The association of maternal growth and socio-economic measures with infant birthweight in four ethnic groups

Intergenerational effect of early-life growth on offspring height: Evidence from the Hertfordshire Cohort Study

BACKGROUND

Previous intergenerational (parent to child) and transgenerational (grandparent to grandchild) studies have shown there is a link between parental and offspring birthweight.

OBJECTIVES

The aim was to explore the association between the early-life weight gain of an individual and the adult height of their children and grandchildren.

METHODS

Study participants across three generations of the Hertfordshire Cohort Study (HCS) were included in this study. Health visitors recorded the birthweight (kg) and weight at 1 year (kg) of the original (F0 generation) HCS participants when they were born in Hertfordshire between 1931 and 1939. A conditional infant weight gain score for F0 participants was calculated using birthweight and weight at 1 year, and self-reported height (cm) of their children (F1 generation) and their grandchildren (F2 generation) was obtained from postal questionnaires. Due to the lack of clustering within family lines, linear regression analysis was used to compare intergenerational relationships.

RESULTS

Data were available from 139 F0, 148 F1, and 198 F2 participants. A positive association was found between parental birthweight (F0) and offspring adult height; on average, a 1 kg increase in F0 birthweight was associated with a 2.04 cm increase in F1 adult height (beta 2.04, 95% confidence interval [CI] -0.03, 4.10). A positive association was found between F0 conditional weight gain during the first year of life and offspring (beta 1.53, 95% CI 0.45, 2.62) and grandchild height (beta 1.06, 95% CI 0.03, 2.10). Positive associations were also found between F0 weight at 1 year and offspring (beta 1.83, 95% CI 0.79, 2.87) and grandchild height (beta 0.91, 95% CI -0.10, 1.91).

CONCLUSION

This study demonstrates an association between grandparental weight gain in early life and the heights of their children and grandchildren. The results of these analyses highlight the importance of early-life weight gain on the adult stature of subsequent offspring.

Factors Associated with Low Birth Weight in Indigenous Populations: a systematic review of the world literature

Abstract Objectives: we aimed to identify etiological factors for low birth weight (LBW), prematurity and intrauterine growth restriction (IUGR) in the Indigenous Population. Methods: for this systematic review, publications were searched in Medline/PubMed, Scopus, Web of Science, and Lilacs until April 2018. The description in this review was based on the PRISMA guideline (Study protocol CRD42016051145, registered in the Centre for Reviews and Dissemination at University of York). We included original studies that reported any risk factor for one of the outcomes in the Indigenous Population. Two of the authors searched independently for papers and the disagreements were solved by a third reviewer Results: twenty-four studies were identified, most of them were from the USA, Canada and Australia. The factors associated were similar to the ones observed in the non-indigenous including unfavorable obstetric conditions, maternal malnutrition, smoking, and maternal age at the extremes of childbearing age, besides environmental factors, geographic location, and access to health care in indigenous communities. Conclusions: etiologic factors for LBW in Indigenous Population have been receiving little attention, especially in Latin America. The three outcomes showed common causes related to poverty and limited access to healthcare. New studies should ensure explicit criteria for ethnicity, quality on the information about gestational age, and the investigation on contextual and culture-specific variables.

Low birth weight in Iran: Implications from a systematic review of the literature and meta-analysis in the period 1999-2017

Background: Low birth weight (LBW), a crucial determinant of neonatal complications, represents a major public health concern worldwide. Epidemiological research is of crucial importance for designing and implementing ad hoc interventions for this issue, helping and guiding decision- and policy-makers in each country to prevent the increased prevalence of LBW in infants through estimating the prevalence rate, identifying and controlling major risk factors. The present investigation aimed to systematically assess LBW prevalence rate in Iran and its determinants. Methods: PubMed/Medline via Ovid, Embase, Web of Science and Scopus as well as Magiran, SID and Irandoc were searched from inception until November 2016. Also, the grey literature (via Google Scholar) was mined. The DerSimonian-Laird model was exploited. The I2 and Q-test tests were used to investigate heterogeneity between the studies. Sensitivity and subgroup analyses were performed to ensure the robustness and validity of our findings. Different cumulative meta-analyses were conducted stratifying according to the year of publication and sample size. Any potential bias in publication was assessed carrying out the Egger's test. Results: LBW prevalence rate was estimated to be 8% (95%CI: 7-9) in Iran. Sensitivity analysis confirmed the stability of finding. Studies were cumulated by the year of publication, and the results did not change pre- and post-cumulative meta-analysis. No publication bias could be observed. Conclusion: LBW prevalence rate in Iran is well comparable with the prevalence figures of both developed and developing countries. This could be due to the health reforms implemented in Iran throughout the years.

