Seasonal changes in activity, birth weight and lactational performance in rural Gambian women

Rural and urban migration to Europe in relation to cardiovascular disease risk: does it matter where you migrate from?

OBJECTIVES

To assess whether the environmental context (i.e. rural vs urban) in which individuals in low- and middle-income countries have resided most of their lives is associated with estimated cardiovascular disease (CVD) risk after migration to a high-income country.

STUDY DESIGN

Data from the Research on Obesity and Diabetes among African Migrants (RODAM) study were used including 1699 Ghanaian participants aged 40-79 years who had migrated to Europe from Ghana (1549 of urban origin, 150 of rural origin).

METHODS

Ten-year CVD risk was estimated using the Pooled Cohort Equation, with estimates ≥7.5% defining elevated CVD risk. Comparisons between urban and rural origin migrant groups were made using proportions and adjusted odds ratios (ORs).

RESULTS

The proportion of migrants with an elevated CVD-risk score was substantially higher among rural migrants than among urban migrants (45% vs. 37%, OR = 1.44, 95% confidence interval [CI]:1.03-2.02), which persisted after adjustment for education level, site of residence in Europe (London, Amsterdam or Berlin), length of stay in Europe, physical activity, energy intake and alcohol consumption (OR = 1.67, 95% CI: 1.05-2.67).

CONCLUSION

Our findings indicate that migrants who spent most of their lives in a rural setting before migration to Europe may have a higher CVD risk than those of urban origins. Further work is needed to confirm these findings in other migrant populations and to unravel the mechanisms driving the differential CVD risk between urban and rural migrants.

A systematic review on the association of month and season of birth with future anthropometric measures

BACKGROUND

Prenatal factors might have some health impacts later in life. This study aims to systematically review the current literature on the association between season and month of birth with birth weight as well as with weight status in childhood.

METHODS

The search process was conducted in electronic databases, including papers published until April 2019 in ISI Web of Science, PubMed, Scopus, and Google Scholar. The following search strategy was used with MeSH terms: ("Seasons"[Mesh]) AND ("Obesity"[Mesh] OR "Pediatric Obesity"[Mesh] OR "Obesity, Abdominal"[Mesh] OR "Overweight"[Mesh] OR "Birth Weight"[Mesh] OR "Body Height"[Mesh]). After the selection process, 50 papers were included in this systematic review.

RESULTS

This review showed that individuals who are born in cold season (winter month) have higher body mass index (BMI) and weight in childhood. Birth in March was associated with lower weight and BMI in boys according to most studies. All studies, except one of them, showed that season/month of birth was not associated with birth weight.

CONCLUSIONS

This systematic review confirms a relationship between season and month of birth with birth weight and body size in childhood; however, the impact of confounding factors, for example, vitamin D status, should be considered in the underlying pathway of this association.

IMPACT

The results provide evidence for the effect of season and month of birth on body size in childhood. Our systematic review suggests that there is no pattern between birth weight and season/month of birth, and the occurrence of low birth weight was more frequent among infants who were born in summer than others. Further research should focus on identifying the impact of confounding factors, for example, vitamin D status in the underlying pathway of this association. There was response to the controversial findings about the effect of environment factors, such as season and month of birth, and future anthropometric indices, such as obesity, weight, height, and birth weight. Obesity is a complex and multifactorial disorder; the findings of the current study would be useful in determining the relationship pathway between the season and the month of birth with other underlying factors for childhood obesity.

A protocol for an observational cohort study of heat strain and its effect on fetal wellbeing in pregnant farmers in The Gambia

Introduction: Climate change predictions indicate that global temperatures are likely to exceed those seen in the last 200,000 years, rising by around 4°C above pre-industrial levels by 2100 (without effective mitigation of current emission rates). In regions of the world set to experience extreme temperatures, women often work outside in agriculture even during pregnancy. The implications of heat strain in pregnancy on maternal health and pregnancy outcome are not well understood. This protocol describes a study to assess the physiological response of pregnant women to environmental heat stress and the immediate effect this has on fetal wellbeing.

Methods and analysis: The study will be performed in West Kiang district, The Gambia; a semi-arid zone in West Africa with daily maximum temperatures ranging from approximately 32 to 40°C. We will recruit 125 pregnant women of all ages who perform agricultural work during their pregnancy. Participants will be followed every two months until delivery. At each study visit fetal growth will be measured by ultrasound scan. During the course of their working day we will take the following measurements: continuous maternal physiological measurements (heart rate, respiratory rate, chest skin temperature and tri-axis accelerometer data); intermittent maternal tympanic core temperature, four point skin temperature, blood pressure; intermittent fetal heart rate and, if eligible, umbilical artery doppler; intermittent environmental measurements of air temperature, humidity, solar radiation and wind speed. Venous blood and urine will be collected at beginning and end of day for biomarkers of heat strain or fetal distress and hydration status.

A protocol for an observational cohort study of heat strain and its effect on fetal wellbeing in pregnant farmers in The Gambia

Introduction: Climate change predictions indicate that global temperatures are likely to exceed those seen in the last 200,000 years, rising by around 4°C above pre-industrial levels by 2100 (without effective mitigation of current emission rates). In regions of the world set to experience extreme temperatures, women often work outside in agriculture even during pregnancy. The implications of heat strain in pregnancy on maternal health and pregnancy outcome are not well understood. This protocol describes a study to assess the physiological response of pregnant women to environmental heat stress and the immediate effect this has on fetal wellbeing. Methods and analysis: The study will be performed in West Kiang district, The Gambia; a semi-arid zone in West Africa with daily maximum temperatures ranging from approximately 32 to 40°C. We will recruit 125 pregnant women of all ages who perform agricultural work during their pregnancy. Participants will be followed every two months until delivery. At each study visit fetal growth will be measured by ultrasound scan. During the course of their working day we will take the following measurements: continuous maternal physiological measurements (heart rate, respiratory rate, chest skin temperature and tri-axis accelerometer data); intermittent maternal tympanic core temperature, four point skin temperature, blood pressure; intermittent fetal heart rate and, if eligible, umbilical artery doppler; intermittent environmental measurements of air temperature, humidity, solar radiation and wind speed. Venous blood and urine will be collected at beginning and end of day for biomarkers of heat strain or fetal distress and hydration status.

