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Neonatal head circumference (HC) not only represents the brain size of Homo sapiens, but is also an important health risk indicator. Addressing a lack of comparative studies on head size and its variability in term and preterm neonates from different populations, we aimed to examine neonatal HC by gestation according to a regional reference and a global standard. Retrospective analysis of data on neonatal HC obtained from the Lithuanian Medical Birth Register from 2001 to 2015 (423 999 newborns of 24-42 gestational weeks). The varying distribution by gestation and sex was estimated using GAMLSS, and the results were compared with the INTERGROWTH-21st standard. Mean HC increased with gestation in both sexes, while its fractional variability fell. The 3rd percentile matched that for INTERGROWTH-21st at all gestations, while the 50th and 97th percentiles were similar up to 27 weeks, but a full channel width higher than INTERGROWTH-21st at term. INTERGROWTH-21st facilitates the evaluation of neonatal HC in early gestations, while in later gestations, the specific features of neonatal HC of a particular population tend to be more precisely represented by regional references., (© 2022. The Author(s).)

Objectives: Pelvic growth may be sensitive to early-life nutrition, with implications for maternal risk of obstructed labor. However, the "developmental origins" of adult pelvic variability require further investigation. We tested whether adult pelvic dimensions are associated with two components of height, indexing different periods of linear growth: tibia length, a proxy for early postnatal growth, and height-residual (height regressed on tibia length), a proxy for later growth. We also tested whether adult pelvic dimensions are associated with birth weight, a marker of nutritional investment in utero., Methods: In this cross-sectional study, data were obtained on 68 nulliparous young women of South Asian ancestry. Pelvic dimensions (bi-iliac and bi-acetabular breadth, anteroposterior pelvic inlet and outlet, interspinous and intertuberous diameter) were measured using magnetic resonance imaging. Height and tibia length were measured manually. Birth weight and gestational age were obtained by recall. Multivariable regression models were fitted with a given pelvic dimension regressed on height-residual, tibia, and birth weight, with the latter adjusted for gestational age., Results: Controlling for birth weight, height-residual was predictive of bi-acetabular breadth, bi-iliac breadth, and the pelvic inlet, while tibia length significantly predicted all dimensions except interspinous diameter. Controlling for the linear growth variables, birth weight was predictive of bi-iliac breadth only., Conclusions: Markers of linear growth during both early and later development were associated with adult pelvic dimensions, whereas size at birth was poorly predictive. Efforts to reduce stunting in early life may facilitate the attainment of maximum potential growth for both height and the pelvis., (© 2019 The Authors. American Journal of Human Biology published by Wiley Periodicals, Inc.)

The aim of this study was to determine if syndrome-specific birth weight charts were beneficial for babies with Down syndrome in England and Wales. Birth weights of 8,825 babies with Down syndrome born in England and Wales in 1989-2010 were obtained from the National Down Syndrome Cytogenetic Register. Birth weight centiles for 30-42 weeks gestation by sex were fitted using the LMS method and were compared to those for unaffected babies from the UK-WHO growth charts. For babies born with Down syndrome the median birth weight from 37 to 42 weeks was 2,970 g (10th-90th centile: 2,115-3,680) for boys and 2930 g (2,100-3,629) for girls, and the modal age of gestation was 38 weeks, 2 weeks earlier than for unaffected babies. At 38 weeks gestation they were only slightly lighter than unaffected babies (159 g for boys and 86 g for girls). However at 40 weeks gestation the shortfall was much greater (304 g and 239 g, respectively). In neonates with Down syndrome there is little evidence of growth restriction before 38 weeks gestation, so up to this age it is appropriate to use the UK-WHO birth weight charts. Thereafter birth weight is below that of unaffected babies and it should be plotted on the UK Down syndrome growth charts., (© 2015 Wiley Periodicals, Inc.)

How "healthy" do children need to be when selecting reference samples for spirometry? Anthropometry and spirometry were measured in an unselected, multi-ethnic population of school children aged 5-11 years in London, UK, with follow-up assessments 12 months later. Parents provided information on children's birth data and health status. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were adjusted for sex, age, height and ethnicity using the 2012 Global Lungs Initiative equations, and the effects of potential exclusion criteria on the z-score distributions were examined. After exclusions for current and chronic lung disease, acceptable data were available for 1901 children on 2767 occasions. Healthy children were defined as those without prior asthma or hospitalisation for respiratory problems, who were born at full-term with a birthweight ≥2.5 kg and who were asymptomatic at testing. Mean±sd z-scores for FEV1 and FVC approximated 0±1, indicating the 2012 Global Lungs Initiative equations were appropriate for this healthy population. However, if children born preterm or with low birthweight, children with prior asthma or children mildly symptomatic at testing were included in the reference, overall results were similar to those for healthy children, while increasing the sample size by 25%. With the exception of clear-cut factors, such as current and chronic respiratory disease, paediatric reference samples for spirometry can be relatively inclusive and hence more generalisable to the target population., (Copyright ©ERS 2015.)

