Accumulating evidence suggest that the concept of programming can also be applied to reproductive development and function, representing an ever expanding research area. Recently issues such as peri- or even preconceptional nutrition, transgenerational effects and underlying mechanisms have received considerable attention. The present chapter presents the existed evidence and reviews the available data from numerous animal and human studies on the effects of early life nutritional environment on adult reproductive function. Specific outcomes depend on the severity, duration and stage of development when nutritional perturbations are imposed, while sex-specific effects are also manifested. Apart from undernutrition, effects of relative overnutrition as well as the complex interactions between pre- and postnatal nutrition is of high importance, especially in the context of our days obesity epidemic. Mechanisms underlying reproductive programming are yet unclear, but may include a role for epigenetic modifications. Epigenetic modulation of critical genes involved in the control of reproductive function and potential intergenerational effects represent an exciting area of interdisciplinary research toward the development of new nutritional approaches during pre- and postnatal periods to ensure reproductive health in later life.

Medically assisted reproductive technologies, such as in vitro embryo production, are increasingly being used to palliate infertility. Eggs are produced following a hormonal regimen that stimulates the ovaries to produce a large number of oocytes. Collected oocytes are then fertilized in vitro and allowed to develop in vitro until they are either frozen or transferred to mothers. There are controversial reports on the adverse impacts of these technologies on early embryos and their potential long-term effects. Using newly developed technological platforms that enable global gene expression and global DNA methylation profiling, we evaluated gene perturbations caused by such artificial procedures. We know that cells in the early embryo produce all cells in the body and are able to respond to their in vitro environment. However, it is not known whether gene perturbations are part of a normal response to the environment or are due to distress and will have long-term impacts. While the mouse is an established genetic model used for quality control of culture media in clinics, the bovine is a large mono-ovulating mammal with similar embryonic kinetics as humans during the studied developmental window. These model systems are critical to understand the effects of assisted reproduction without the confounding impact of infertility and without the limitations imposed by the scarcity of donated human samples and ethical issues. The data presented in this review come mostly from our own experimentation, publications, and collaborations. Together they demonstrate that the in vitro environment has a significant impact on embryos at the transcriptomic level and at the DNA methylation level.

Evidence from previous studies suggests an association between prenatal exposure to famine and increased risk for depression. The aim of this study was to investigate whether prenatal exposure to the Dutch famine is associated with self-reported depression/anxiety and whether a potential association is mediated by the presence of cardio-metabolic disease. A total of 819 persons, born as term singletons around the 1944–1945 Dutch famine, filled out the Hospital Anxiety and Depression Scale (HADS) and were asked about their medical history. As indicators of cardio-metabolic disease we included type 2 diabetes (T2D), hypertension and coronary heart disease (CHD). In the total study population, exposure to famine during early gestation was associated with the presence of self-reported mild-to-severe anxiety. Evidence was found for several interactions between exposure in early gestation and sex. Subsequent analyses according to sex showed that men exposed to famine during early gestation scored higher on the HADS depression scale. Self-reported mild-to-severe anxiety symptoms were more prevalent among early exposed men. No such differences were found in women. T2D and hypertension were not correlated with any of the depression and anxiety measures. Adjusting for the presence of CHD did minimally attenuate the size of the reported associations. In conclusion, the present results do not match those previously reported in prenatally famine-exposed individuals. We found only weak evidence for an association between prenatal famine exposure and symptoms of depression and anxiety, which was shown exclusively in men exposed during early gestation.