Physical activity and associated factors among pregnant women in Ethiopia: facility-based cross-sectional study

Background

Regular physical activity (PA) has health benefits, including reducing the risk of complications during pregnancy. In Ethiopia, little is known about PA status and its determinants among pregnant women. The purpose of this study was to assess PA status and associated factors among pregnant women attending antenatal care at public and private health facilities in Mekelle, Ethiopia.

Methods

A facility-based cross-sectional study was conducted. Data was collected from 299 pregnant women using a structured questionnaire. Study participants were selected using a simple random sampling technique. A binary logistic regression was modeled to investigate the statistical significance of independent variables with PA status during pregnancy. Factors associated with PA status were estimated using adjusted odds ratios with 95% confidence intervals and statistical significance was declared at p-value < 0.05.

Results

79.3% of the study participants were classified as sedentary. The age group of 26–35 years (AOR: 2.69, 95% CI: 1.07–6.78), attending non-formal education (AOR: 13.50, 95% CI: 2.65–68.91), and women who did not work outside the home (AOR: 5.23, 95% CI: 1.34–20.38) were significantly associated with a higher risk of sedentary activity status. Pregnant women who were married (AOR: 0.26, 95% CI: 0.09–0.73), had two children (AOR: 0.13, 95% CI: 0.03–0.59), traveled an hour or more to health facilities (AOR: 0.31, 95% CI: 0.11–0.89) were protected from being sedentary.

Conclusion

Sedentary PA status was highly prevalent during pregnancy. Pregnant women in the age group of 26–35 years, with a non-formal education, and women who did not work outside the home had a greater risk of reporting being sedentary. Those who were married, had two children, and traveled an hour or more to health facilities were less likely to be sedentary. Stakeholders (Tigrai regional health bureau, Mekelle University, local NGOs working with pregnant women and societies at large) should give higher emphasis on designing appropriate strategies including educational interventions to overcome barriers to PA during pregnancy.

Life History theory hypotheses on child growth: Potential implications for short and long-term child growth, development and health

Life history theory integrates ecological, physiological, and molecular layers within an evolutionary framework to understand organisms' strategies to optimize survival and reproduction. Two life history hypotheses and their implications for child growth, development, and health (illustrated in the South African context) are reviewed here. One hypothesis suggests that there is an energy trade-off between linear growth and brain growth. Undernutrition in infancy and childhood may trigger adaptive physiological mechanisms prioritizing the brain at the expense of body growth. Another hypothesis is that the period from conception to infancy is a critical window of developmental plasticity of linear growth, the duration of which may vary between and within populations. The transition from infancy to childhood may mark the end of a critical window of opportunity for improving child growth. Both hypotheses emphasize the developmental plasticity of linear growth and the potential determinants of growth variability (including the role of parent-offspring conflict in maternal resources allocation). Implications of these hypotheses in populations with high burdens of undernutrition and infections are discussed. In South Africa, HIV/AIDS during pregnancy (associated with adverse birth outcomes, short duration of breastfeeding, and social consequences) may lead to a shortened window of developmental plasticity of growth. Furthermore, undernutrition and infectious diseases in children living in South Africa, a country undergoing a rapid nutrition transition, may have adverse consequences on individuals' cognitive abilities and risks of cardio-metabolic diseases. Studies are needed to identify physiological mechanisms underlying energy allocation between biological functions and their potential impacts on health.

Calorie restriction in humans: An update

Calorie restriction (CR), a nutritional intervention of reduced energy intake but with adequate nutrition, has been shown to extend healthspan and lifespan in rodent and primate models. Accumulating data from observational and randomized clinical trials indicate that CR in humans results in some of the same metabolic and molecular adaptations that have been shown to improve health and retard the accumulation of molecular damage in animal models of longevity. In particular, moderate CR in humans ameliorates multiple metabolic and hormonal factors that are implicated in the pathogenesis of type 2 diabetes, cardiovascular diseases, and cancer, the leading causes of morbidity, disability and mortality. In this paper, we will discuss the effects of CR in non-obese humans on these physiological parameters. Special emphasis is committed to recent clinical intervention trials that have investigated the feasibility and effects of CR in young and middle-aged men and women on parameters of energy metabolism and metabolic risk factors of age-associated disease in great detail. Additionally, data from individuals who are either naturally exposed to CR or those who are self-practicing this dietary intervention allows us to speculate on longer-term effects of more severe CR in humans.

Maternal and early life nutrition and physical activity: setting the research and intervention agenda for addressing the double burden of malnutrition in South African children

Early life is important for later health outcomes, yet there are few studies which adequately address all of the potential early life insults that may affect later life health and growth trajectories. This is particularly evident in low- to middle-income countries such as South Africa, where women of childbearing age are particularly vulnerable to high levels of physical inactivity, malnutrition, and obesity. Pregnancy may therefore be an opportune time to change behaviours and improve maternal and offspring health outcomes, and decrease the inter-generational transfer of risk. We show clear evidence that physical activity and nutrition are important target areas for intervention during pregnancy and in the early years of life, yet that current literature in Africa, and specifically South Africa, is limited. We have outlined the available literature concerning the impact of maternal and early life nutrition and physical activity on the health status of South African children, and have provided some recommendations for future research and policy.