Maternal pelvic dimensions and neonatal size: Implications for growth plasticity in early life as adaptation

Patterns of fetal growth predict non-communicable disease risk in adult life, but fetal growth variability appears to have a relatively weak association with maternal nutritional dynamics during pregnancy. This challenges the interpretation of fetal growth variability as 'adaptation'. We hypothesized that associations of maternal size and nutritional status with neonatal size are mediated by the dimensions of the maternal pelvis. We analysed data on maternal height, body mass index (BMI) and pelvic dimensions (conjugate, inter-spinous and inter-cristal diameters) and neonatal gestational age, weight, length, thorax girth and head girth (n = 224). Multiple regression analysis was used to identify independent maternal predictors of neonatal size, and the mediating role of neonatal head girth in these associations. Pelvic dimensions displaced maternal BMI as a predictor of birth weight, explaining 11.6% of the variance. Maternal conjugate and inter-spinous diameters predicted neonatal length, thorax girth and head girth, whereas inter-cristal diameter only predicted neonatal length. Associations of pelvic dimensions with birth length, but not birth weight, were mediated by neonatal head girth. Pelvic dimensions predicted neonatal size better than maternal BMI, and these associations were mostly independent of maternal height. Sensitivity of fetal growth to pelvic dimensions reduces the risk of cephalo-pelvic disproportion, potentially a strong selective pressure during secular trends in height. Selection on fetal adaptation to relatively inflexible components of maternal phenotype, rather than directly to external ecological conditions, may help explain high levels of growth plasticity during late fetal life and early infancy.

The New "Obstetrical Dilemma": Stunting, Obesity and the Risk of Obstructed Labour

The "obstetrical dilemma" refers to the tight fit between maternal pelvic dimensions and neonatal size at delivery. Most interest traditionally focused on its generic significance for humans, for example our neonatal altriciality and our complex and lengthy birth process. Across contemporary populations, however, the obstetrical dilemma manifests substantial variability, illustrated by differences in the incidence of cephalo-pelvic disproportion, obstructed labour and cesarean section. Beyond accounting for 12% of maternal mortality worldwide, obstructed labour also imposes a huge burden of maternal morbidity, in particular through debilitating birth injuries. This article explores how the double burden of malnutrition and the global obesity epidemic may be reshaping the obstetrical dilemma. First, short maternal stature increases the risk of obstructed labour, while early age at marriage also risks pregnancy before pelvic growth is completed. Second, maternal obesity increases the risk of macrosomic offspring. In some populations, short maternal stature may also promote the risk of gestational diabetes, another risk factor for macrosomic offspring. These nutritional influences are furthermore sensitive to social values relating to issues such as maternal and child nutrition, gender inequality and age at marriage. Secular trends in maternal obesity are substantially greater than those in adult stature, especially in low- and middle-income countries. The association between the dual burden of malnutrition and the obstetrical dilemma is therefore expected to increase, because the obesity epidemic is emerging faster than stunting is being resolved. However, we currently lack objective population-specific data on the association between maternal obesity and birth injuries. Anat Rec, 300:716-731, 2017. © 2017 Wiley Periodicals, Inc.

Adolescent mothers' anthropometrics and grandmothers' schooling predict infant anthropometrics in Ethiopia, India, Peru, and Vietnam

We investigated intergenerational associations of adolescent mothers' and grandmothers' anthropometrics and schooling with adolescent mothers' offspring's anthropometrics in Ethiopia, India, Peru, and Vietnam. We examined birthweight (n = 283), birthweight Z-score (BWZ), conditional growth in weight-for-age Z-score (cWAZ, residuals from a regression of WAZ at last survey round on BWZ, sex, and age), and height-for-age Z-score (HAZ) of children born to older cohort adolescent girls in the Young Lives study. Our key independent variables were adolescent mothers' body size: HAZ and body-mass-index-for-age Z-score (BMIZ) at age 8, conditional HAZ (cHAZ, residuals from a regression of HAZ at the end of a growth period on prior HAZ, age, and sex), conditional BMIZ growth (cBMIZ, calculated analogously), and grandmaternal BMIZ, HAZ, and schooling. We adjusted for child, maternal, and household characteristics. Adolescent mothers' cHAZ (ages 8-15) predicted birthweight (β = 130 g, 95% confidence interval (CI) 31-228), BWZ (β = 0.31, CI 0.09-0.53), and cWAZ (β = 0.28, CI 0.04-0.51). Adolescent mothers' BMIZ at age 8 predicted birthweight (β = 79 g, CI 16-43) and BWZ (β = 0.22, CI 0.08-0.36). Adolescent mothers' cBMIZ (ages 12-15) predicted child cWAZ and HAZ. Grandmothers' schooling predicted grandchild birthweight (β = 22 g, CI 1-44) and BWZ (β = 0.05, CI 0.01-0.10).

Sex-specific associations of maternal birthweight with offspring birthweight in the Omega study

PURPOSE

We investigated nonlinear and offspring sex-specific associations of maternal birthweight (BW) with offspring BW among participants of the Omega study, a pregnancy cohort.

METHODS

Maternal BW was modeled as a continuous variable, linear spline and binary variable indicating low birthweight (LBW; <2500 vs. ≥2500 grams). Offspring BW was modeled as a continuous and binary variable in regression models. Nonlinearity was assessed using likelihood ratio tests (LRTs) in marginal linear spline models.