Donated oocytes are a treatment modality for female infertility which is also associated with increased risks of preeclampsia. Subsequently it is important to evaluate if there is concomitant increased risks for adverse neonatal events in donated oocyte neonates. A structured search of the literature using PubMed, EMBASE and Cochrane Reviews was performed to investigate the perinatal health outcomes of offspring conceived from donor oocytes compared with autologous oocytes. Meta-analysis was performed on comparable outcomes data. Twenty-eight studies were eligible and included in the review, and of these, 23 were included in a meta-analysis. Donor oocyte neonates are at increased risk of being born with low birth weight (<2500 g) [risk ratio (RR): 1.18, 95% confidence interval (CI): 1.14–1.22, P-value (P)<0.00001], very low birth weight (<1500 g) (RR: 1.24, CI: 1.15–1.35, P<0.00001), preterm (<37 weeks) (RR: 1.26, CI: 1.23–1.30, P<0.00001), of lower gestational age (mean difference −0.3 weeks, CI: −0.35 weeks to −0.25 weeks, P<0.00001), and preterm with low birth weight (RR: 1.24, CI: 1.19–1.29, P<0.00001), when compared with autologous oocyte neonates. Conversely, low birth weight outcomes were improved in term donor oocyte neonates (RR: 0.86, CI: 0.8–0.93, P=0.0003). These negative outcomes remained significant when controlling for multiple deliveries. The donor oocyte risk rates are higher than those found in general ART outcomes, are important considerations for the counselling of infertile patients and may also influence the long term health of the offspring.

Oxidative stress has been linked to many obesity-related conditions among children including cardiovascular disease, diabetes mellitus and hypertension. Exposure to environmental chemicals such as phthalates, ubiquitously found in humans, may also generate reactive oxygen species and subsequent oxidative stress. We examined longitudinal changes of 8-isoprostane urinary concentrations, a validated biomarker of oxidative stress, and associations with maternal prenatal urinary concentrations of phthalate metabolites for 258 children at 5, 9 and 14 years of age participating in a birth cohort residing in an agricultural area in California. Phthalates are endocrine disruptors, and in utero exposure has been also linked to altered lipid metabolism, as well as adverse birth and neurodevelopmental outcomes. We found that median creatinine-corrected 8-isoprostane concentrations remained constant across all age groups and did not differ by sex. Total cholesterol, systolic and diastolic blood pressure were positively associated with 8-isoprostane in 14-year-old children. No associations were observed between 8-isoprostane and body mass index (BMI), BMI Z-score or waist circumference at any age. Concentrations of three metabolites of high molecular weight phthalates measured at 13 weeks of gestation (monobenzyl, monocarboxyoctyl and monocarboxynonyl phthalates) were negatively associated with 8-isoprostane concentrations among 9-year olds. However, at 14 years of age, isoprostane concentrations were positively associated with two other metabolites (mono(2-ethylhexyl) and mono(2-ethyl-5-carboxypentyl) phthalates) measured in early pregnancy. Longitudinal data on 8-isoprostane in this pediatric population with a high prevalence of obesity provides new insight on certain potential cardiometabolic risks of prenatal exposure to phthalates.

Approximately 1–4% of children today are conceived using assisted reproductive technologies (ARTs), including in vitro fertilization (IVF). IVF is considered safe and the great majority of these children are healthy, yet there is increasing physiological and molecular evidence from animal models that ART is associated with postnatal metabolic and cardiovascular alterations. Understanding the mechanisms underlying these changes and determining whether they have biological significance is of paramount importance for optimizing the design of culture conditions and improving the health of ART children across the life course. In this review, we examine the evidence of molecular changes present in adult tissues of rodent offspring generated by preimplantation manipulation of gametes and embryos. Although embryo manipulation in vitro can induce common transcriptional effects in the blastocyst, transcriptional and metabolomic signatures in adult IVF tissues are largely tissue-specific. However, there is pervasive evidence of oxidative stress and metabolic dysfunction, indicating a lasting effect of IVF on molecular physiology.