The role of seasonality on the diet and household food security of pregnant women living in rural Bangladesh: a cross-sectional study

OBJECTIVE

To investigate the association of seasonality with dietary diversity, household food security and nutritional status of pregnant women in a rural district of northern Bangladesh.

DESIGN

A cross-sectional study was conducted from February 2013 to February 2015. Data were collected on demographics, household food security (using the Household Food Insecurity Access Scale), dietary diversity (using the women's dietary diversity questionnaire) and mid-upper arm circumference. Descriptive statistics were used to explore demographics, dietary diversity, household food security and nutritional status, and inferential statistics were applied to explore the role of seasonality on diversity, household food security and nutritional status.

SETTING

Twelve villages of Pirganj sub-district, Rangpur District, northern Bangladesh.

SUBJECTS

Pregnant women (n 288).

RESULTS

Seasonality was found to be associated with dietary diversity (P=0·026) and household food security (P=0·039). Dietary diversity was significantly lower in summer (P=0·029) and spring (P=0·038). Food security deteriorated significantly in spring (P=0·006) and late autumn (P=0·009).

CONCLUSION

Seasons play a role in women's household food security status and dietary diversity, with food security deteriorating during the lean seasons and dietary diversity deteriorating during the second 'lesser' lean season and the season immediately after. Interventions that aim to improve the diet of pregnant women from low-income, subsistence-farming communities need to recognise the role of seasonality on diet and food security and to incorporate initiatives to prevent seasonal declines.

Maternal nutrition at conception modulates DNA methylation of human metastable epialleles

In experimental animals, maternal diet during the periconceptional period influences the establishment of DNA methylation at metastable epialleles in the offspring, with permanent phenotypic consequences. Pronounced naturally occurring seasonal differences in the diet of rural Gambian women allowed us to test this in humans. We show that significant seasonal variations in methyl-donor nutrient intake of mothers around the time of conception influence 13 relevant plasma biomarkers. The level of several of these maternal biomarkers predicts increased/decreased methylation at metastable epialleles in DNA extracted from lymphocytes and hair follicles in infants postnatally. Our results demonstrate that maternal nutritional status during early pregnancy causes persistent and systemic epigenetic changes at human metastable epialleles.

Seasonal and gestation stage associated differences in aflatoxin exposure in pregnant Gambian women

OBJECTIVE

Aflatoxin is known to cross the placental barrier and exposures in utero could influence genomic programming, foetal growth and development, resulting in long-term health effects. We aimed to determine aflatoxin exposure in Gambian women at two stages of pregnancy and during the rainy and dry seasons.

METHODS

We examined aflatoxin exposure in pregnant Gambian women at early (<16 weeks) and later (16 weeks onward) stages of pregnancy and at different times of the year, during the rainy (June to October 2009) or dry (November to May 2010) season, using aflatoxin-albumin adducts (AF-alb).

RESULTS

Mean AF-alb was higher during the dry season than in the rainy season, in both early and later pregnancy although the difference was strongest in later pregnancy. There was a modest increase in AF-alb in later than early pregnancy (geometric mean 41.8 vs. 34.5 pg/mg, P < 0.05), but this was restricted to the dry season when exposures were generally higher.

CONCLUSIONS

The study confirmed that Gambian pregnant women were exposed to aflatoxin throughout the pregnancy, with higher levels in the dry season. There was some evidence in the dry season that women in later pregnancy had higher AF-alb levels than those in earlier pregnancy. Further research on the effects of exposure to this potent mutagen and carcinogen throughout pregnancy, including the epigenetic modification of foetal gene expression and impact on pre- and post-natal growth and development, are merited.

DNA methylation potential: dietary intake and blood concentrations of one-carbon metabolites and cofactors in rural African women

BACKGROUND

Animal models show that periconceptional supplementation with folic acid, vitamin B-12, choline, and betaine can induce differences in offspring phenotype mediated by epigenetic changes in DNA. In humans, altered DNA methylation patterns have been observed in offspring whose mothers were exposed to famine or who conceived in the Gambian rainy season.

OBJECTIVE

The objective was to understand the seasonality of DNA methylation patterns in rural Gambian women. We studied natural variations in dietary intake of nutrients involved in methyl-donor pathways and their effect on the respective metabolic biomarkers.

DESIGN

In 30 women of reproductive age (18-45 y), we monitored diets monthly for 1 y by using 48-h weighed records to measure intakes of choline, betaine, folate, methionine, riboflavin, and vitamins B-6 and B-12. Blood biomarkers of these nutrients, S-adenosylhomocysteine (SAH), S-adenosylmethionine (SAM), homocysteine, cysteine, and dimethylglycine were also assessed monthly.

RESULTS

Dietary intakes of riboflavin, folate, choline, and betaine varied significantly by season; the most dramatic variation was seen for betaine. All metabolic biomarkers showed significant seasonality, and vitamin B-6 and folate had the highest fluctuations. Correlations between dietary intakes and blood biomarkers were found for riboflavin, vitamin B-6, active vitamin B-12 (holotranscobalamin), and betaine. We observed a seasonal switch between the betaine and folate pathways and a probable limiting role of riboflavin in these processes and a higher SAM/SAH ratio during the rainy season.

CONCLUSIONS

Naturally occurring seasonal variations in food-consumption patterns have a profound effect on methyl-donor biomarker status. The direction of these changes was consistent with previously reported differences in methylation of metastable epialleles. This trial was registered at www.clinicaltrials.gov as NCT01811641.

Level and intensity of objectively assessed physical activity among pregnant women from urban Ethiopia

Background

Women in low-income countries are generally considered to have a high physical workload which is sustained during pregnancy. Although most previous studies have been based on questionnaires a recent meta-analysis of doubly labeled water data has raised questions about the actual amount of physical activity performed. In this study we report objectively assessed levels of physical activity, cardiorespiratory fitness and muscular fitness among pregnant urban Ethiopian women, and their association with demographic characteristics and anthropometric measures.