RESULTS

For every 100-gram increase of maternal BW, offspring BW increased by 22.29 (95% CI: 17.57, 27.02) or 23.41 (95% CI: 6.87, 39.96) grams among mothers with normal BW or born macrosomic, respectively, but not among LBW mothers (β = -8.61 grams; 95% CI: -22.88, 5.65; LRT P-value = .0005). For every 100-gram increase in maternal BW, BW of male offspring increased 23.47 (95% CI: 16.75, 30.19) or 25.21 (95% CI: 4.35, 46.07) grams among mothers with normal BW or born macrosomic, respectively, whereas it decreased 31.39 grams (95% CI: -51.63, -11.15) among LBW mothers (LRT P-value < .0001). Corresponding increases in BW of female offspring (16-22 grams) did not differ among mothers with LBW, normal BW or macrosomia (LRT P-value = .9163).

CONCLUSIONS

Maternal and offspring BW associations are evident among normal BW and macrosomic mothers. These associations differ by offspring sex.

The magnitude of changes in linear growth within Taiwanese families: intrinsic sex-associated biology, socially mediated behaviors, or both?

OBJECTIVE

This study evaluates competing hypotheses about implications of greater female growth canalization for differences in male and female growth as developmental settings improve.

PARTICIPANTS AND METHODS

Intergenerational declines in gender bias and rapid economic growth in Taiwan permit assessment of the two hypotheses using anthropometric and background information from 107 Taiwanese parents and their young adult offspring. Differences in parents' values were first evaluated across grandfathers' occupational status categories reflecting good to relatively poor early circumstances in the parental generation. The extent of intergenerational change in heights or knee heights within 56 father-son pairs were then compared with those in 51 statistically independent mother-daughter pairs across the same occupational categories using repeated measures analyses.

RESULTS

Change in mean heights and knee heights across grandfathers' occupational categories were noticeably greater for fathers than mothers. Overall, intergenerational gains within families in height and knee height were statistically significant (p < 0.0005) in father-son (3.89 cm; 1.85 cm) and mother-daughter pairs (4.14 cm; 1.67 cm). However, among families where grandfather's occupations were "privileged," father-son pairs are similar in average height (Δ = -0.36 cm) and knee height (Δ = 0.53 cm) while mothers were significantly shorter (Δ = 3.88 cm) with shorter knee heights (Δ = 1.74 cm) than their daughters.

DISCUSSION

The hypothesis that females are inherently less capable of responding to growth promoting characteristics of early environments is not supported. Intergenerational declines in male preference combined with rapid but equitable economic growth better account for intergenerational changes reported.

Birth weight and adult cardiovascular risk factors using multiple birth status as an instrumental variable in the 1958 British Birth Cohort

BACKGROUND

Birth weight is classified as a risk factor for cardiovascular disease by the World Health Organization, but appropriate preventive interventions remain unclear because the observations have not been confirmed in experiments and appear to be contextually specific.

METHODS

Using 9452 participants of the 1958 British Birth Cohort at age 42years in 2000 (58% follow-up), we examined the credibility of multiple birth status as an instrumental variable (IV) for birth weight and, if appropriate, use it to obtain less confounded estimates of the associations of birth weight with cardiovascular disease risk factors including self-reported height, body mass index and hypertension than conventional regression in 2014.

RESULTS

Multiple birth (203 twins and 6 triplets) was associated with older maternal age, but not with paternal occupation or maternal smoking. Multiple births had lower birth weight-for-gestational age z-score. Multiple birth status was not directly associated with height, BMI or hypertension. Using IV estimates birth weight-for-gestational age z-score was not clearly associated with height (0.99cm, 95% confidence interval (CI) -0.27, 2.25), body mass index (BMI) (0.42kg/m(2), 95% CI -0.17, 1.01) or hypertension (risk ratio 0.82, 95% CI 0.54, 1.23) adjusted for maternal age, with a first-stage F statistic of 145.3 from IV analysis.

CONCLUSIONS

Multiple birth status is a credible IV for obtaining a less confounded estimate of the association of birth weight with height, BMI and blood pressure. Such analysis suggests that birth weight may be spuriously related to height, BMI and blood pressure, and thus not an effective target for intervention.

The relationship between preterm birth and underweight in Asian women

Although vast improvements have been made in the survival of preterm infants, the toll of preterm birth (PTB) is particularly severe in Asia, with the Indian subcontinent leading the preterm birth rate. Despite the obesity epidemic, maternal underweight remains a common occurrence in developing countries. An association between maternal underweight and preterm birth has been reported in developed countries. A review of epidemiological studies in Asian women in whom association between maternal body mass index (BMI) and risk of PTB was measured, indicated no significant association between low maternal BMI and preterm birth. A hindrance in comparison of these studies is the use of different cut-off point for BMI in defining maternal underweight. As a commentary on published studies it is proposed that that country-specific BMI cut points should be applied for defining underweight for Asian women for the purpose of evaluating the association between maternal underweight and preterm birth.

