Nutrition in pregnancy and the concentrations of proinsulin, 32-33 split proinsulin, insulin, and C-peptide in cord plasma

Nausea, vomiting and conflict in pregnancy: The adaptive significance of Growth-Differentiation Factor 15

Nausea and vomiting in pregnancy (NVP) is heritable, common and aversive, and its extreme, hyperemesis gravidarum (HG), can be highly deleterious to the mother and fetus. Recent influential studies have demonstrated that HG is caused predominantly by high levels of Growth-Differentiation Factor 15 (GDF15), a hormone produced by the placenta in substantial amounts. This work has led to calls for therapeutic modulation of this hormone to reduce GDF15 levels and ameliorate HG risk. I describe three main lines of evidence relevant to the hypothesis that GDF15 production is typically adaptive for the fetus, in the context of enhanced placental invasion, reduced rates of miscarriage and preterm birth and higher birth weight. These considerations highlight the medical implications of maternal-fetal conflict, in the context of tradeoffs between aversive symptoms during gestation, rare disorders of pregnancy with major adverse effects and moderate fitness-enhancing benefits to fetuses.

The Role of Maternal Dietary Proteins in Development of Metabolic Syndrome in Offspring

The prevalence of metabolic syndrome and obesity has been increasing. Pre-natal environment has been suggested as a factor influencing the risk of metabolic syndrome in adulthood. Both observational and experimental studies showed that maternal diet is a major modifier of the development of regulatory systems in the offspring in utero and post-natally. Both protein content and source in maternal diet influence pre- and early post-natal development. High and low protein dams’ diets have detrimental effect on body weight, blood pressure191 and metabolic and intake regulatory systems in the offspring. Moreover, the role of the source of protein in a nutritionally adequate maternal diet in programming of food intake regulatory system, body weight, glucose metabolism and blood pressure in offspring is studied. However, underlying mechanisms are still elusive. The purpose of this review is to examine the current literature related to the role of proteins in maternal diets in development of characteristics of the metabolic syndrome in offspring.

Ten putative contributors to the obesity epidemic

The obesity epidemic is a global issue and shows no signs of abating, while the cause of this epidemic remains unclear. Marketing practices of energy-dense foods and institutionally-driven declines in physical activity are the alleged perpetrators for the epidemic, despite a lack of solid evidence to demonstrate their causal role. While both may contribute to obesity, we call attention to their unquestioned dominance in program funding and public efforts to reduce obesity, and propose several alternative putative contributors that would benefit from equal consideration and attention. Evidence for microorganisms, epigenetics, increasing maternal age, greater fecundity among people with higher adiposity, assortative mating, sleep debt, endocrine disruptors, pharmaceutical iatrogenesis, reduction in variability of ambient temperatures, and intrauterine and intergenerational effects as contributing factors to the obesity epidemic are reviewed herein. While the evidence is strong for some contributors such as pharmaceutical-induced weight gain, it is still emerging for other reviewed factors. Considering the role of such putative etiological factors of obesity may lead to comprehensive, cause specific, and effective strategies for prevention and treatment of this global epidemic.

Measurement of cord insulin and insulin-related peptides suggests that girls are more insulin resistant than boys at birth

OBJECTIVE

We aimed to examine sex differences in insulin and insulin propeptide concentrations at birth using validated cord blood collection.

RESEARCH DESIGN AND METHODS

We tested the impact on insulin and insulin propeptides of taking 13 cord blood samples in heparin and EDTA and then centrifuging and separating plasma after 1, 2, 24, or 48 h at room temperature (heparin) or 4 degrees C (EDTA). Cord plasma insulin and insulin propeptides concentrations were measured in 440 babies and correlated with offspring anthropometry measured at birth.

RESULTS

Cord insulin concentrations significantly decreased (74% those at baseline by 24 h; P = 0.01) in the samples taken in heparin and stored at room temperature, but those taken on EDTA and refrigerated remained stable for up to 48 h. Insulin propeptides were stable in both. Cord plasma insulin and insulin propeptides measured in EDTA were related to all measures of birth size and maternal glycemia and BMI (r > 0.11; P < 0.03 for all) and were higher in those delivered via caesarean section. Girls were lighter (3,497 vs. 3,608 g; P = 0.01) but had higher cord insulin (46.7 vs. 41.2 pmol/l; P = 0.031), total proinsulin (34.1 vs. 25.8 pmol/l; P < 0.001), and intact proinsulin (9.5 vs. 8.3 pmol/l; P = 0.004) concentrations than boys; this was further confirmed when cord insulin concentrations of boys and girls were compared after pair matching for birth weight (insulin 49.7 vs. 42.1 pmol/l; P = 0.004).