Methods

Physical activity was measured for seven consecutive days in 304 women using a combined uniaxial accelerometer and heart rate sensor. Activity energy expenditure was determined using a group calibration in a branched equation model framework. Type and duration of activities were reported using a 24-hour physical activity recall and grip strength was assessed using a dynamometer.

Results

Median (interquartile-range, IQR) activity energy expenditure was 31.1 (23.7-42.0) kJ/kg/day corresponding to a median (IQR) physical activity level of 1.46 (1.39-1.58). Median (IQR) time in sedentary, light, and moderate-to-vigorous intensity was 1100 (999–1175), 303 (223–374) and 40 (22–69) min/day, respectively. Mean (standard deviation) sleeping heart rate was 73.6 (8.0) beats/min and grip strength was 21.6 (4.5) kg. Activity energy expenditure was 14% higher for every 10 cm² difference in arm muscle area and 10% lower for every 10 cm² difference in arm fat area and 10-week difference in gestational age.

Conclusion

The level and intensity of physical activity among pregnant women from urban Ethiopia is low compared to non-pregnant women from other low income countries as well as pregnant European women from high-income countries.

[The effects of season at time of birth on asthma and pneumonia in childhood and adulthood in a birth cohort in southern Brazil]

This study evaluated the effects of seasonal weather at time of birth and ambient temperature during the first six months of life on hospitalizations due to asthma and pneumonia in preschool children and on diagnosis of asthma in adulthood among individuals from the 1982 birth cohort in Pelotas, Rio Grande do Sul, Brazil. The cohort included 5,914 live births, of which 77% were followed up until adulthood (23-24 yr). The risk of hospitalization due to pneumonia and asthma among children born from April to June (autumn) was 1.31 (95%CI: 0.99-1.73) to 2.4 (95%CI: 1.11-4.99) times higher than that of children born from January to March (summer). For temperature in the first six months of life, risk of hospitalization was 1.64 (95%CI: 1.26-2.13) to 3.16 (95%CI: 1.63-6.12) times higher for children born in the coldest as compared to the hottest temperature tertile. The effects of seasonality decreased with age, and the association with asthma in adulthood was weak. Hospitalizations in poor children were more frequent, but the effects of seasonality on pneumonia were more evident among the wealthiest.

Diet, energy expenditure, and body composition of lactating Ribeirinha women in the Brazilian Amazon

Lactation is the most energetically demanding part of human reproduction; yet, compared with pregnancy, we know little about the strategies women in different settings employ to cope with these increased energy demands. This paper takes a biocultural approach and reports longitudinal data on the anthropometry, dietary intakes and energy expenditure of a sample of 23 rural, lactating Ribeirinha women living in subsistence-based communities in the eastern Amazon. The dietary intakes of these lactating women were insufficient to meet their lactating energy needs and were least sufficient during resguardo, a 40-day period in the immediate postpartum when the women observed a series of food taboos and work restrictions. Instead, the women in this study met the increased energy demands of lactation by drawing on their energy reserves and reducing their energy expenditure in physical activity. The women showed a significant reduction in weight (P<0.001), BMI (P<0.001) and in circumferences (hip, P=0.01; waist, P=0.03) and skinfolds (thigh, P=0.03) in the gluteal femoral region. Total daily energy expenditure (TDEE) was lowest during resguardo and increased as lactation progressed (P=0.01). While the practice of resguardo reduced maternal energy expenditure and allowed women more time to spend with their newborn infants, it came at a cost (low dietary intake), which appears to be related to the loss of the adult woman from subsistence activities. By taking a biocultural approach this study illustrates the role the social environment plays in shaping the experience of lactating women.

Seasonal variations and trends in weight and arm circumference of non-pregnant rural Senegalese women, 1990–1997

OBJECTIVE

To describe levels, monthly variations and trends in weight and arm circumference of non-pregnant lactating women living in the Sahel, characterized by one short yearly rainy season (July-October).

METHODS

A mixed unbalanced cross-sectional longitudinal observational study conducted at 3, 5, 7 and 10 months postpartum among 3869 women living in the Sine area in central Senegal who had brought their infants into dispensaries for immunization from January 1990 to February 1997, and 1-5 consecutive children per woman (26 106 visits).

RESULTS

Mean weight was 55.7 kg (s.d.: 7.1), but it varied by 2.5-3.9 kg each year, from high means during the dry season (March-May) to low means at the end of the rainy season (September-November). The prevalence of underweight, overweight and obesity (body mass index (BMI)<18.5, 25-29.9 and >30 kg/m(2), respectively) was 7.6% (95% confidence interval: 7.3, 7.9), 6.4% (6.1, 6.7) and 0.4% (0.3, 0.4), but varied strongly by season (P<0.0001 for all). Unlike weight, mean arm increased during the early rains, a peak season of agricultural work (+0.10 cm/month (s.d.: 0.6) from June to August vs -0.35 kg/month (s.d.: 1.1) for weight). BMI and arm circumference were positively associated with age (mean: 20.8 vs 22.2 kg/m(2) and 25.3 vs 27.4 cm, at 20-24 and 40-49 years, respectively, P<0.0001 for both).

CONCLUSIONS

Season was a major determinant of the anthropometric status of rural African women. Negative energy balance reduced body weight from the onset of agricultural labour, while arm circumference increased during early rains, probably due to high physical activity.

Energy requirements during pregnancy and lactation

Objective

To estimate the energy requirements of pregnant and lactating women consistent with optimal pregnancy outcome and adequate milk production.

Design

Total energy cost of pregnancy was estimated using the factorial approach from pregnancy-induced increments in basal metabolic rate measured by respiratory calorimetry or from increments in total energy expenditure measured by the doubly labelled water method, plus energy deposition attributed to protein and fat accretion during pregnancy.