Socioeconomic determinants of infant growth: The Perspective Cohort Study of Thai Children

AIM

  The present study is based on the Prospective Cohort Study of Thai Children (PCTC), and focuses on socioeconomic factors including maternal age, maternal education, living with parents, family size, family income, locality, and sex that affect the growth outcomes of infants at 1 year of age.

METHODS

  Data was collected among 3679 pairs of mothers and infants in the PCTC cohort in rural and urban locations during 2001-2002. Data collection was performed by interviewing mothers in their 7th to 8th month of pregnancy using family profile questionnaires. The anthropometric measures including weight, length, and head circumference of the infants were later collected at 1 year of age at home.

RESULTS

  The results show the effects of family socioeconomic status maternal education, living with parents, family size, family income, locality, and sex on their weight (R(2) = 14.2%, P < 0.001) and length (R(2) = 8.7%, P < 0.001) at 1 year of age. The findings suggest that maternal age, maternal education, living with parents, family size, family income, locality, and sex predict infant head circumference (R(2) = 16.8%, P < 0.001) at 1 year of age.

CONCLUSION

  Infants' growth, including weight, height, and head circumference, are affected by family socioeconomic status factors. It is recommended that the effect of maternal age on growth and development of children among those in the PCTC cohort is examined in the future.

Puberty and dispersal in a wild primate population

This article is part of a Special Issue "Puberty and Adolescence". The onset of reproduction is preceded by a host of organismal adjustments and transformations, involving morphological, physiological, and behavioral changes. In highly social mammals, including humans and most nonhuman primates, the timing and nature of maturational processes are affected by the animal's social milieu as well as its ecology. Here, we review a diverse set of findings on how maturation unfolds in wild baboons in the Amboseli basin of southern Kenya, and we place these findings in the context of other reports of maturational processes in primates and other mammals. First, we describe the series of events and processes that signal maturation in female and male baboons. Sex differences in age at both sexual maturity and first reproduction documented for this species are consistent with expectations of life history theory; males mature later than females and exhibit an adolescent growth spurt that is absent or minimal in females. Second, we summarize what we know about sources of variance in the timing of maturational processes including natal dispersal. In Amboseli, individuals in a food-enhanced group mature earlier than their wild-feeding counterparts, and offspring of high-ranking females mature earlier than offspring of low-ranking females. We also report on how genetic admixture, which occurs in Amboseli between two closely related baboon taxa, affects individual maturation schedules.

Association between maternal characteristics and neonatal birth weight in a Korean population living in the Seoul metropolitan area, Korea: a birth cohort study (COCOA)

Previous studies suggest that maternal characteristics may be associated with neonatal outcomes. However, the influence of maternal characteristics on birth weight (BW) has not been adequately determined in Korean populations. We investigated associations between maternal characteristics and BW in a sample of 813 Korean women living in the Seoul metropolitan area, Korea recruited using data from the prospective hospital-based COhort for Childhood Origin of Asthma and allergic diseases (COCOA) between 2007 and 2011. The mean maternal age at delivery was 32.3 ± 3.5 yr and prepregnancy maternal body mass index (BMI) was 20.7 ± 2.5 kg/m(2). The mean BW of infant was 3,196 ± 406 g. The overall prevalence of a maternal history of allergic disease was 32.9% and the overall prevalence of allergic symptoms was 65.1%. In multivariate regression models, prepregnancy maternal BMI and gestational age at delivery were positively and a maternal history of allergic disease and nulliparity were negatively associated with BW (all P < 0.05). Presence of allergic symptoms in the mother was not associated with BW. In conclusion, prepregnancy maternal BMI, gestational age at delivery, a maternal history of allergic disease, and nulliparity may be associated with BW, respectively.

Maternal Prenatal Nutrition and Health in Grandchildren and Subsequent Generations

This review focuses on how maternal prenatal nutritional states may affect the health of grandchildren and later generations. We first summarize the limited current data in human populations relating to the potential transmission of phenotypes across multiple generations that result from the nutritional experience of a pregnant woman. We then discuss findings from other species, especially mammals, that provide important clues as to whether, and if so how, such transmission could occur in humans. Finally, we consider how studies of human populations could be best designed to detect transmission across multiple generations. We argue that just as epidemiologists embraced a life-course perspective to human health and disease in the twentieth century, we must now seek to better understand how health and disease could be shaped across multiple generations.

Re-examining heritability: genetics, life history and plasticity

Human life-history traits (growth, maturation, nutritional status) are increasingly associated with risk of chronic degenerative disease. Twin studies suggest high heritability of such traits; however, although sophisticated approaches have identified genetic variation underlying a proportion of this heritability, studies also increasingly demonstrate significant plasticity, and many life-history traits are able to change by one standard deviation (SD) over 3-6 generations. Developments in our understanding of the contributions of genetics and plasticity to human life history are likely to improve understanding of the growing burden of chronic diseases. We argue that a life-history approach to understanding variation in the human phenotype must integrate these two risk components, and highlight the important contribution of plasticity to changes in disease prevalence.