CONCLUSIONS

When using appropriate sample collection methods, female newborns have higher insulin concentrations than male newborns, despite being smaller, suggesting intrinsic insulin resistance in girls.

Maternal size in pregnancy and body composition in children

CONTEXT

Evidence suggests that babies' fat mass at birth is greater if their mothers were themselves fatter during pregnancy, but it is unclear whether this association persists into childhood.

OBJECTIVE

Our objective was to examine the relation between maternal size in pregnancy, early growth and body composition in children.

DESIGN AND SETTING

We conducted a prospective cohort study in Southampton, United Kingdom.

PARTICIPANTS

Participants included 216 9-yr-old children whose mothers had participated in a study of nutrition during pregnancy.

MAIN OUTCOME MEASURES

Fat mass and lean mass were measured by dual-energy x-ray absorptiometry and adjusted for height (fat mass index and lean mass index).

RESULTS

Fat mass index at age 9 yr was greater in children whose mothers had a larger mid-upper arm circumference in late pregnancy or a higher prepregnant body mass index. For 1 sd increase in maternal mid-upper arm circumference in late pregnancy, fat mass index rose by 0.26 [95% confidence interval (CI) 0.06-0.46] sd in boys and by 0.44 (95% CI 0.31-0.57) sd in girls. For 1 sd increase in maternal prepregnant BMI, fat mass index rose by 0.26 (95% CI 0.04-0.48) sd in boys and by 0.42 (95% CI 0.29-0.56) sd in girls.

CONCLUSIONS

Mothers with a higher prepregnant body mass index or a larger mid-upper arm circumference during pregnancy tend to have children with greater adiposity at age 9. The extent to which this is attributable to genetic factors, the influence of maternal lifestyle on that of her child, or maternal adiposity acting specifically during pregnancy on the child's fat mass cannot be determined in this study.

The gender insulin hypothesis: why girls are born lighter than boys, and the implications for insulin resistance

Girls are born lighter than boys. The consistency of this observation across different populations is striking, suggesting that it may have fundamental significance for those conditions linked with lower birth weight, such as diabetes. Previous hypotheses relating low birth weight to subsequent diabetes have addressed differences in insulin resistance within the sexes, not between them. Here, we propose that gender-specific genes affecting insulin sensitivity are responsible for the gender difference in birth weight--the genetically more insulin resistant female fetus is less responsive to the trophic effects of insulin and is therefore smaller. These genes also render female subjects more susceptible to diabetes, explaining why reports of type 2 diabetes (T2D) in younger populations show a female preponderance. Consistent with our proposal, concentrations of insulin and/or its propeptides are higher at birth in female populations and they are intrinsically more insulin resistant throughout life, with attendant impact on their metabolism, and the regressions describing the relationship between insulin resistance and adiposity in female and male subjects have similar gradients, but different constants. These gender-specific genes have a demonstrable impact on fetal growth and insulin resistance. Diabetes and cardiovascular disease are thought to be driven by insulin resistance, and the observations reported here may help to focus the search for genes that control it.

Paternal insulin resistance and its association with umbilical cord insulin concentrations

AIMS/HYPOTHESIS

Fetal growth is influenced by genetic factors as well as the intra-uterine environment. We hypothesised that some genetic factors may alter fetal insulin secretion and insulin action.

SUBJECTS, MATERIALS AND METHODS

To assess this, we analysed plasma insulin concentration in umbilical cord blood from 644 normal, term, UK Caucasian deliveries from the Exeter Family Study of Childhood Health. We tested for associations between cord insulin and each of parental anthropometry, fasting glucose, insulin and lipids.