Setting

Database on changes in basal metabolic rate and total energy expenditure during pregnancy, and increments in protein based on measurements of total body potassium, and fat derived from multi-compartment body composition models was compiled. Energy requirements during lactation were derived from rates of milk production, energy density of human milk, and energy mobilisation from tissues.

Subjects

Healthy pregnant and lactating women.

Results

The estimated total cost of pregnancy for women with a mean gestational weight gain of 12.0 kg, was 321 or 325 MJ, distributed as 375, 1200, 1950 kJ day-1, for the first, second and third trimesters, respectively. For exclusive breastfeeding, the energy cost of lactation was 2.62 MJ day-1 based on a mean milk production of 749 g day-1, energy density of milk of 2.8 kJ g-1, and energetic efficiency of 0.80. In well-nourished women, this may be subsidised by energy mobilisation from tissues on the order of 0.72 MJ day-1, resulting in a net increment of 1.9 MJ day-1 over non-pregnant, non-lactating energy requirements.

Conclusions

Recommendations for energy intake of pregnant and lactating women should be updated based on recently available data.

Dietary diversity scores and nutritional status of women change during the seasonal food shortage in rural Burkina Faso

In developing countries, dietary diversity is usually assessed during a single yearly period and the effects of seasonal variations remain unknown. We studied these variations in women living in a Sahelian rural area (Burkina Faso). A representative sample of 550 women was surveyed at the beginning and at the end of the seasonal cereal shortage in April and September 2003, respectively. For each season, a dietary diversity score (DDS) representing the number of food groups consumed over a 24-h period, was computed and nutritional status was assessed by the BMI. The DDS increased from 3.4 +/- 1.1 to 3.8 +/- 1.5 food groups between the beginning and the end of the shortage season (P < 0.0001), and the proportion of women exhibiting low DDS decreased from 31.6 to 8.1%. This was due to the consumption of foods available during the cereal shortage season and despite the decrease in the consumption of some purchased foods. The increase in DDS was lower in women for whom DDS was already high in April and vice versa. Over the same period, the percentage of underweight women (BMI <18.5 kg/m(2)) increased from 11.1 to 17.1%. The relation between DDS and the women's socioeconomic characteristics or nutritional status was weakened in September. Thus, in April, fewer women were underweight when their DDS was high than when it was medium or low [odds ratio = 0.3 (0.2; 0.6)], but not in September [odds ratio = 0.6 (0.3; 1.0)]. In such a context, it would be useful to measure dietary diversity at the beginning of the cereal shortage season, when many women exhibit low DDS.

Statistical modelling of the seasonality of preterm delivery and intrauterine growth restriction in rural Gambia

We have developed a methodology for comparing the seasonal influences on two outcomes, when those influences may act cumulatively or instantaneously. We have used this to compare the seasonal pattern of intrauterine growth retardation (IUGR, as reflected by weight-for-gestational-age) and preterm delivery (as assessed by Dubowitz scoring) among 1718 infants born in rural Gambia. Both outcomes were analysed as binary variables: small-for-gestational-age (SGA, <10th centile of reference standard) and preterm (<37 weeks) respectively. Percentages of preterm and SGA babies show divergent seasonal patterns that might indicate separate aetiologies. However, seasonal effects influencing intrauterine growth are likely to be cumulative over the last few months of pregnancy. By modelling seasonality with truncated Fourier series we were able to deconvolve the underlying seasonal influences on fetal growth from the pattern for SGA. This enabled us to use seemingly unrelated biprobit regression to compare the underlying seasonal pattern of intrauterine growth with that governing the incidence of preterm delivery. We conclude that, if the seasonal factors affecting intrauterine growth operate over more than the last 2 months of pregnancy, then the seasonal patterns of the factors causing IUGR and preterm delivery are indistinguishable if the factors are assumed to trigger preterm delivery immediately, but differ if preterm delivery is assumed to be programmed by factors acting at conception.

Total energy expenditure (H218O), physical activity level and milk output of lactating rural Bangladeshi tea workers and nontea workers

OBJECTIVE

To assess the total daily energy expenditure (TDEE), milk output and physical activity level (PAL) of chronically malnourished lactating women using the doubly labelled water method (DLW).

DESIGN

Prospective, longitudinal study designed to assess the extent of malnutrition and energetics of lactating tea workers and nontea workers.

SETTING

North-east Bangladesh on women working and living in the same tea estates.

SUBJECTS

Of an original cohort of 150 lactating women, 30 were selected to participate in this study when they were at about 12 months postpartum. One mother subsequently dropped out.

INTERVENTIONS

On day 1 each women provided a urine sample, was administered a dose of DLW and 6 h later provided another sample. Further urine samples were collected for 21 subsequent days. In addition, every 5 days the mother provided a milk sample and at the same time her baby provided a urine sample.

RESULTS

Mean (s.d.) BMI was 17.4 (1.63). Mean TDEE and PAL were significantly higher in workers than nonworkers (8.42 (1.38) and 6.83 (2.09) MJ/day, P = 0.02 and 1.92 (0.34) and 1.59 (0.44), P = 0.03, respectively). Mean milk output was similar in the two groups (672 (180) ml and 749 (189) ml in workers and nonworkers, respectively).

CONCLUSIONS

Based on international BMI cutoffs, 79% of mothers were suffering from some degree of chronic energy deficiency. A total of 35% of workers and 17% of nonworkers were engaged in strenuous physical activity. The mean milk output of both workers and nonworkers was not different and was high especially as most of the mothers were about 12 months postpartum. No relationship was found between menses return and any of the variables studied.

SPONSORSHIP

World Health Organization, Nestle Foundation, UNICEF.

Sex and death: what is the connection?