The role of maternal early-life and later-life risk factors on offspring low birth weight: findings from a three-generational study

PURPOSE

This study examined three research questions: (1) Is there an association between maternal early-life economic disadvantage and the birth weight of later-born offspring? (2) Is there an association between maternal abuse in childhood and the birth weight of later-born offspring? (3) To what extent are these early-life risks mediated through adolescent and adult substance use, mental and physical health status, and adult socioeconomic status (SES)?

METHODS

Analyses used structural equation modeling to examine data from two longitudinal studies, which included three generations. The first generation (G1) and the second generation (G2) were enrolled in the Seattle Social Development Project (SSDP), and the third generation (G3) was enrolled in the SSDP Intergenerational Project. Data for the study (N = 136) focused on (G2) mothers enrolled in the SSDP and their children (G3).

RESULTS

Analyses revealed that G2 low childhood SES predicted G3 offspring birth weight. Early childhood abuse among G2 respondents predicted G3 offspring birth weight through a mediated pathway including G2 adolescent substance use and G2 prenatal substance use. Birth weight was unrelated to maternal adult SES, depression, or obesity.

CONCLUSIONS

To our knowledge, this is the first study to identify the effect of maternal early-life risks of low childhood SES and child maltreatment on later-born offspring birth weight. These findings have far-reaching effects on the cumulative risk associated with early-life economic disadvantage and childhood maltreatment. Such findings encourage policies and interventions that enhance child health at birth by taking the mother's own early-life and development into account.

Intergenerational correlations in size at birth and the contribution of environmental factors: The Uppsala Birth Cohort Multigenerational Study, Sweden, 1915-2002

Sizes at birth of parents and their children are known to be correlated, reflecting in part the influence of fetal and maternal genes. Sociodemographic factors, regarded as aspects of the shared environment across generations, would also be expected to contribute, but evidence is limited. In the present study, the authors aimed to quantify the role of the shared environment in explaining intergenerational correlations in birth weight and length by using data across 3 consecutive generations from the Uppsala Birth Cohort Multigenerational Study in Uppsala, Sweden. That study included birth and sociodemographic data on 7,657 singletons born in Uppsala in 1915-1929 (generation 1) and their grandchildren (generation 3). Standard regression and biometric models were used to study the correlations in size at birth of generation 1-generation 3 pairs. The data showed stronger correlations in maternal pairs than in paternal pairs for birth weight (0.125 vs. 0.096, P = 0.02) but not for birth length (0.097 vs. 0.093, P = 0.77). These correlations were not reduced by adjustment for sociodemographic factors in regression models. In contrast, significant shared-environment contributions to the intergenerational correlations were identified in biometric models, averaging 14% for both birth measures. These models assumed a common latent factor for the sociodemographic variables. The present results show that the shared environment moderately but significantly contributes to intergenerational correlations.

Energy intake during pregnancy in relation to offspring gender by maternal height

Male newborns are somewhat heavier than female ones and it has been reported, in a Caucasian population, that mothers carrying boys have higher energy intake during pregnancy compared to those carrying girls. In the context of a prospective study comprising 150 Caucasian women in Boston, USA and 243 Asian women in Shanghai China, energy intake at the second trimester of pregnancy was estimated based on center-specific food frequency questionnaires. There was a significant interaction (P = 0.01) of maternal height with offspring gender with respect to maternal daily energy intake. Among taller women, male gender of the offspring was associated with higher maternal energy intake (difference 341 kcal/day, 95% Confidence Interval 77-604; P = 0.01), whereas among shorter women, no significant association existed between offspring gender and maternal daily energy intake (difference -213 kcal/day, 95% Confidence Interval -479 to 54; P = 0.12). Our findings indicate that the higher somatic growth potential of boys in intrauterine life is realized only when there are no constrains imposed by maternal anthropometry and it is, then, associated with higher maternal energy intake during pregnancy.

Review and hypothesis: syndromes with severe intrauterine growth restriction and very short stature--are they related to the epigenetic mechanism(s) of fetal survival involved in the developmental origins of adult health and disease?

Diagnosing the specific type of severe intrauterine growth restriction (IUGR) that also has post-birth growth restriction is often difficult. Eight relatively common syndromes are discussed identifying their unique distinguishing features, overlapping features, and those features common to all eight syndromes. Many of these signs take a few years to develop and the lifetime natural history of the disorders has not yet been completely clarified. The theory behind developmental origins of adult health and disease suggests that there are mammalian epigenetic fetal survival mechanisms that downregulate fetal growth, both in order for the fetus to survive until birth and to prepare it for a restricted extra-uterine environment, and that these mechanisms have long lasting effects on the adult health of the individual. Silver-Russell syndrome phenotype has recently been recognized to be related to imprinting/methylation defects. Perhaps all eight syndromes, including those with single gene mutation origin, involve the mammalian mechanism(s) of fetal survival downsizing. Insights into those mechanisms should provide avenues to understanding the natural history, the heterogeneity and possible therapy not only for these eight syndromes, but for the common adult diseases with which IUGR is associated.