The patterns of association between maternal or paternal and neonatal phenotype may offer insight into how neonatal characteristics are shaped by evolutionary processes, such as conflicting parental interests in fetal investment and obstetric constraints. Paternal interests are theoretically served by maximizing fetal growth, and maternal interests by managing investment in current and future offspring, but whether paternal and maternal influences act on different components of overall size is unknown. We tested whether parents' prepregnancy height and body mass index (BMI) were related to neonatal anthropometry (birthweight, head circumference, absolute and proportional limb segment and trunk lengths, subcutaneous fat) among 1,041 Australian neonates using stepwise linear regression. Maternal and paternal height and maternal BMI were associated with birthweight. Paternal height related to offspring forearm and lower leg lengths, maternal height and BMI to neonatal head circumference, and maternal BMI to offspring adiposity. Principal components analysis identified three components of variability reflecting neonatal "head and trunk skeletal size," "adiposity," and "limb lengths." Regression analyses of the component scores supported the associations of head and trunk size or adiposity with maternal anthropometry, and limb lengths with paternal anthropometry. Our results suggest that while neonatal fatness reflects environmental conditions (maternal physiology), head circumference and limb and trunk lengths show differing associations with parental anthropometry. These patterns may reflect genetics, parental imprinting and environmental influences in a manner consistent with parental conflicts of interest. Paternal height may relate to neonatal limb length as a means of increasing fetal growth without exacerbating the risk of obstetric complications., (© 2014 The Authors American Journal of Physical Anthropology Published by Wiley Periodicals, Inc.)

Background: Low birth weight has been consistently associated with adult chronic disease risk. The thrifty phenotype hypothesis assumes that reduced fetal growth impacts some organs more than others. However, it remains unclear how birth weight relates to different body components, such as circumferences, adiposity, body segment lengths and limb proportions. We hypothesized that these components vary in their relationship to birth weight., Methods: We analysed the relationship between birth weight and detailed anthropometry in 1270 singleton live-born neonates (668 male) from the Mater-University of Queensland Study of Pregnancy (Brisbane, Australia). We tested adjusted anthropometry for correlations with birth weight. We then performed stepwise multiple regression on birth weight of: body lengths, breadths and circumferences; relative limb to neck-rump proportions; or skinfold thicknesses. All analyses were adjusted for sex and gestational age, and used logged data., Results: Circumferences, especially chest, were most strongly related to birth weight, while segment lengths (neck-rump, thigh, upper arm, and especially lower arm and lower leg) were relatively weakly related to birth weight, and limb lengths relative to neck-rump length showed no relationship. Skinfolds accounted for 36% of birth weight variance, but adjusting for size (neck-rump, thigh and upper arm lengths, and head circumference), this decreased to 10%. There was no evidence that heavier babies had proportionally thicker skinfolds., Conclusions: Neonatal body measurements vary in their association with birth weight: head and chest circumferences showed the strongest associations while limb segment lengths did not relate strongly to birth weight. After adjusting for body size, subcutaneous fatness accounted for a smaller proportion of birth weight variance than previously reported. While heavier babies had absolutely thicker skinfolds, this was proportional to their size. Relative limb to trunk length was unrelated to birth weight, suggesting that limb proportions at birth do not index factors relevant to prenatal life.

Objective: To describe birth weight and postnatal weight gain in a contemporaneous population of babies born <32 weeks' gestation, using routinely captured electronic clinical data., Design: Anonymised longitudinal weight data from 2006 to 2011., Setting: National Health Service neonatal units in England., Methods: Birth weight centiles were constructed using the LMS method, and longitudinal weight gain was summarised as mean growth curves for each week of gestation until discharge, using SITAR (Superimposition by Translation and Rotation) growth curve analysis., Results: Data on 103 194 weights of 5009 babies born from 22-31 weeks' gestation were received from 40 neonatal units. At birth, girls weighed 6.6% (SE 0.4%) less than boys (p<0.0001). For babies born at 31 weeks' gestation, weight fell after birth by an average of 258 g, with the nadir on the 8th postnatal day. The rate of weight gain then increased to a maximum of 28.4 g/d or 16.0 g/kg/d after 3 weeks. Conversely for babies of 22 to 28 weeks' gestation, there was on average no weight loss after birth. At all gestations, babies tended to cross weight centiles downwards for at least 2 weeks., Conclusions: In very preterm infants, mean weight crosses centiles downwards by at least two centile channel widths. Postnatal weight loss is generally absent in those born before 29 weeks, but marked in those born later. Assigning an infant's target centile at birth is potentially harmful as it requires rapid weight gain and should only be done once weight gain has stabilised. The use of electronic data reflects contemporary medical management.