A cost of reproduction, where lifespan and fecundity are negatively correlated, is of widespread occurrence. Mutations in insulin/IGF signaling (IIS) pathways and dietary restriction (DR) can extend lifespan in model organisms but do not always reduce fecundity, suggesting that the link between lifespan and fecundity is not inevitable. Understanding the molecular basis of the cost of reproduction will be informed by elucidation of the mechanisms by which DR and IIS affect these two traits.

Differential effects of seasonality on preterm birth and intrauterine growth restriction in rural Africans

BACKGROUND

Low birth weight (LBW) can result from prematurity or intrauterine growth restriction (IUGR) and result in small-for-gestational-age (SGA) infants. Prematurity and IUGR may have different etiologies and consequences.

OBJECTIVE

Our objective was to analyze seasonal patterns of prematurity and SGA in a rural African community and to compare them against variations in nutritional and ecologic variables that may provide insight into likely causative factors.

DESIGN

Fourier series were used to compare the seasonality of prematurity (<37 wk) and SGA (<10th percentile of the reference standard) among 1916 live infants born over 26 y in 3 Gambian villages. The resultant patterns were compared against monthly variations in birth frequency, maternal energy status, maternal work, and malaria infections.

RESULTS

The incidence of LBW was 13.3%, of prematurity was 12.3%, and of SGA was 25.1%. Prematurity and SGA showed divergent patterns of seasonality. Incidence of SGA was highest at the end of the annual hungry season, from August to December (peaking in November at 30.6%), with a nadir of 12.9% in June. Rates of SGA varied inversely with maternal weight changes. This pattern was not seen for rates of prematurity, which showed 2 peaks-in July (17.2%) and October (13.9%). The lowest proportion of preterm births occurred in February (5.1%). The peaks in prematurity closely paralleled increases in agricultural labor (July) and malaria infections (October).

CONCLUSION

We conclude that a reduction in LBW in such communities may require multiple interventions because of the variety of precipitating factors.

Energy restriction and aging

PURPOSE OF REVIEW

The focus of this review is on current research involving long-term calorie restriction and the resulting changes observed in possible biomarkers of aging. Special emphasis will be given to the basic and clinical science studies which are currently investigating the effects of controlled, high-quality energy-restricted diets on both biomarkers of longevity and on the development of chronic diseases related to age and obesity in humans.

RECENT FINDINGS

Prolonged calorie restriction has been shown to extend both the median and maximal lifespan in a variety of lower species such as yeast, worms, fish, rats, and mice. Mechanisms of this lifespan extension via calorie restriction are not fully elucidated, but possibly involve significant alterations in energy metabolism, oxidative damage, insulin sensitivity, and functional changes in both the neuroendocrine and sympathetic nervous systems. Ongoing studies of prolonged energy restriction in humans are now making it possible to analyze changes in these aging biomarkers to unravel some of the mechanisms of its antiaging phenomenon.

SUMMARY

With the incremental expansion of research endeavors in the area of energy or calorie restriction, data on the effects of calorie restriction in animal models and humans are becoming more accessible. Detailed analyses from controlled human trials involving long-term calorie restriction will allow investigators to link observed alterations in body composition down to changes in molecular pathways and gene expression, with their possible effects on the biomarkers of aging.

Calorie restriction and aging: review of the literature and implications for studies in humans

Calorie restriction (CR) extends life span and retards age-related chronic diseases in a variety of species, including rats, mice, fish, flies, worms, and yeast. The mechanism or mechanisms through which this occurs are unclear. CR reduces metabolic rate and oxidative stress, improves insulin sensitivity, and alters neuroendocrine and sympathetic nervous system function in animals. Whether prolonged CR increases life span (or improves biomarkers of aging) in humans is unknown. In experiments of nature, humans have been subjected to periods of nonvolitional partial starvation. However, the diets in almost all of these cases have been of poor quality. The absence of adequate information on the effects of good-quality, calorie-restricted diets in nonobese humans reflects the difficulties involved in conducting long-term studies in an environment so conducive to overfeeding. Such studies in free-living persons also raise ethical and methodologic issues. Future studies in nonobese humans should focus on the effects of prolonged CR on metabolic rate, on neuroendocrine adaptations, on diverse biomarkers of aging, and on predictors of chronic age-related diseases.

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.

Thermal environment and human birth weight

Human birth weight is known to be influenced by several factors, including maternal energy supply, maternal stature, disease status, smoking status and gestation length. This article proposes that the thermal environment may be a further factor influencing birth weight. Experimental animal studies demonstrate clear effects of thermal stress on placental function and birth weight, but may have limited relevance for humans due to between-species differences in pregnancy physiology. Observational studies suggest an inverse relationship between environmental temperature and birth weight within and between human populations. Variation in maternal size, body fatness, pregnancy weight gain and heat production is predicted to influence maternal thermoregulatory capacity, as are the size and composition of the foetus. These associations generate the hypothesis that low birth weight in hot environments may in part represent an adaptation to environmental heat stress.

Physiologic effects of lowering caloric intake in nonhuman primates and nonobese humans

Caloric restriction (CR) reduces the rate of aging and increases life span in all small animal species studied to date, but the effects of CR in humans remain uncertain. This review summarizes current knowledge of the effects of CR in nonhuman primates and humans. The results suggest that CR has a range of beneficial effects in nonhuman primates studied under laboratory conditions, and short-term markers of CR seen in animal models appear to occur in humans subject to CR also. However, the overall benefit of CR in human populations remains to be established, and studies in human populations are needed.