Maternal capital and the metabolic ghetto: An evolutionary perspective on the transgenerational basis of health inequalities

There is particular interest in understanding socioeconomic and ethnic variability in health status. The developmental origins of disease hypothesis emphasize the importance of growth patterns across the life-course in relation to noncommunicable disease risk. The physiological components of cardiovascular risk, collectively termed the metabolic syndrome, derive in part from a disparity between the homeostatic "metabolic capacity" of vital organs and the "metabolic load" induced by large tissue masses, a rich diet and sedentary behavior. From an evolutionary perspective, the risk of such disparity is decreased by maternal physiology regulating offspring growth trajectory during gestation and lactation. Maternal capital, defined as phenotypic resources enabling investment in the offspring, allows effective buffering of the offspring from nutritional perturbations and represents the environmental niche initially occupied by the offspring. Offspring growth patterns are sensitive to the magnitude of maternal capital during early windows of plasticity. Offspring life-history strategy can then respond adaptively to further factors across the life-course, but only within the context of this initial maternal influence on growth. Maternal somatic capital is primarily gained or lost across generations, through variable rates of fetal and infant growth. I argue that the poor nutritional experience of populations subjected to colonialism resulted in a systematic loss of maternal capital, reflected in downward secular trends in stature. Accelerating the recovery of somatic capital within generations overloads metabolic capacity and exacerbates cardiovascular risk, reflected in increased disease rates in urbanizing and emigrant populations. Public health policies need to benefit metabolic capacity without exacerbating metabolic load.

Intergenerational effect of weight gain in childhood on offspring birthweight

Background Some studies suggest that weight gain in childhood may increase the risk of chronic diseases in adulthood, and recent studies have noticed that the timing of weight gain may be related to its long-term consequence. However, weight gain in childhood has clear short-term benefits, and the literature on the pro and cons of weight gain in childhood is limited.

Methods In 1982, all 5914 hospital births (over 99% of all deliveries) occurring in Pelotas, Southern Brazil, were identified and studied prospectively on several occasions. In 2004–05, we attempted to trace the whole cohort and information on offspring birthweight was collected. Conditional growth modelling was used to assess the association between offspring birthweight and weight gain from birth to 20 months, and from 20 to 42 months.

Results In 2004–05, we interviewed 4297 subjects, with a follow-up rate of 77.4%. This manuscript includes data from 848 women who had already delivered a child and 525 men who were fathers at the mean age of 23 years. Maternal birthweight, weight and length for age Z-score at 20 months of age were positively associated with next-generation birthweight, whereas paternal variables were not related to the outcome. Conditional growth modelling analyses showed that women whose weight gain in the first 20 months of life was faster than predicted had heavier babies, whereas paternal weight gain was not associated. The association was strongest for mothers whose birthweight for gestational age was in the lowest tertile.

Conclusion Maternal, but not paternal birthweight and weight gain in early childhood are positively associated with next-generation birthweight.

Short stature of mothers from an area endemic for undernutrition is associated with obesity, hypertension and stunted children: a population-based study in the semi-arid region of Alagoas, Northeast Brazil

The objectives of the study were to investigate whether the health conditions of mothers with short stature differed from those with normal stature, and to establish if these aspects were associated with the health of the offspring. Data relating to health and socio-economic, demographic and anthropometric conditions were collected from a probabilistic sample population consisting of 1180 mothers and 1511 children ( < 10 years) living in the semi-arid region of the State of Alagoas, Brazil. Mothers were categorised according to stature, with those in the 1st quartile being defined as of short stature and those in the 4th quartile being defined as of normal stature and serving as a reference for the comparison of variables of interest. Following verification that maternal stature fulfilled parametric assumptions, its associations with the other variables were determined by calculating Pearson correlation coefficients. After excluding strongly self-correlated variables (r ≥ 0·70), the remaining variables were analysed by multiple linear regression. The results showed that low maternal stature was independently associated with obesity (percentage body fat ≥ 30; P = 0·045), abdominal adiposity (waist:hip ratio ≥ 0·85; P = 0·007) and high systolic blood pressure ( ≥ 140 mmHg; P = 0·006). Short maternal stature was associated with low birth weight ( < 3000 g; P = 0·01) and stunting (height-for-age Z score < − 2; P = 0·019) in the offspring. Thus, in the semi-arid region of Alagoas, women of short stature presented a higher prevalence of chronic degenerative diseases and produced less healthy children than women of normal stature.