Background: The adoption in May 2009 by the UK of the WHO 2006 standard necessitated the provision of UK-based birth centiles for pre-term infants. The pre-existing British 1990 reference birth centiles, used in the UK since 1995, had been biased by the inclusion of post-natal data., Aim: To describe the construction of new UK birth centiles for weight, length and head circumference, based on British 1990 reference data, but excluding post-natal data., Subjects and Methods: Birth data from the five original studies, collected between 1983-1993, were pooled and analysed by the LMS method, for the sexes separately. In addition, sex-specific composite centiles were constructed for infants born at term (37-42 completed weeks)., Results: The birth data included 9443 weights, 985 lengths and 1841 head circumferences, covering 23-44 weeks gestation. The analysis provided LMS tables defining reference centiles for weight and head circumference from 23-42 weeks and for length from 26-42 weeks. The term centiles are for use at age 0 on the post-natal 0-1 year chart., Conclusion: These new centiles, replacing those of the British 1990 reference, are more accurate than their predecessors which were biased due to the inclusion of post-natal data.

Objective: In a prospective study, we investigated the impact of early growth on blood pressure at 3 years of age., Methods: We measured systolic blood pressure (SBP) and diastolic blood pressure (DBP) for 590 children 3 years of age and related measurements to current size and size at birth, 6 months, 1 year, and 2 years of age., Results: SBP was related positively to weight at 3 and 2 years and, after adjustment for current size, negatively to weight at birth and 6 months but not at 1 or 2 years. No effect was observed for DBP. A family history of hypertension was associated with higher maternal blood pressure, greater weight, and gestational hypertension (P = .05). Mothers with a history of gestational hypertension had higher SBP and DBP values (P < .001). In multivariate linear regression analyses, SBP was influenced positively by weight at 3 years and family history of hypertension and negatively by weight at 6 months. None of the factors was associated with DBP., Conclusions: For 3-year-old children, current weight was a determinant of SBP and postnatal growth to 6 months of age was more predictive than birth weight. A family history of hypertension is important in determining maternal blood pressure. These observations suggest a window in which postnatal growth might be modified.

Fracture risk is determined by bone mass, size and architecture. Birth weight (Bwt) is reported to predict adult bone mass and density. Early life environment may therefore be a determinant of bone strength in later life. However such evidence was obtained using dual energy X-ray absorptiometry (DXA), which is known to be dependent on size. We used peripheral quantitative computed tomography (pQCT) and DXA to investigate Bwt as a determinant of bone size and cross section area (CSA), bone mineral content (BMC) and volumetric bone mineral density (vBMD) and areal BMD (aBMD) independent of current weight, height and age. The study population consisted of 68 males and 52 nulliparous females aged 17 to 21years from Keneba, The Gambia. This population has a high prevalence of factors likely to influence skeletal development (poor nutrition, low calcium intake, late puberty and high physical activity). Measures of bone size and CSA, BMC and BMD were obtained using pQCT (Stratec 2000; at 4% and 66% radius; 4% and 50% tibia) and DXA (Lunar DPX; spine, hip, forearm and whole body). Sequential univariable (influence of Bwt on bone variables) and multivariable linear regression analyses (influence of Bwt on bone variables after adjusting for current height, weight and age) were used to investigate the independent effects of Bwt and attained size. Analyses were performed separately by sex. Bwt was a significant positive predictor of CSA at appendicular cortical sites in males and CSA and bone area at appendicular and most axial trabecular sites in females before and after adjustment for current height, weight and age. Bwt was not consistently related to BMC, vBMD or aBMD as measured by pQCT or DXA. Current weight was a positive predictor of aBMD and pQCT- and DXA-derived BMC in males and females. Height predicted aBMD and trabecular vBMD in males. In summary, Bwt significantly predicted attained CSA at cortical sites in males and at trabecular sites in females. Current weight was a positive predictor of BMC and aBMD in both sexes. This suggests that pre-natal factors affecting fetal growth may influence adult bone strength independently of post-natal factors., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