Pregnancy outcome for nomadic Turkana pastoralists of Kenya

The outcome of an individual pregnancy is a key component of overall reproductive success and is strongly influenced by environmental, behavioral, and biological variation within populations. This prospective study examined the outcomes of 68 pregnancies among nomadic Turkana of Kenya from July 1993 to July 1994. A total of 12 women experienced pregnancy losses, and 3 women experienced live births with a subsequent perinatal death. The following characteristics are associated with increased risk for experiencing a fetal or perinatal death: severe morbidity episodes, shorter nonpregnant intervals, lower third-trimester weight, higher third-trimester summed skinfolds but limited third-trimester reduction in summed skinfolds, and higher activity levels late in gestation. Turkana newborns measured within 48 hr of birth (n = 19) weighed an average of 2,860 +/- 640 g and had a mean ponderal index of 2.72 +/- 0.46. Variation in birth weight was predicted by preterm delivery, delivery during the wet season, and maternal morbidity levels. Birth length averaged 50.8 +/- 6.8 cm and was positively influenced by full term delivery, better maternal health, and birth during the dry season. These results suggest complicated pathways linking the physical environment, subsistence requirements, heterogeneity in maternal fitness, behavior, and pregnancy outcome. The results augment the larger picture of reproductive success for Turkana nomads who live in a highly variable savanna environment.

Daily energy expenditure across the course of lactation among urban Bangladeshi women

Measures of energy intake of lactating women in developing countries show that intakes are often lower than those recommended by international bodies, while fat-mass losses are often substantially less than the 3-4 kg used in the calculations of recommendations, suggesting that physiological adaptation must be commonplace among such women. The cost of lactation may be met by reduction in energy expenditure, including reduced physical activity, as well as by mobilization of bodily soft tissue. However, daily energy expenditure of lactating women has been shown to increase across the course of lactation among women in a rural population in the Philippines and an urban population in India, with a decline in body weight across the course of lactation in both studies. In the present study, total daily energy expenditure and anthropometric body composition were measured longitudinally in 68 mothers from a poor urban area of Dhaka, Bangladesh, at 0, 1, 2, 4, and 8 months of lactation, to determine whether the increasing energy expenditure across lactation observed elsewhere also occurs in Bangladeshi women. In addition, the extent to which an extended period of lactation was accompanied by weight and body fat change in these women was determined. Energy expenditure by heart-rate monitoring and activity report, and body composition from anthropometry was carried out four times across the 8-month period of lactation. A small decline in body fat mass and a significant increase in total energy expenditure across this period were observed, confirming similar observations elsewhere in the developing world.

Age, reproductive history, seasonality, and maternal body composition during pregnancy for nomadic Turkana of Kenya

To evaluate the potential differences in maternal nutritional investment in pregnancy, data collected from nomadic Ngisonyoka Turkana women during a July 1993-July 1994 field season were utilized. The roles maternal age, parity, duration of the previous nonpregnant interval, overlap between pregnancy and lactation on trimester changes in weight and summed skinfolds during pregnancy were examined. Because seasonality is an important aspect of the Turkana environment, the effects of seasonality were also assessed. First trimester weight gain is positively associated with overlap in pregnancy and lactation. Second trimester maternal weight gain is negatively influenced by higher parity and by overlap between lactation and early pregnancy. Third trimester weight gain is influenced only by seasonally induced morbidity. First trimester changes in maternal skinfolds are negatively influenced by older maternal age and parity, and positively influenced by a longer nonpregnant interval, and overlap between pregnancy and lactation. Second and third trimester skinfolds are significantly associated only with overlap between lactation and pregnancy (negatively in the second, positively in the third). Seasonality does not influence maternal skinfolds. Differences in age- and parity-related patterns of maternal nutritional investment in pregnancy are not supported by the data. The possibility that Turkana cultural beliefs may influence nutritional status during pregnancy is discussed. Am. J. Hum. Biol. 11:658-672, 1999. Copyright 1999 Wiley-Liss, Inc.

Energy intake and expenditure of free-living, pregnant Colombian women in an urban setting

BACKGROUND

This study examined the components of energy balance in poor, free-living pregnant women living in an urban setting of a developing country.

OBJECTIVES

We tested the following hypotheses: 1) energy intake increases in pregnancy and is greater than when nonpregnant and nonlactating (NPNL), 2) basal metabolic rate (BMR) increases in pregnancy and the increase is positively correlated with prepregnancy fatness, and 3) energy expenditure in activity decreases in pregnancy and is lower than in NPNL women.

DESIGN

Pregnant women were studied at 14.8 +/- 3.4 (n = 40), 25.0 +/- 3.2 (n = 54), and 34.9 +/- 2.4 (n = 43) wk gestation, and NPNL women at baseline (n = 114) and at 3 (n = 103) and 6 (n = 93) mo. Energy intake was measured by using estimated diet records and energy expenditure by using the flex heart rate method. Time allocation in physical activity was assessed by observation.

RESULTS

In pregnant women, body weight, BMR, and energy intake increased but total daily energy expenditure (TDEE) did not change significantly. There were no significant changes in time allocation to selected activities except for lying down. In comparison with NPNL control subjects, women in late pregnancy had higher energy intakes and BMRs. Values for TDEE were not significantly different, but pregnant women expended less energy in activity and allocated more time to 2 energy-saving activities and less time to 2 energy-demanding activities.

CONCLUSION

A decrease in energy expenditure in activity and changes in time allocation are important ways in which pregnant women meet the energy demands of pregnancy.

Longitudinal assessment of energy balance in well-nourished, pregnant women

BACKGROUND

Clinicians often recommend an additional energy intake of 1250 kJ/d to their pregnant patients. Previous studies have shown considerable variation in the metabolic response to pregnancy and thus in the additional energy required to support a pregnancy.

OBJECTIVE

The purpose of this study was to assess how well-nourished women meet the energy demands of pregnancy and to identify factors that predict an individual's metabolic response.

DESIGN

Resting metabolic rate (RMR), diet-induced thermogenesis (DIT), total energy expenditure (TEE), activity energy expenditure (AEE), energy intake (EI), and body fat mass (FM) were measured longitudinally in 10 women preconception; at 8-10, 24-26, and 34-36 wk of gestation; and 4-6 wk postpartum.