RESULTS

As expected, cord insulin concentrations correlated with all measures of birth size (weight, length, head and arm circumferences, sum of skinfold thicknesses, ponderal index: r=0.16-0.4, p<0.01 for all) and maternal BMI (r=0.11, p=0.005), maternal glucose (r=0.25, p<0.001) and maternal insulin resistance (r=0.23, p<0.001). Paternal fasting insulin and insulin resistance were correlated with cord insulin (r=0.15, p=0.006; r=0.13, p=0.001, respectively), and this was independent of paternal BMI. Multiple linear regression analysis revealed paternal insulin resistance to be a predictor of cord insulin concentrations, independently of maternal factors.

CONCLUSION

Our results show an independent relationship between paternal insulin resistance and cord insulin concentrations. This is consistent with heritability of insulin resistance from father to offspring and a compensatory increase in fetal insulin secretion, the latter occurring pre-natally before the homeostatic feedback loop between glucose and insulin is established.

Effect of Interleukin-10 Null Mutation on Maternal Immune Response and Reproductive Outcome in Mice1

Interleukin-10 (IL-10) is an anti-inflammatory and immune-deviating cytokine expressed in the endometrium and placenta. IL-10 null mutant (IL-10-/-) mice have been employed to examine the role of IL-10 in regulating immune events in early pregnancy and its significance in implantation and pregnancy success. The inflammatory response elicited in endometrial tissue by insemination was amplified in IL-10-/- mice, with a 66% increase in leukocytes in the endometrial stroma on Day 3 of pregnancy. Despite this, no evidence of abnormal type 1/type 2 skewing was seen in T-lymphocytes from lymph nodes draining the uterus. On Day 18 of gestation, IL-10-/- females mated with IL-10-/- males had 15% more implantation sites and 27% more viable fetuses than pregnant wild-type (IL-10+/+) mice. Placental weight was unaffected, but fetal weight and the fetal:placental weight ratio were higher in IL-10-/- pregnancies. Similar data were obtained in allogeneic pregnancies when IL-10-/- females were mated with major-histocompatibility complex (MHC) disparate IL-10-/- males. Pups delivered by IL-10-/- mothers had increased birth weight and followed an altered growth trajectory, with growth impairment evident from early postnatal life into adulthood, which was reflected in alterations in body composition at 14 wk of age. This study shows that although IL-10 is not essential for maternal immune tolerance or successful pregnancy irrespective of MHC disparity in the fetus, maternal IL-10 is a determinant of growth trajectory in progeny in utero and after birth.

The malnourished baby and infant

The growth of a baby is constrained by the nutrients and oxygen it receives from the mother. A mother's ability to nourish her baby is established during her own fetal life and by her nutritional experiences in childhood and adolescence, which determine her body size, composition and metabolism. Mother's diet in pregnancy has little effect on the baby's size at birth, but nevertheless programmes the baby. The fetus adapts to undernutrition by changing its metabolism, altering its production of hormones and the sensitivity of tissues to them, redistributing its blood flow, and slowing its growth rate. In some circumstances, the placenta may enlarge. Adaptations to undernutrition that occur during development permanently alter the structure and function of the body.

Intra-uterine programming of the endocrine pancreas

In altricial species such as the rat and mouse, there is good evidence for the intra-uterine programming of the endocrine pancreas. Changes in the intra-uterine nutritional environment cause alterations in the structure and function of the islets which have life-long effects and predispose the animal to glucose intolerance and diabetes in later life. In rodents, the islets develop relatively late in gestation and undergo substantial remodelling in the period immediately after birth. Hence, the critical window for islet development in these animals is short and readily accessible for experimental manipulation. The short life-span of these species also means that elderly animals can be studied within a reasonable time frame. In precocious species, such as guinea pigs and farm animals, intra-uterine programming of the endocrine pancreas is less well established. In part, this may be due to difficulties in identifying the critical window for development as islet formation and remodelling begin at an earlier stage of gestation and continue for longer after birth. The long life-span of these animals and the relative insulin resistance of adult ruminants compared to other species also make it difficult to establish whether fetal changes in islet development have long-term consequences. In the human, the main phase of islet development occurs during the second trimester, although remodelling occurs throughout late gestation and early childhood. There is, therefore, a relatively long period in which early changes in islet development could be reversed or ameliorated in the human. Although the human epidemiological observations suggest that the fetal origin of adult glucose intolerance is due primarily to changes in insulin sensitivity rather than to defective insulin secretion, subtle changes in islet morphology and function sustained in utero may well contribute to the increased susceptibility to type 2 diabetes observed in adults who were growth-retarded in utero.