Objective: The influence of infant feeding practices on weight gain during childhood remains unresolved, with few studies adjusting appropriately for confounding factors. This study examined the effect of breastfeeding initiation, breastfeeding duration and age at introduction of solid foods on weight gain from birth to 3 years., Design: Nationally representative prospective study., Setting: England, Wales, Scotland and Northern Ireland., Participants: 10,533 3-year-old children from the UK Millennium Cohort Study., Main Outcome Measure: Conditional weight gain z-scores from birth to 3 years (adjusted for birthweight); multiple linear regression analyses were conducted to examine the impact of infant feeding practices on this measure after adjustment for confounding factors., Results: Breastfeeding initiation and breastfeeding duration were significantly associated with weight gain from birth to 3 years. Infants receiving no breast milk grew faster than those whose mothers initiated breastfeeding (adjusted regression coefficient (difference in z-scores) 0.06, 95% CI 0.02 to 0.09), as did those breastfed for less than 4 months (0.05, 95% CI 0.01 to 0.09) versus those breastfed 4 months or longer. Early introduction of solids was not associated with faster weight gain after adjustment for height z-score at 3 years (-0.01, 95% CI -0.04 to 0.03)., Conclusions: Initiating and prolonging breastfeeding may reduce excess weight gain by preschool age. Association of the early introduction of solids with rapid weight gain during early childhood is mediated through childhood stature. Although effects sizes are small, at a population level they are of public health importance as these risk factors are potentially modifiable. Strategies to support mothers to follow internationally recommended infant feeding practices are required.

Aims: To perform a longitudinal analysis of the association between childhood body mass index (BMI) and later risk of Type 1 diabetes, controlling for socio-economic status, birthweight, height in early and late childhood, breastfeeding history and pubertal status., Methods: Analysis of the 1970 British Birth Cohort, followed up at age 5, 10 and 30 years (n = 11,261). Data were available on birthweight, breastfeeding; height, weight, pubertal status, socio-economic status at age 10 years; self-report data on history of diabetes (type, age at onset) at age 30 years. Cox proportional hazards models were used to examine relations of childhood growth, socio-economic status and breastfeeding history to the incidence of Type 1 diabetes between 10 and 30 years of age., Results: Sixty-one subjects (0.5%) reported Type 1 diabetes at 30 years of age; 47 (77%) reported onset >or= age 10 years. Higher BMI z-score at 10 years predicted higher risk of subsequent Type 1 diabetes (hazard ratio 1.8, 95% confidence interval 1.2 to 2.8, P = 0.01) when adjusted for birthweight, pubertal status, breastfeeding history and socio-economic status. Repeating the model for childhood obesity, the hazard ratio was 3.1 (1.0, 9.3; P = 0.05). Birthweight, breastfeeding, height growth and pubertal timing were not associated with incidence of Type 1 diabetes., Conclusions: Higher BMI in childhood independently increased the risk of later Type 1 diabetes, supporting suggestions that obesity may provide a link between Type 1 and Type 2 diabetes. This supports observations of a rise in Type 1 diabetes prevalence. Reduction in childhood obesity may reduce the incidence of Type 1 as well as Type 2 diabetes.

Human growth is a continuous process. Studies defining factors influencing growth focus on discrete time points (e.g., birth), overlooking the conditional nature of the process. One thousand six hundred fifty Caucasian mothers who gave birth at term after an uncomplicated singleton pregnancy were studied using conditional analysis. Infant height, weight, and head circumference were obtained at birth and 6 mo of age. Data analysis, conditional upon birth size, was conducted as a stepped consideration of factors influencing phases of fetal and infant growth beginning with determinants of placental size. Placental weight was related to birth size. Seven percent of the variance in placental weight was explained by a combination of gestation at delivery, maternal size at first prenatal visit, paternal height (all positive), and increasing parity (negative). When centered on birth weight, 41% of the variance in placental weight was explained by birth weight, length of gestation, smoking during pregnancy (all positive), and a female baby (negative). Maternal and paternal stature equally influenced newborn and infant size. Conditional analysis reveals a series of modifiable (parity, length of gestation, and smoking) and nonmodifiable factors at different stages of the growth process.

Background: Being born small for gestational age is associated with later risk factors for cardiovascular disease, such as high blood pressure. Promotion of postnatal growth has been proposed to ameliorate these effects. There is evidence in animals and infants born prematurely, however, that promotion of growth by increased postnatal nutrition increases rather than decreases later cardiovascular risk. We report the long-term impact of growth promotion in term infants born small for gestational age (birth weight <10th percentile)., Methods and Results: Blood pressure was measured at 6 to 8 years in 153 of 299 (51%) of a cohort of children born small for gestational age and randomly assigned at birth to receive either a standard or a nutrient-enriched formula. The enriched formula contained 28% more protein than standard formula and promoted weight gain. Diastolic and mean (but not systolic) blood pressure was significantly lower in children assigned to standard compared with nutrient-enriched formula (unadjusted mean difference for diastolic blood pressure, -3.2 mm Hg; 95% CI, -5.8 to -0.5; P=0.02) independent of potential confounding factors (adjusted difference, -3.5 mm Hg; P=0.01). In observational analyses, faster weight gain in infancy was associated with higher later blood pressure., Conclusions: In the present randomized study targeted to investigate the effect of early nutrition on long-term cardiovascular health, we found that a nutrient-enriched diet increased later blood pressure. These findings support an adverse effect of relative "overnutrition" in infancy on long-term cardiovascular disease risk, have implications for the early origins of cardiovascular disease hypothesis, and do not support the promotion of faster weight gain in infants born small for gestational age.