RESULTS

Compared with preconception values, individual RMRs increased from 456 to 3389 kJ/d by late pregnancy. DIT varied from -266 to 110 kJ/meal, TEE from -105 to 3421 kJ/d, AEE from -2301 to 2929 kJ/d, EI from -259 to 2176 kJ/d, and FM from a 0.6-kg loss to a 10.6-kg gain. The only prepregnant factor that predicted FM gain was RMR (r = 0.65, P < 0.05). Women with the largest cumulative increase in RMR deposited the least FM (r = -0.64, P < 0.05).

CONCLUSIONS

Well-nourished women use different strategies to meet the energy demands of pregnancy, including reductions in DIT or AEE, increases in EI, and deposition of less FM than anticipated. The combination of strategies used by individual women is not wholly predictable from prepregnant indexes. The use of a single recommendation for increased energy intake in all pregnant women is not justified.

Total energy expenditure and physical activity level of lactating Mesoamerindians

Energy-sparing mechanisms may be elicited to meet increased energy requirements imposed by lactation on women who reside in poor, rural communities in developing countries. The objectives of this study were to measure total energy expenditure and its components, basal and activity energy expenditure, and to investigate their relationships with lactation performance in a total of 40 rural Mesoamerindians stratified according to postpartum body mass index. Total energy expenditure and fat-free mass were measured by the doubly labeled water method, and basal metabolic rate was determined by indirect calorimetry at 3 and 6 mo postpartum. Physical activity level was taken as the ratio of total energy expenditure to basal metabolic rate. Milk energy output, which is not included in total energy expenditure, was computed from 24-h milk intake (test-weighing) and energy concentration of milk (bomb calorimetry). Anthropometric measurements revealed negligible mobilization of tissue stores. Mean (+/- SD) total energy expenditures were 8912 +/- 1296 kJ/d and 9253 +/- 1298 kJ/d for the lower and higher body mass index groups, respectively. Adjusted for fat-free mass, total energy expenditure was higher in the lower body mass index group (P = 0.05). Adjusted for fat-free mass, basal metabolic rate did not differ between groups. Physical activity level was significantly higher in the lower body mass index group (P = 0.03). Lactation performance did not differ between groups and was not associated with total energy expenditure or its components. Despite the maintenance of energy balance and heightened energy requirements of lactation, energy-sparing mechanisms were not evident in these lactating Mesoamerindians.

Applications of methods and techniques in the study of aerobic fitness during pregnancy

This article is a critical review of the general principles of exercise physiology and their relevance in pregnancy. An overview of the published studies and their conclusions are provided.

Beri-beri: age-gender bias in The Gambia

This paper investigates a suspected outbreak of beri-beri which occurred in The Gambia in 1988. The outbreak was spatially specific and had a distinct age and gender bias, with young men aged 15-49 being the group mainly affected. The age and gender bias of the outbreak is particularly interesting as women and children in the developing world are usually more susceptable to conditions associated with malnourishment, than men. The authors investigate the peculiar nature of the outbreak and find that they cannot easily explain the apparent age and gender bias. The authors note that at the time of the outbreak medical treatment took precedence over socio-economic investigations. This makes it difficult to ascertain why certain age and gender groups were affected and thus to target them for future preventative health education programmes. This case study therefore concludes, that where possible, medical investigations must be combined with socio-economic studies if future outbreaks of this kind are to be avoided.

Metabolic fuels and reproduction in female mammals

A complete reproductive cycle of ovulation, conception, pregnancy, and lactation is one of the most energetically expensive activities that a female mammal can undertake. A reproductive attempt at a time when calories are not sufficiently available can result in a reduced return on the maternal energetic investment or even in the death of the mother and her offspring. Numerous physiological and behavioral mechanisms link reproduction and energy metabolism. Reproductive attempts may be interrupted or deferred when food is scarce or when other physiological processes, such as thermoregulation or fattening, make extraordinary energetic demands. Food deprivation suppresses both ovulation and estrous behavior. The neural mechanisms controlling pulsatile release of gonadotropin-releasing hormone (GnRH) and, consequently, luteinizing hormone secretion and ovarian function appear to respond to minute-to-minute changes in the availability of metabolic fuels. It is not clear whether GnRH-secreting neurons are able to detect the availability of metabolic fuels directly or whether this information is relayed from detectors elsewhere in the brain. Although pregnancy is less affected by fuel availability, both lactational performance and maternal behaviors are highly responsive to the energy supply. When a reproductive attempt is made, changes in hormone secretion have dramatic effects on the partitioning and utilization of metabolic fuels. During ovulatory cycles and pregnancy, the ovarian steroids, estradiol and progesterone, induce coordinated changes in the procurement, ingestion, metabolism, storage, and expenditure of metabolic fuels. Estradiol can act in the brain to alter regulatory behaviors, such as food intake and voluntary exercise, as well as adenohypophyseal and autonomic outputs. At the same time, ovarian hormones act on peripheral tissues such as adipose tissue, muscle, and liver to influence the metabolism, partitioning and storage of metabolic fuels. During lactation, the peptide hormones, prolactin and growth hormone, rather than estradiol and progesterone, are the principal hormones controlling partitioning and utilization of metabolic fuels. The interactions between metabolic fuels and reproduction are reciprocal, redundant, and ubiquitous; both behaviors and physiological processes play vital roles. Although there are species differences in the particular physiological and behavioral mechanisms mediating nutrition-reproduction interactions, two findings are consistent across species: 1) Reproductive physiology and behaviors are sensitive to the availability of oxidizable metabolic fuels. 2) When reproductive attempts are made, ovarian hormones play a major role in the changes in ingestion, partitioning, and utilization of metabolic fuels.