The biology of the colonizing ape

Hominin evolutionary history is characterized by regular dispersals, cycles of colonization, and entry into novel environments. This article considers the relationship between such colonizing capacity and hominin biology. In general, colonizing strategy favors rapid rates of reproduction and generalized rather than specialized biology. Physiological viability across diverse environments favors a high degree of phenotypic plasticity, which buffers the genome from selective pressures. Colonizing also favors the capacity to access and process information about environmental variability. We propose that early hominin adaptive radiations were based upon the development of such capacities as adaptations to unstable Pliocene environments. These components came together, along with fundamental changes in morphology, behavior, and cognition in the genus Homo, who exploited them in subsequent wider dispersals. Middle Pleistocene hominins and modern humans also show development of further traits, which correspond with successful probing of, and dispersals into, stressful environments. These traits have their precursors in primate or ape biology, but have become more pronounced during hominin evolution. First, short interbirth intervals and slow childhood growth allow human females to provision several offspring simultaneously, increasing the rate of reproduction in favorable conditions. This allows rapid recovery from population crashes, or rapid population growth in new habitats. Second, despite high geographical phenotypic variability, humans have high genetic unity. This is achieved by a variety of levels of plasticity, including physiology, behavior, and technology, which reduce the need to commit to genetic adaptation. Hominin behavior may increasingly have shaped both the ecological niches occupied and the selective pressures acting back on the genome. Such selective pressures may have been exacerbated by population dynamics, predicted to both derive from, and favor, the colonizing strategy. Exposure to ecological variability is likely to have generated particular selective pressures on female biology, favoring increasing steering of offspring ontogeny by maternal phenotype. We propose that the concept of hominins as "colonizing apes" offers a novel unified model for interpreting the suite of traits characteristic of our genus.

Maternal birthweight and outcome of twin pregnancy

There is evidence from singletons that maternal birthweight is positively related to offspring gestational length and birthweight, and some evidence of an inverse relationship with preterm birth. Among twins very preterm birth is the major cause of neonatal mortality and of immediate and later morbidity, including neurodevelopmental impairment. We hypothesised that the relationship between maternal birthweight and gestational length would be more evident in twin than in singleton pregnancies, as there is more variation in gestation in the former. Among 131 singleton mothers carrying twins, there was weak evidence of a positive relationship between maternal birthweight and twin gestational length (+0.6 weeks [95% CI -0.05, +1.3] per kg increase in maternal birthweight, but stronger evidence among 56 of these who went into labour spontaneously (+1.9 weeks [+0.7, +3.1], P = 0.003 for interaction). In the latter group we estimated that the odds of very preterm birth (at <32 weeks) were reduced by 50% [95% CI 10%, 82%] per 250 g increase in maternal birthweight. In the whole cohort, and in this subgroup, maternal birthweight was strongly positively related to both twin offspring total birthweight and total placental weight. Our data, consistent with intergenerational programming of early development, suggest the possibility of a stronger and more clinically relevant association among twins than among singletons. Nevertheless, our sample size was modest and this finding needs to be confirmed in a larger cohort.

Pre-pregnancy body mass index, gestational weight gain, and other maternal characteristics in relation to infant birth weight

OBJECTIVES

Infant birth weight is influenced by modifiable maternal pre-pregnancy behaviors and characteristics. We evaluated the relationship among pre-pregnancy body mass index (BMI), gestational weight gain, and infant birth weight, in a prospective cohort study.

METHODS

Women were enrolled at < or =20 weeks gestation, completed in-person interviews and had their medical records reviewed after delivery. Infant birth weight was first analyzed as a continuous variable, and then grouped into Low birth weight (LBW) (<2,500 g), normal birth weight (2,500-3,999 g), and macrosomia (> or =4,000 g) in categorical analysis. Pre-pregnancy BMI and gestational weight gain were categorized based on Institute of Medicine BMI groups and gestational weight gain guidelines. Associations among infant birth weight and pre-pregnancy BMI, gestational weight gain, and other factors were evaluated using multivariate regression. Risk ratios were estimated using generalized linear modeling procedures.

RESULTS

Pre-pregnancy BMI was independently and positively associated with infant birth weight (beta = 44.7, P = 0.001) after adjusting for confounders, in a quadratic model. Gestational weight gain was positively associated with infant birth weight (beta = 19.5, P < 0.001). Lower infant birth weight was associated with preterm birth (beta = -965.4, P < 0.001), nulliparity (beta = -48.6, P = 0.015), and female babies (beta = -168.7, P < 0.001). Less than median gestational weight gain was associated with twice the risk of LBW (RR = 2.04, 95% CI 1.34-3.11). Risk of macrosomia increased with increasing pre-pregnancy BMI and gestational weight gain (P for linear trend <0.001).

CONCLUSIONS

These findings support the need to balance pre-pregnancy weight and gestational weight gain against the risk of LBW and macrosomia among lean and obese women, respectively.

