Perinatal factors associated with subsequent diabetes mellitus in the child: record linkage study

Is socio-economic status associated with risk of childhood type 1 diabetes? Literature review

AIMS

Studies of social inequality and risk of developing type 1 diabetes are inconsistent. The present review aimed to comprehensively review relevant literature and describe what has been reported on socio-economic status or parental occupation and risk of type 1 diabetes in children.

METHODS

We searched for publications between 1 January 1970 and 30 November 2021. We focused on the most recent and/or informative publication in cases of multiple publications from the same data source and referred to these as primary studies.

RESULTS

Our search identified 69 publications with relevant data. We identified eight primary cohort studies with individual-level data, which we considered the highest quality of evidence. Furthermore, we identified 13 primary case-control studies and 14 semi-ecological studies with area-level socio-economic status variables which provided a weaker quality of evidence. Four of eight primary cohort studies contained data on maternal education, showing non-linear associations with type 1 diabetes that were not consistent across studies. There was no consistent pattern on the association of parental occupation and childhood-onset type 1 diabetes.

CONCLUSIONS

There is a need for more high-quality studies, but the existing literature does not suggest a major and consistent role of socio-economic status in the risk of type 1 diabetes.

Maternal smoking during pregnancy and type 1 diabetes in the offspring: a nationwide register-based study with family-based designs

BACKGROUND

Maternal smoking during pregnancy was reported to be associated with a reduced risk of type 1 diabetes in the offspring. We investigated whether this association is consistent with a causal interpretation by accounting for familial (shared genetic and environmental) factors using family-based, quasi-experimental designs.

METHODS

We included 2,995,321 children born in Sweden between 1983 and 2014 and followed them for a diagnosis of type 1 diabetes until 2020 through the National Patient, Diabetes and Prescribed Drug Registers. Apart from conducting a traditional cohort study, we performed a nested case-control study (quasi-experiment) comparing children with type 1 diabetes to their age-matched siblings (or cousins). Information on maternal smoking during pregnancy was retrieved from the Swedish Medical Birth Register. Multivariable adjusted Cox proportional hazards regression and conditional logistic regression were used.

RESULTS

A total of 18,617 children developed type 1 diabetes, with a median age at diagnosis of 9.4 years. The sibling and cousin comparison design included 14,284 and 7988 of these children, respectively. Maternal smoking during pregnancy was associated with a 22% lower risk of offspring type 1 diabetes in the full cohort (hazard ratio 0.78, 95% confidence interval [CI] 0.75-0.82). The corresponding odds ratio was 0.78 (95% CI 0.69-0.88) in the sibling and 0.72 (95% CI 0.66-0.79) in the cousin comparison analysis.

CONCLUSIONS

This nationwide, family-based study provides support for a protective effect of maternal smoking on offspring type 1 diabetes. Mechanistic studies are needed to elucidate the underlying pathways behind this link.

Elevated Anthropometric and Metabolic Indicators among Young Adult Offspring of Mothers with Pregestational Diabetes: Early Results from the Transgenerational Effect on Adult Morbidity Study (the TEAM Study)

Exposure to maternal diabetes in utero increases the risk in the offspring for a range of metabolic disturbances. However, the timing and variability of in utero hyperglycemic exposure necessary to cause impairment have not been elucidated. The TEAM Study was initiated to evaluate young adult offspring of mothers with pregestational diabetes mellitus. This paper outlines the unique enrollment challenges of the TEAM Study and preliminary analysis of the association between exposure to diabetes in pregnancy and adverse metabolic outcomes. The TEAM Study enrolls offspring of women who participated in a Diabetes in Pregnancy (DiP) Program Project Grant between 1978 and 1995. The DiP Study collected medical and obstetric data across pregnancy. The first 96 eligible offspring of women with pregestational diabetes were age-, sex-, and race-matched to adults from the National Health and Nutrition Examination Survey (NHANES) 2015-2016 with an OGTT. Descriptive and regression analyses were employed to compare TEAM participants to NHANES participants. Among a subset of TEAM participants, we compared the metabolic outcomes across maternal glucose profiles using a longitudinal data clustering technique that characterizes level and variability, in maternal glucose across pregnancy. By comparing categories of BMI, TEAM Study participants had over 2.0 times the odds of being obese compared to matched NHANES participants (for class III obesity, OR = 2.81; 95% confidence interval (CI): 1.15, 6.87). Increasing levels of two-hour glucose were also associated with in utero exposure to pregestational diabetes in matched analyses. Exposure to pregestational diabetes in utero may be associated with an increased risk of metabolic impairment in the offspring with clinical implications.