The association between vitamin D and wheezing in early childhood is unclear. The primary objective of this study was to evaluate the association between vitamin D exposure, during both pregnancy and childhood, and early childhood wheezing. Secondary objectives were to evaluate the associations between vitamin D exposures and asthma and wheezing severity. We conducted a cohort study of children (0–5 years) recruited from 2008 to 2013 through the TARGet Kids! primary-care research network. Vitamin D exposures included maternal vitamin D supplement use during pregnancy, child vitamin D supplementation and children’s 25-hydroxyvitamin D (25(OH)D) concentrations. The outcomes measured were parent-reported childhood wheezing, diagnosed asthma and wheezing severity. Vitamin D supplement and wheezing data were available for 2478 children, and blood samples were available for 1275 children. Adjusted odds ratios (aOR) were estimated using logistic regression adjusted for age, sex, ethnicity, body mass index, birth weight, outdoor play, breastfeeding duration, daycare status, parental smoking and family history of asthma. Vitamin D supplementation during pregnancy was associated with lower odds of childhood wheezing (aOR=0.65; 95% CI: 0.46–0.93). In early childhood, neither 25(OH)D (aOR per 10 nmol/l=1.01; 95% CI: 0.96–1.06) nor vitamin D supplementation (aOR=1.00; 95% CI: 0.81–1.23) was associated with wheezing. No significant associations were observed with diagnosed asthma or wheezing severity. Vitamin D supplementation during pregnancy was associated with reduced odds of wheezing, but child vitamin D supplementation and childhood 25(OH)D were not associated with reduced wheezing. The timing of exposure may be important in understanding the association between vitamin D and childhood wheezing.

The Developmental Origins of Health and Disease (DOHaD) hypothesis refers to the concept that ‘malnutrition during the fetal period induces a nature of thrift in fetuses, such that they have a higher change of developing non-communicable diseases, such as obesity and diabetes, if they grow up in the current well-fed society.’ Epigenetics is a chemical change in DNA and histones that affects how genes are expressed without alterations of DNA sequences. Several lines of evidence suggest that malnutrition during the fetal period alters the epigenetic expression status of metabolic genes in the fetus and that this altered expression can persist, and possibly lead to metabolic disorders. Similarly, mental stress during the neonatal period can alter the epigenetic expression status of neuronal genes in neonates. Moreover, such environmental, stress-induced, epigenetic changes are transmitted to the next generation via an acquired epigenetic status in sperm. The advantage of epigenetic modifications over changes in genetic sequences is their potential reversibility; thus, epigenetic alterations are potentially reversed with gene expression. Therefore, we potentially establish ‘preemptive medicine,’ that, in combination with early detection of abnormal epigenetic status and early administration of epigenetic-restoring drugs may prevent the development of disorders associated with the DOHaD.

Maternal stress has been linked to low birth weight in newborns. One potential pathway involves epigenetic changes at candidate genes that may mediate the effects of prenatal maternal stress on birth weight. This relationship has been documented in stress-related genes, such as NR3C1. There is less literature exploring the effect of stress on growth-related genes. IGF1 and IGF2 have been implicated in fetal growth and development, though via different mechanisms as IGF2 is under imprinting control. In this study, we tested for associations between prenatal stress, methylation of IGF1 and IGF2, and birth weight. A total of 24 mother–newborn dyads in the Democratic Republic of Congo were enrolled. Ethnographic interviews were conducted with mothers at delivery to gather culturally relevant war-related and chronic stressors. DNA methylation data were generated from maternal venous, cord blood and placental tissue samples. Multivariate regressions were used to test for associations between stress measures, DNA methylation and birth weight in each of the three tissue types. We found an association between IGF2 methylation in maternal blood and birth weight. Previous literature on the relationship between IGF2 methylation and birth weight has focused on methylation at known differentially methylated regions in cord blood or placental samples. Our findings indicate there may be links between the maternal epigenome and low birth weight that rely on mechanisms outside known imprinting pathways. It thus may be important to consider the effect of maternal exposures and epigenetic profiles on birth weight even in the setting of maternally imprinted genes such as IGF2.

Analysis of DNA methylation data in epigenome-wide association studies provides many bioinformatics and statistical challenges. Not least of these, are the non-independence of individual DNA methylation marks from each other, from genotype and from technical sources of variation. In this review we discuss DNA methylation data from the Infinium450K array and processing methodologies to reduce technical variation. We describe recent approaches to harness the concordance of neighbouring DNA methylation values to improve power in association studies. We also describe how the non-independence of genotype and DNA methylation has been used to infer causality (in the case of Mendelian randomization approaches); suggest the mediating effect of DNA methylation in linking intergenic single nucleotide polymorphisms, identified in genome-wide association studies, to phenotype; and to uncover the widespread influence of gene and environment interactions on methylation levels.