Background: The Millennium Cohort Study of UK babies born this century obtained maternal report of birth weight and data on the family's characteristics, including parental ethnicity, education, and social circumstances. Parental permission to link babies to their birth registration data provided the opportunity to investigate factors affecting accuracy of maternal recall of birth weight and to determine possible causes of error., Methods: Logistic regression was used to investigate the relationship between maternal factors and recall of birth weight. Numerical and graphical methods were used to identify potential causes for birth weight discrepancies., Results: Data were obtained from the birth registry and Millennium Cohort Study for 11 890 of the 14 294 cohort children born in England and Wales. Weight was reported in imperial units by 84% of mothers and this was more common in younger mothers. Accuracy within 100 g was 92% overall, varying from 94% among British/Irish white mothers to 69-89% for other ethnic groups and was lower among the long-term unemployed and those living in disadvantaged or ethnic wards. Explanations (mostly rounding and transcription errors) were identified for 27% of the discrepancies of 100 g or more. Conclusion Mothers' reports of their infants' birth weight showed high level of agreement with registration data, the mean discrepancy being consistently close to zero. However, the variance of the discrepancy differed according to ethnic group, ward type, and socioeconomic status. These sources of differential variability should be taken into account in analyses using birth weight, and possibly other reported data, from socially mixed populations.

The fetal origins of adult disease hypothesis postulates that the inverse association between birth weight and later adverse outcome reflects fetal programming that increases the risk of later disease. However, low birth weight is associated with catch-up after birth, and weight gain is itself a risk factor for later disease. It is difficult to disentangle the effects on outcome of the size and growth components of weight change through time. This paper presents the life course plot, a device to display both size and growth effects simultaneously. It is based on the multiple-regression analysis of the outcome on the various weights, expressed as z-scores, and the plot displays the coefficients plotted against the corresponding ages of measurement. Examples from Brazil (Pelotas) and the Phillippines (Cebu) relate blood pressure in adolescence to weight through childhood. They show small inverse weight effects in infancy, but early weight is less important than weight and weight gain during adolescence. In addition, birth length in the Cebu study affects the strength of the relationship between weight and blood pressure in adolescence. This suggests a fetal programming effect, with children who were relatively long at birth having a more sensitive relationship between blood pressure and weight at age 15. Whether this is a good or a bad thing is not immediately clear.

Unlabelled: Studies in animals have indicated that cholesterol metabolism is susceptible to manipulation by diet and growth in early life. In humans, low birthweight has been associated with increased risk of coronary heart disease., Aim: To establish whether plasma lipids and indicators of cholesterol absorption, synthesis and breakdown differ in children born preterm and at term., Methods: Plasma total cholesterol, high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, triacylglycerols, apolipoprotein A1, apolipoprotein B, lathosterol (indicator of cholesterol synthesis), campesterol (indicator of cholesterol absorption), 7-alpha hydroxycholesterol (indicator of cholesterol breakdown) were measured in up to 407 children born preterm and 36 children born at term., Results: Children born preterm had lower cholesterol synthesis (p = 0.002) and lower cholesterol breakdown (p < 0.001) than those born at term, but their plasma cholesterol concentration was not significantly different. After adjusting for current size, birthweight and gestational age were significantly related to plasma lathosterol and 7-alpha hydroxycholesterol. However, when both birthweight and gestational age were adjusted, only gestational age remained significant. There were no significant differences in plasma campesterol between the two groups., Conclusion: Being born preterm may have a long-term effect on cholesterol metabolism in children 8-12 y later. Those born prematurely had lower cholesterol synthesis and breakdown, but their plasma cholesterol concentration was similar at this age. These parameters need to be studied in older cohorts.

Background: A high birth weight has been suggested to increase the later risk of obesity, as measured by body mass index, but, paradoxically, to decrease the later propensity to cardiovascular disease. Programming of more lean tissue rather than fat mass by a high birth weight might explain this paradox and also explain the association of birth weight with later body mass index. This concept has been inadequately tested., Objective: The objective was to test the hypothesis that a high birth weight programs a greater proportion of lean mass in children and adolescents., Design: Body fat mass and fat-free mass were assessed by both skinfold-thickness measurement and bioelectrical impedance analysis in adolescents aged 13-16 y (n = 78) who were part of a study that investigated the early origins of cardiovascular disease. Body composition was assessed by dual-energy X-ray absorptiometry in a separate group of younger children., Results: An increase in birth weight of 1 SD was significantly associated with a 0.9-1.4-kg (2-3%) increase in fat-free mass in adolescents but not with an increase in fat mass. This association was independent of age, sex, height, pubertal stage, socioeconomic status, and physical activity. Similar observations were made in younger children., Conclusions: Our data support the hypothesis that fetal growth, measured by birth weight, programs lean mass later in life. Our observations may therefore explain the association of birth weight with body mass index and have implications for the early origins of both obesity and cardiovascular disease.