Insulin resistance in short children with intrauterine growth retardation

Scientific evidence is accumulating for an association between intrauterine growth retardation (IUGR) and an increased risk of developing adult degenerative diseases, such as essential hypertension, non-insulin-dependent diabetes mellitus and ischaemic heart disease. A possible underlying mechanism for these conditions is insulin resistance. In this paper, mechanisms and methods of measurement of insulin resistance are briefly reviewed, and recent studies on the evaluation of insulin resistance in short children with IUGR are summarized. In our experience, short prepubertal children with IUGR show consistent insulin resistance, which becomes particularly evident during pubertal development.

Maternal regulation of fetal development and health in adult life

Babies who are small or disproportionate at birth, or who have altered placental growth are now known to have increased rates of coronary heart disease, hypertension and non-insulin-dependent diabetes in adult life. These associations are thought to result from fetal 'programming', whereby a stimulus or insult at a critical, sensitive period of early life has permanent effects on the body's structure, physiology and metabolism. Small size at birth and disproportion in head size, length and weight appear to be surrogate markers for the actual influences that programme the fetus. These observations have prompted a re-evaluation of the maternal regulation of human fetal development. Recent studies suggest that the fetus may be considerably more sensitive to the materno-placental supply of nutrients than hitherto imagined. Adult cardiovascular disease may be a consequence of fetal adaptations invoked when the materno-placental nutrient supply fails to match the fetal nutrient demand. Understanding the maternal regulation of human fetal development could lead to public health measures that improve the adult health of future generations.

Metabolic consequences of intrauterine growth retardation

Epidemiological studies have revealed strong and reproducible links between indices of poor fetal, and possibly infant, growth and susceptibility to the development of glucose intolerance and insulin resistance syndrome in adult life. The 'thrifty phenotype' hypothesis has been proposed to explain these associations. Key features of the hypothesis are: (i) intrauterine growth retardation has a nutritional basis and the resulting altered fetal environment permanently alters the development and metabolic functions of organs: (ii) these alterations are beneficial to survival in a poor nutritional environment, but may lead to diseases such as non-insulin-dependent diabetes mellitus if nutrition is abundant and obesity occurs in adult life. Tests of this hypothesis in an animal model in which pregnant and/or lactating rats were fed a diet with a reduced protein content have shown that liver metabolism in the offspring is permanently altered despite their being weaned onto a normal diet. The longevity of male offspring may be significantly increased or decreased depending on whether growth retardation is restricted to the period of suckling or pregnancy, respectively. The latter finding raises questions about potentially detrimental effects of 'catch-up' growth.

Relation of cord plasma concentrations of proinsulin, 32-33 split proinsulin, insulin and C-peptide to placental weight and the baby's size and proportions at birth

Small and disproportionate size at birth are associated with type 2 diabetes and coronary heart disease in adult life. Insulin has an important role in controlling growth in utero and we hypothesised that reduced fetal insulin secretion could be one factor underlying these associations. We therefore measured cord plasma concentrations of proinsulin, 32-33 split proinsulin, insulin and C-peptide in 391 babies born at term and related them to the weight of the placenta and to the babies' size and proportions at birth. Babies with a small placental weight and a lower birth weight had lower cord plasma concentrations of split proinsulin and insulin. Babies who were disproportionate, either having a high ratio of head to abdominal circumference or being thin, had lower concentrations of split proinsulin, split proinsulin and insulin. The relations with split proinsulin were especially strong, the geometric mean concentration (pmol/l) falling from 14.2 in babies with a head to abdominal circumference ratio of 101.6% or less to 7.2 in those with a ratio above 107.3% (P < 0.0001), and from 17.4 in babies with a ponderal index above 28.5 kg/m3 to 7.4 in those with a ponderal index of 25.5 kg/m3 or less (P < 0.0001). These findings support the hypothesis that reduced fetal insulin secretion may be one factor underlying the associations between reduced growth in utero and type 2 diabetes and coronary heart disease in adult life.