There are now significant data to support the hypothesis that early life nutrition in the fetus, infant and young child can have profound effects on long-term health. This review considers some of this evidence with specific reference to the current burden of disease in Australia and New Zealand. As the findings of further research become available, recommendations on optimizing early life nutrition should be formulated and made widely available as part of the preventative health policy agenda in both Australia and New Zealand.

Tobacco smoke has both carcinogenic effects and anti-estrogenic properties and its inconsistent association with breast cancer risk in observational studies may be because of these competing effects across the lifecourse. We conducted a prospective study of prenatal smoke exposure, childhood household smoke exposure, and adult active smoke exposure and mammographic density, a strong intermediate marker of breast cancer risk, in an adult follow-up of existing US birth cohorts. Specifically, we followed up women who were born between 1959 and 1967 and whose mothers participated in either the Collaborative Perinatal Project (Boston and Providence sites) or the Childhood Health and Development Study in California. Of the 1134 women interviewed in adulthood (ranging in age from 39 to 49 years at interview), 79% had a screening mammogram. Cigarette smoking was reported by mothers at the time of their pregnancy; 40% of mothers smoked while pregnant. Women whose mothers smoked during pregnancy had a 3.1% (95% confidence interval (CI) = −6.0%, −0.2%) lower mammographic density than women whose mothers did not smoke during pregnancy. When we further accounted for adult body mass index and adult smoking status, the association remained (β = −2.7, 95% CI = −5.0, −0.3). When we examined patterns of smoking, prenatal smoke exposure without adult smoke exposure was associated with a 5.6% decrease in mammographic density (β = −5.6, 95% CI = −9.6, −1.6). Given the strength of mammographic density as an intermediate marker for breast cancer, the inverse associations between mammographic density and smoking patterns across the lifecourse may help explain the complex association between cigarette smoking and breast cancer risk.

Shifts in the maternal gut microbiota have been implicated in the development of gestational diabetes mellitus (GDM). Understanding the interaction between gut microbiota and host glucose metabolism will provide a new target of prediction and treatment. In this nested case-control study, we aimed to investigate the causal effects of gut microbiota from GDM patients on the glucose metabolism of germ-free (GF) mice. Stool and peripheral blood samples, as well as clinical information, were collected from 45 GDM patients and 45 healthy controls (matched by age and prepregnancy body mass index (BMI)) in the first and second trimester. Gut microbiota profiles were explored by next-generation sequencing of the 16S rRNA gene, and inflammatory factors in peripheral blood were analyzed by enzyme-linked immunosorbent assay. Fecal samples from GDM and non-GDM donors were transferred to GF mice. The gut microbiota of women with GDM showed reduced richness, specifically decreased Bacteroides and Akkermansia, as well as increased Faecalibacterium. The relative abundance of Akkermansia was negatively associated with blood glucose levels, and the relative abundance of Faecalibacterium was positively related to inflammatory factor concentrations. The transfer of fecal microbiota from GDM and non-GDM donors to GF mice resulted in different gut microbiota colonization patterns, and hyperglycemia was induced in mice that received GDM donor microbiota. These results suggested that the shifting pattern of gut microbiota in GDM patients contributed to disease pathogenesis.