Catch-up growth in previously growth-restricted children is a suggested risk factor for chronic disease risk. We use data from 2026 Filipino adolescents to identify periods of growth that matter more for risk of high blood pressure (BP). Subjects were drawn from the Cebu Longitudinal Health and Nutrition Survey, which enrolled pregnant women and followed up their offspring through age 14 to 16 years. High BP was defined as the top 10% of residuals from gender-specific regressions of systolic and diastolic BP on age and height. After controlling for birth length, current body mass index, age, and height, the odds of high BP in males were significantly decreased with each kilogram increase in birth weight. The highest odds of elevated BP occurred among males who were relatively thin at birth but relatively heavy as adolescents. Larger weight increments from birth to 2 years decreased the odds of high BP in boys, whereas larger increments from 8 to 11 and 11 to 16 years increased the odds of high BP. Thinness at birth significantly interacted with growth rate after age 8, such that a high rate of weight gain increased risk only among boys who were in the lower two thirds of the body mass index distribution at birth. Results in girls indicated small or no effects of early growth. The synergistic effect on adolescent BP of rapid weight gain from late childhood into adolescence with thinness at birth is further evidence of fetal programming of BP in males and suggests long-term health risks associated with rapid growth, even in the absence of obesity.

Low birth weight, a major cause of infant morbidity and mortality, is caused by different factors in Western and developing-country populations. In addition to differing in terms of ethnicity, maternal size, maternal nutritional status, and disease load, developing-country and Western populations are also characterized by different environmental heat loads. Thermodynamic theory predicts that heat stress is mitigated by reduced size of both mother and offspring, and therefore generates the hypothesis that reduced birth weight may be an adaptation to environmental heat load. The aim of this study was to test the hypothesis that environmental heat load is associated with between-population variability in birth weight. Data on birth weight and thermal environment were obtained from the literature for 140 populations. Further data on several physical, social, and biological confounders were also collated. After adjusting for confounding factors, of which only maternal height and per capita gross domestic product were statistically significant, heat stress showed a significant inverse relationship with birth weight in 108 populations, accounting for an additional 9.6% of the between-population variance. Though based on data collected from more than one source, these results are consistent with the hypothesis that heat stress is inversely associated with birth weight, as previously reported for within-population studies. Further studies are needed to establish to what extent heat stress is a determinant of low birth weight in developing countries., (Copyright 2002 Wiley-Liss, Inc.)

Objective: To test the efficacy in terms of birth weight and infant survival of a diet supplement programme in pregnant African women through a primary healthcare system., Design: 5 year controlled trial of all pregnant women in 28 villages randomised to daily supplementation with high energy groundnut biscuits (4.3 MJ/day) for about 20 weeks before delivery (intervention) or after delivery (control)., Setting: Rural Gambia., Subjects: Chronically undernourished women (twin bearers excluded), yielding 2047 singleton live births and 35 stillbirths., Main Outcome Measures: Birth weight; prevalence of low birth weight (< 2500 g); head circumference; birth length; gestational age; prevalence of stillbirths; neonatal and postneonatal mortality., Results: Supplementation increased weight gain in pregnancy and significantly increased birth weight, particularly during the nutritionally debilitating hungry season (June to October). Weight gain increased by 201 g (P < 0.001) in the hungry season, by 94 g (P < 0.01) in the harvest season (November to May), and by 136 g (P < 0.001) over the whole year. The odds ratio for low birthweight babies in supplemented women was 0.61 (95% confidence interval 0.47 to 0.79, P < 0.001). Head circumference was significantly increased (P < 0.01), but by only 3.1 mm. Birth length and duration of gestation were not affected. Supplementation significantly reduced perinatal mortality: the odds ratio was 0.47 (0.23 to 0.99, P < 0.05) for stillbirths and 0.54 (0.35 to 0.85, P < 0.01) for all deaths in first week of life. Mortality after 7 days was unaffected., Conclusion: Prenatal dietary supplementation reduced retardation in intrauterine growth when effectively targeted at genuinely at-risk mothers. This was associated with a substantial reduction in the prevalence of stillbirths and in early neonatal mortality. The intervention can be successfully delivered through a primary healthcare system.