The thrifty phenotype as an adaptive maternal effect

Human diseases in adulthood are increasingly associated with growth patterns in early life, implicating early-life nutrition as the underlying mechanism. The thrifty phenotype hypothesis proposed that early-life metabolic adaptations promote survival, with the developing organism responding to cues of environmental quality by selecting an appropriate trajectory of growth. Recently, some authors have proposed that the thrifty phenotype is also adaptive in the longer-term, by preparing the organism for its likely adult environment. However, windows of plasticity close early during human development, and subsequent environmental changes may result in the selected trajectory becoming inappropriate, leading to adverse effects on health. This paradox generates uncertainty as to whether the thrifty phenotype is indeed adaptive for the offspring in humans. The thrifty phenotype should not be considered a dichotomous concept, rather it refers to the capacity of all offspring to respond to environmental information during early ontogenetic development. This article argues that the thrifty phenotype is the consequence of three different adaptive processes - niche construction, maternal effects, and developmental plasticity - all of which in humans are influenced by our large brains. While developmental plasticity represents an adaptation by the offspring, both niche construction and parental effects are subject to selection on parental rather than offspring fitness. The three processes also operate at different paces. Human offspring do not become net calories-producers until around 18 years of age, such that the high energy costs of the human brain are paid primarily by the mother, even after weaning. The evolutionary expansion of human brain volume occurred in environments characterised by high volatility, inducing strong selective pressure on maternal capacity to provision multiple offspring simultaneously. The thrifty phenotype is therefore best considered as a manipulation of offspring phenotype for the benefit of maternal fitness. The information that enters offspring phenotype during early development does not predict the likely future environment of the offspring, but rather reflects the mother's own developmental experience and the quality of the environment during her own maturation. Offspring growth trajectory thus becomes aligned with long-term maternal capacity to provision. In contemporary populations, the sensitivity of offspring development to maternal phenotype exposes the offspring to adverse effects, through four distinct pathways. The offspring may be exposed to (1) poor maternal metabolic control (e.g. gestational diabetes), (2) maternally derived toxins (e.g. maternal smoking), or (3) low maternal social status (e.g. small size). Adverse consequences of these effects may then be exacerbated by (4) exposure either to the "toxic" western environment in postnatal life, in which diet and physical activity levels are mismatched with metabolic experience in utero, or at the other extreme to famine. The rapid emergence of the epidemic of the metabolic syndrome in the 20th Century reflects the rapid acceleration in the pace of niche construction relative to the slower physiological combination of developmental plasticity and parental effects.

Intergenerational effects of preterm birth and reduced intrauterine growth: a population-based study of Swedish mother-offspring pairs

OBJECTIVE

To estimate the intergenerational effects of preterm birth and reduced intrauterine growth.

DESIGN

Population-based cohort study.

SETTINGS

Mother-first-born offspring pairs recorded in the Swedish Medical Birth Registry.

POPULATION

Children born before 2001 to 38 720 women born in 1973-75.

METHODS

The relationships between the mother's and the child's birth characteristics were estimated using logistic regression analysis. Adjustments were made for smoking habits, body mass index (BMI), and current and childhood socio-economic conditions. Analyses were performed on all mother-offspring pairs and on the pairs for which information on neither of the included background variables was missing (n= 24 520).

MAIN OUTCOME MEASURES

Preterm birth (<37 weeks of gestation) and small for gestational age (SGA) (<-2 SD of the Swedish standard).

RESULTS

Mothers who themselves had been born preterm were not significantly more likely to deliver their own children preterm, compared with those who had been born at term (adjusted OR 1.24, 95% CI 0.95-1.62). Also, preterm birth in the mothers did not influence the occurrence of SGA in the children. However, the odds ratio for giving birth to SGA and preterm children, respectively, was higher among SGA mothers (OR 2.68, 95% CI 2.11-3.41 and OR 1.30, 95% CI 1.05-1.61). Mothers whose intrauterine growth was moderately reduced but who did not meet the criterion of being born SGA were also at higher risk of giving birth to both preterm and SGA children, respectively.

CONCLUSIONS

The present study showed evidence of intergenerational effects of reduced intrauterine growth even when socio-economic factors as well as BMI and smoking were adjusted for. There was, however, no consistent intergenerational effect of preterm birth.

The association of grandmaternal and maternal factors with maternal adult stature

BACKGROUND

Stature is an important determinant of several reproductive and non-reproductive health problems. Documentation of secular trends in stature has been based primarily on cross-sectional studies of special populations, primarily of men. The objective of this study is to determine how growth and socio-economic status (SES) factors relate to stature changes among lineal female relatives, maternal grandmothers to mothers.

METHODS

The study base was derived from a population-based intergenerational cohort which linked several statewide databases to data from the mothers' own birth certificates: the Washington State Intergenerational Cohort. Mothers in these ethnic groups were separately studied: non-Hispanic Whites, African Americans, Native Americans, Hispanics. We generated simple, partial, and multiple correlation coefficients to investigate the association between stature and other growth and SES factors.

RESULTS

A mother's stature is determined partly by her own mother's stature and partly by her birthweight. These two measures are individually stronger predictors of stature than are several available SES factors considered in combination-grandmother's age, parity, marital status, and mother's age. The maximal multiple correlation models yielded R2 values from 18% to 28%.

CONCLUSIONS

Growth measures are stronger predictors of intergenerational changes in stature than are the several available socio-economic factors. However, socio-economic factors are partly responsible for the level of achieved prenatal and postnatal growth. Since grandmother's stature is a determinant of mother's birthweight, which in turn is a determinant of infant birthweight, some environmentally influenced determinants of some birth outcomes are already established before a prospective mother is conceived or born.