The use of assisted reproductive technologies (ART) for the treatment of infertility has grown exponentially over the last 20 years, and now accounts for 4% of all births in Australia, and over 1 m births annually around the globe. There is consistent reporting of increased risk of adverse perinatal outcomes and birth defects following infertility treatment. However, change in practice has been stymied by critical knowledge gaps with regards to (a) the relative contribution of patient and treatment factors to adverse outcomes, (b) the independent contribution of specific contemporary treatments and treatment combinations to outcomes, (c) the impact of innovations in laboratory and clinical practice on treatment success and observed risk and (d) changes over time in patient characteristics. Here we summarize key findings from the South Australian Birth Cohort, which is a whole-of-population cohort of over 300,000 births from 1986 to 2002. Relative to spontaneous conceptions, singletons from assisted conception were more likely to be stillborn [odds ratio (OR)=1.82; 95% confidence interval (CI) 1.34–2.48], while survivors as a group were comprehensively disadvantaged at birth, including lower birth weight (OR=2109 g; 95% CI 2129–289), very low birth weight (OR=2.74; 95% CI 2.19–3.43), very preterm birth (OR=2.30; 95% CI 1.82–2.90) and neonatal death (OR=2.04; 95% CI 1.27–3.26). Major birth defects, including cardiac, urogenital and musculoskeletal defects are doubled after fresh ICSI cycles, which is a particular concern as ICSI now accounts for 70% of all treatment cycles globally. Future study is needed to provide contemporary, precise evidence to inform patient and clinic decision making, and generate knowledge for future innovation in ART laboratory methods and clinical practice, thereby optimizing treatment and health outcomes while reducing adverse events.

In epidemiologic analytical studies, the primary goal is to obtain a valid and precise estimate of the effect of the exposure of interest on a given outcome in the population under study. A crucial source of violation of the internal validity of a study involves bias arising from confounding, which is always a challenge in observational research, including life course epidemiology. The increasingly popular approach of meta-analyzing individual participant data from several observational studies also brings up to discussion the problem of confounding when combining data from different populations. In this study, we review and discuss the most common sources of confounding in life course epidemiology: (i) confounding by indication, (ii) impact of baseline selection on confounding, (iii) time-varying confounding and (iv) mediator–outcome confounding. We also discuss the issue of addressing confounding in the context of an individual participant data meta-analysis.

Sarcopenia is defined as the loss of skeletal muscle mass and strength with age. There is increasing recognition of the serious health consequences in terms of disability, morbidity and mortality as well as major healthcare costs. Adult determinants of sarcopenia including age, gender, size, levels of physical activity and heritability have been well described. Nevertheless, there remains considerable unexplained variation in muscle mass and strength between older adults that may reflect not only the current rate of loss but the peak attained earlier in life. To date most epidemiological studies of sarcopenia have focused on factors modifying decline in later life; however, a life course approach to understanding sarcopenia, additionally, focuses on factors operating earlier in life including developmental influences. The epidemiological evidence linking low birth weight with lower muscle mass and strength is strong and consistent with replication in a number of different groups including children, young and older adults. However, most of the evidence for the cellular, hormonal, metabolic and molecular mechanisms underlying these associations comes from animal models. The next stage is to translate the understanding of mechanisms from animal muscle to human muscle enabling progress to be made not only in earlier identification of individuals at risk of sarcopenia but also in the development of beneficial interventions across the life course.

In vitro fertilization (IVF) and its subset intracytoplasmic sperm injection (ICSI), are widely used medical treatments for conception. There has been controversy over whether IVF is associated with adverse short- and long-term health outcomes of offspring. As with other prenatal factors, epigenetic change is thought to be a molecular mediator of any in utero programming effects. Most studies focused on DNA methylation at gene-specific and genomic level, with only a few on associations between DNA methylation and IVF. Using buccal epithelium from 208 twin pairs from the Peri/Postnatal Epigenetic Twin Study (PETS), we investigated associations between IVF and DNA methylation on a global level, using the proxies of Alu and LINE-1 interspersed repeats in addition to two locus-specific regulatory regions within IGF2/H19, controlling for 13 potentially confounding factors. Using multiple correction testing, we found strong evidence that IVF-conceived twins have lower DNA methylation in Alu, and weak evidence of lower methylation in one of the two IGF2/H19 regulatory regions and LINE-1, compared with naturally conceived twins. Weak evidence of a relationship between ICSI and DNA methylation within IGF2/H19 regulatory region was found, suggesting that one or more of the processes associated with IVF/ICSI may contribute to these methylation differences. Lower within- and between-pair DNA methylation variation was also found in IVF-conceived twins for LINE-1, Alu and one IGF2/H19 regulatory region. Although larger sample sizes are needed, our results provide additional insight to the possible influence of IVF and ICSI on DNA methylation. To our knowledge, this is the largest study to date investigating the association of IVF and DNA methylation.

