'-DDE in maternal adipose tissue was positively correlated with pp'-DDE in cord blood (P=0.0001) and breast milk (P<0.0001) and marginally correlated with changes in BMI (r=-0.03088; P=0.06). There was a higher proportion of samples (58%) with a greater concentration of DDE in venous than in cord blood. Although DDE accumulation may be less during fetal development than during breast feeding, exposure during embryogenesis may be more important than during the postnatal period.

Breastfeeding beyond 12 months. An historical perspective

A decade ago, child psychiatrist Coello-Novello, in her term as Surgeon General of the United States, said, "It's the lucky baby, I feel, who continues to nurse until he's two." The accumulated evidence supports her statement. The understanding of the benefits of breastfeeding beyond 12 months should support the cultural change in which eventually prolonged breastfeeding becomes normal.

Effects of exclusive breastfeeding for four versus six months on maternal nutritional status and infant motor development: results of two randomized trials in Honduras

To examine whether the duration of exclusive breastfeeding affects maternal nutrition or infant motor development, we examined data from two studies in Honduras: the first with 141 infants of low-income primiparous women and the second with 119 term, low birth weight infants. In both studies, infants were exclusively breastfed for 4 mo and then randomly assigned to continue exclusive breastfeeding (EBF) until 6 mo or to receive high-quality, hygienic solid foods (SF) in addition to breast milk between 4 and 6 mo. Maternal weight loss between 4 and 6 mo was significantly greater in the exclusive breastfeeding group (EBF) group than in the group(s) given solid foods (SF) in study 1 (-0.7 +/- 1.5 versus -0.1 +/- 1.7 kg, P < 0.05) but not in study 2. The estimated average additional nutritional burden of continuing to exclusively breastfeed until 6 mo was small, representing only 0.1-6.0% of the recommended dietary allowance for energy, vitamin A, calcium and iron. Women in the EBF group were more likely to be amenorrheic at 6 mo than women in the SF group, which conserves nutrients such as iron. In both studies, few women (10-11%) were thin (body mass index <19 kg/m(2)), so the additional weight loss in the EBF group in study 1 was unlikely to have been detrimental. Infants in the EBF group crawled sooner (both studies) and were more likely to be walking by 12 mo (study 1) than infants in the SF group. Taken together with our previous findings, these results indicate that the advantages of exclusive breastfeeding during this interval appear to outweigh any potential disadvantages in this setting.