This study compares how effectively the ponderal index and the body mass index adjust birthweight for length at different gestations, and derives an improved index suitable for all gestations. The study was a cross-sectional survey, in a London teaching hospital, using a total of 999 neonates of 33 weeks gestation or later. Main outcome measures were the ponderal index (birthweight/length3), body mass index (birthweight/length2), and Benn index (birthweight/length(n)), where the length power n varies with gestation and is estimated by log-log regression. Results showed that up to 39 weeks gestation, the ponderal index is uncorrelated with length and so is a good index of birthweight for length. Past 39 weeks gestation, the ponderal index is negatively correlated with length, while the body mass index is uncorrelated, so that the body mass index is better. Neither index is optimal at all gestations. Deriving the Benn index (birthweight/length(n)) for each week of gestation, choosing n to make the index uncorrelated with length, shows that n falls steadily and very significantly (p < 0.0001) with increasing gestation. This in turn means that predicted birthweight for length depends on gestation: for a neonate 48 cm long, predicted birthweight varies from 2485 g at 34 weeks to 3030 g at 43 weeks, a 20% range. However, for a 54 cm long infant, predicted birthweight is the same at all gestations. A Benn index where the value of n changes linearly with gestation is described. We conclude that the ponderal index is not appropriate for measuring intra-uterine malnutrition, as it fails to adjust for length at all gestations. No other index of birthweight/length(n) with constant n is any better, as different gestations require different indices. Birthweight predicted from an infant's length depends on the infant's gestation. If, as Barker proposes, thinness at birth assessed by birthweight for length is used to predict later health status, more account needs to be taken of the complex relationship between birthweight, length and gestation.

The association between birthweight ratio and outcome was investigated in 429 infants born before 31 weeks' gestation. Birthweight ratio was calculated in each case as birth weight divided by mean birth weight for gestation (from reference data). It was shown that a given ratio corresponded to the same birth centile across the gestational age range studied; a ratio of 0.8 corresponding to the 10th centile. There was a linear relationship between birthweight ratio and requirement for mechanical ventilation and postneonatal mortality. Birthweight ratio was also strongly and linearly related to body weight, length, and head circumference at 18 months' corrected age. Overall, there was no association between this ratio and neurodevelopmental outcome to 18 months. However, the subgroup with the largest weights for gestation (birthweight ratio greater than or equal to 1.1), had significantly higher language subscores than all the other children. Our data show that conventional dichotomous categorisation of preterm infants into small or appropriate for gestation is inadequate when exploring the association between size for gestation and outcome.

Birthweight data from 197 rural Gambian women who received an energy-dense prenatal dietary supplement over a 4-y period (net intake = 430 kcal/d) was compared with data from 182 women from 4 baseline years. Preintervention birthweights averaged 2944 +/- 43 (SEM) g when women were in positive energy balance during the dry harvest season (pregnancy weight gain greater than 1200 g/mo). Birthweights decreased to 2808 +/- 41 g (p less than 0.01) in the wet season when food shortages and agricultural work caused negative energy balance (weight gain less than 500 g/mo). There were no detectable secular trends in the baseline data. Supplementation was ineffective during the dry season but highly effective during the wet season: +225 +/- 56 g, p less than 0.001 (unadjusted) or +200 +/- 53 g, p less than 0.001 (adjusted for sex, season, and parity) by between-child multiple regression analysis; +231 +/- 65 g, p less than 0.001 by within-mother analysis. The proportion of low-birthweight babies (less than 2501 g) decreased from 23.7-7.5%, p less than 0.002. The observed threshold effect emphasizes the importance of selective targeting of interventions to truly at-risk groups.

The relationship between birthweight, gestation and obstetric and neonatal course was examined for 444 live births at 25-31 weeks gestation in 5 centres from 1982 to 1984 and comparative data were obtained from 121 infants below 32 weeks born in 1968-1972. The rate of 'interventive' deliveries by elective caesarean section, at this gestation, performed largely for conditions associated with poor intrauterine growth, has risen over 10-fold in the past decade, now accounting for 42% of deliveries at 30 weeks. This may explain in part a secular trend towards reduced birthweight for gestation in preterm infants. Electively delivered infants were significantly lighter than those delivered spontaneously and were responsible for substantial skewing and lowering of overall birthweight centiles. In contrast, the infant's sex, whether or not the infant survived following live birth, and whether gestational age was assessed by maternal dates or by clinical estimation (including ultrasound), all made no significant difference to birthweight centiles. A new birthweight centile chart is presented for infants less than 32 weeks, based only on spontaneous deliveries. This chart differs considerably from those commonly used in Britain and, we suggest, provides a realistic standard for identifying abnormal intrauterine growth.