The rise in the occurrence of obesity to epidemic proportions has made it a global concern. Great difficulty has been experienced in efforts to control this growing problem with lifestyle interventions. Thus, attention has been directed to understanding the events of one of the most critical periods of development, perinatal life. Early life adversity driven by maternal obesity has been associated with an increased risk of metabolic disease and obesity in the offspring later in life. Although a mechanistic link explaining the relationship between maternal and offspring obesity is still under investigation, the gut microbiota has come forth as a new factor that may play a role modulating metabolic function of both the mother and the offspring. Emerging evidence suggests that the gut microbiota plays a much larger role in mediating the risk of developing non-communicable disease, including obesity and metabolic dysfunction in adulthood. With the observation that the early life colonization of the neonatal and postnatal gut is mediated by the perinatal environment, the number of studies investigating early life gut microbial establishment continues to grow. This paper will review early life gut colonization in experimental animal models, concentrating on the role of the early life environment in offspring gut colonization and the ability of the gut microbiota to dictate risk of disease later in life.

Lower birthweight, and rapid childhood weight gain predict elevated cardiovascular risk factors in children. We examined associations between serial, detailed, anthropometric measurements from birth to 9.5 years of age and cardiovascular risk markers in Indian children. Children (n = 663) born at the Holdsworth Memorial Hospital, Mysore, India were measured at birth and 6–12 monthly thereafter. At 9.5 years, 539 (255 boys) underwent a 2-h oral glucose tolerance test, and blood pressure (BP) and fasting lipid concentrations were measured. Insulin resistance was calculated using the HOMA equation. These outcomes were examined in relation to birth measurements and changes in measurements (growth) during infancy (0–2 years), 2–5 years and 5–9.5 years using conditional s.d. scores. Larger current weight, height and skinfold thickness were associated with higher risk markers at 9.5 years (P < 0.05). Lower weight, smaller length and mid-arm circumference at birth were associated with higher fasting glucose concentrations at 9.5 years (P ⩽ 0.01). After adjusting for current weight/height, there were inverse associations between birthweight and/or length and insulin concentrations, HOMA, systolic and diastolic BP and plasma triglycerides (P < 0.05). Increases in conditional weight and height between 0–2, 2–5 and 5–9.5 years were associated with higher insulin concentrations, HOMA and systolic BP. In conclusion, in 9–10-year-old Indian children, as in other studies, cardiovascular risk factors were highest in children who were light or short at birth but heavy or tall at 9 years. Greater infant and childhood weight and height gain were associated with higher risk markers.

Recent studies have shown that a low birth weight is a risk factor for increased systemic blood pressure (BP) in adulthood. Further, systemic BP and arterial stiffness (AS) are reported to be increased in adolescents born prematurely. The purpose of this study was to characterize systemic BP and AS in young adults born preterm. Systemic BP was measured using an automated oscillometric device. AS was assessed by measuring the right carotid–radial pulse wave velocity (PWV) using a validated non-invasive automated method. Systemic BP, pulse pressure, and PWV [mean (confidence intervals)] were compared between 16 adults (age 21 years) born preterm (age at birth 32 weeks of gestation) with a birth weight (1710 g) appropriate for their gestational age and 15 adults (21 years) born at term (40 weeks of gestation) with a birth weight (3430 g) appropriate for their gestational age. Adults born preterm had a significantly higher systolic BP [122 mmHg (114–144) v. 112 (106–127)], mean BP [89 mmHg (86–98) v. 84 (81–91)], diastolic BP [69 mmHg (66–76) v. 65 (62–78)], pulse pressure [54 mmHg (47–72) v. 47 (42–60)], and PWV [7 m/s (6.3–8.6) v. 6.4 (5.8–8)] than did those born at term. Our findings suggest that young adults with a low birth weight due to preterm birth have increased systemic BP and AS. Accordingly, preterm birth may predispose individuals to cardiovascular diseases in adulthood due to increased AS.