Data on 1800 term babies, 600 from each of the Chinese, Malay and Indian racial groups, were used to identify the factors affecting birthweight in Singapore. After adjustment for gestation, maternal height and other variables, the mean Indian birthweight was 100 g less than for the Chinese (P less than 0.001), 0.001), while the Malays averaged 33 g less than the Chinese. The shortfall in Indian birthweight is thought to be due, at least partly, to environmental factors.

At Sorrento Maternity Hospital Asian mothers whose babies had grown poorly in utero had anthropometric and biochemical evidence suggesting an inadequate nutritional state. To test this hypothesis further the effect of unselective dietary protein energy supplementation was studied. A total of 153 Asian mothers received one of three supplements from the 18th to 38th weeks of pregnancy: (a) vitamins only--vitamin C 30 mg daily, iron 3 mg daily; (b) energy--42-80 MJ; (10 000-19 000 kcal)/trimester, all from carbohydrate, plus vitamins; (c) protein energy--energy and vitamins as before, but with 5-11% of energy from milk protein. By the 28th week mothers receiving the protein energy supplement had put on more weight and more fat than the vitamin-only group. Neither protein energy nor energy supplementation alone enhanced intrauterine growth. It is concluded that dietary supplementation of all pregnant mothers does not enhance intrauterine growth.

In a cross sectional sample of 655 Glasgow babies the mean birthweight, after adjusting for other factors, of those with unemployed fathers was 150 g less (P less than 0.02) than for babies whose fathers were employed. A longitudinal study of 107 babies from 2 contrasting areas in Glasgow one of which was a socially deprived area was carried out concurrently. The deficit in length of 2.6% for infants from the deprived area at age 12 months was completely explained by adjusting for length at 1 month, father's height, and father's employment status (P less than 0.01). The effect of unemployment on the babies' birthweight was not affected by adjustment for social class. Unemployment may be related to poor infant growth in inner city areas and a national study is needed to see if the recent rise in unemployment has affected this association.

Unselective dietary protein energy supplementation of Asian mothers at Sorrento Maternity Hospital did not enhance intrauterine growth. The effect of selective supplementation was therefore studied. Forty-five mothers who at 28 weeks were known to be nutritionally at risk (triceps increment less than or equal to 20 microns/week between 18 and 28 weeks) received one of three supplements during the third trimester: (a) vitamins only--a multivitamin sachet daily containing vitamins A, B, C, and D; (b) energy--42-125 MJ (10 000-30 000 kcal), all from carbohydrate, plus vitamins; (c) protein energy--energy and vitamins as before, but with 5-10% of energy from milk protein. Eighty-three mothers regarded as adequately nourished at 28 weeks also received one of the three supplements. In the nutritionally at-risk mothers the protein energy supplement was associated with a heavier crude birth weight and heavier weight for gestational age. Supplementation did not lead to improved intrauterine growth in those mothers who were adequately nourished. The differential effect of supplementation depending on the mothers' nutritional state during the second trimester may explain apparently conflicting results of other studies where some have shown a substantial effect of supplementation and others only a small effect. This effect of intervention is further evidence that "poor nutrition" contributes to poor intrauterine growth in selected mothers, even in developed countries.

Gambian women, who show marked seasonal fluctuations in energy balance, were offered a dietary supplement during pregnancy. This resulted in a net energy increment of 431 kcal/day. In the wet season, when the women were normally in marked negative energy balance due to food shortages and a high agricultural work load, the supplementation improved birth-weight by a mean of 224 g and reduced the incidence of low-birth-weight babies (less than 2.5 kg) from 28.2% to 4.7%. In the dry season, when the women were previously in positive energy balance despite an energy intake of only 60% of the recommended dietary allowance, the supplement had no beneficial effect on birth outcome. This threshold effect indicates the need to identify truly at-risk groups for prenatal supplementation programmes in developing countries.

The activity of 81 pregnant, lactating and non-pregnant, non-lactating women in the rural subsistence farming village of Keneba, The Gambia, was measured for 12 months using a combination of 24-hour activity recall and activity diaries. During the course of pregnancy women became gradually less active and in the month before giving birth were 25% less active than non-pregnant, non-lactating women and lactating women when women in the month after birth were excluded. There were striking seasonal changes in activity. During the dry season, from January to April, lactating women were active 55% of the 15-hour working day. At the start of the farming season in June and July this figure increased to 92%. Similar changes were observed in the pregnant women whose activity increased from a mean 50% in April to 83% in June. The period of intense activity coincided with a general shortage of food and increased incidence of disease. The intense activity of pregnant women in the farming season coupled with the low food intakes are most probably the main factors responsible for the striking fall in birth weights observed at this time of the year. Reduced lactational performance was apparent in relation to high activity when it necessitated the mother regularly spending much of the day away from her child. FAO/WHO-recommended energy intakes during pregnancy and lactation are inappropriate for this community.