Intestinal Microbiota in Common Chronic Inflammatory Disorders Affecting Children

The incidence and prevalence rate of chronic inflammatory disorders is on the rise in the pediatric population. Recent research indicates the crucial role of interactions between the altered intestinal microbiome and the immune system in the pathogenesis of several chronic inflammatory disorders in children, such as inflammatory bowel disease (IBD) and autoimmune diseases, such as type 1 diabetes mellitus (T1DM) and celiac disease (CeD). Here, we review recent knowledge concerning the pathogenic mechanisms underlying these disorders, and summarize the facts suggesting that the initiation and progression of IBD, T1DM, and CeD can be partially attributed to disturbances in the patterns of composition and abundance of the gut microbiota. The standard available therapies for chronic inflammatory disorders in children largely aim to treat symptoms. Although constant efforts are being made to maximize the quality of life for children in the long-term, sustained improvements are still difficult to achieve. Additional challenges are the changing physiology associated with growth and development of children, a population that is particularly susceptible to medication-related adverse effects. In this review, we explore new promising therapeutic approaches aimed at modulation of either gut microbiota or the activity of the immune system to induce a long-lasting remission of chronic inflammatory disorders. Recent preclinical studies and clinical trials have evaluated new approaches, for instance the adoptive transfer of immune cells, with genetically engineered regulatory T cells expressing antigen-specific chimeric antigen receptors. These approaches have revolutionized cancer treatments and have the potential for the protection of high-risk children from developing autoimmune diseases and effective management of inflammatory disorders. The review also focuses on the findings of studies that indicate that the responses to a variety of immunotherapies can be enhanced by strategic manipulation of gut microbiota, thus emphasizing on the importance of proper interaction between the gut microbiota and immune system for sustained health benefits and improvement of the quality of life of pediatric patients.

Type 1 diabetes in children born after assisted reproductive technology: a register-based national cohort study

STUDY QUESTION

Do children born after assisted reproductive technology (ART) have an increased risk of developing type 1 diabetes?

SUMMARY ANSWER

Children born after ART were found to have an increased risk of type 1 diabetes in the unadjusted analysis, while after adjustment this association was only significant in children born after frozen embryo transfer.

WHAT IS KNOWN ALREADY?

Some studies raise concerns as to whether fertility treatments may influence long-term morbidity in children born after ART. Elevated blood pressure and altered glucose metabolism have been found after ART in a few studies.

STUDY DESIGN, SIZE, DURATION

A register-based national cohort study that included all children born in Sweden between 1985 and 2015-in total, 3 138 540 children-was carried out.

PARTICIPANTS/MATERIAL, SETTING, METHODS

The study was population-based and all live-born singleton children born after ART (n = 47 938) or spontaneous conception (SC) (n = 3 090 602) were included. The ART cohort comprised 36 727 children born after fresh embryo transfer and 11 211 children born after frozen embryo transfer. Several national registries were used together with data from Statistics Sweden.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 202 children born after ART and 17 916 children born after SC developed type 1 diabetes, corresponding to 43.4 and 35.5 per 100 000 person-years at risk (hazard ratio [HR] 1.23; 95% confidence interval [CI], 1.07 to 1.42). Mean follow-up was 9.7 (SD 6.4) years for ART children and 16.3 (SD 9.2) years for SC children. After adjustment for calendar year of birth, HR for type 1 diabetes was 1.13; 95% CI, 0.98-1.30. After further adjustment for sex, maternal age, country of birth, educational level, smoking and parental diabetes, HR was 1.07; 95% CI, 0.93-1.23. In subgroup analyses, an association was found between frozen embryo transfer and type 1 diabetes (adjusted HR 1.52; 95% CI, 1.08-2.14 and 1.41; 95% CI, 1.05-1.89 for frozen versus fresh and frozen versus SC, respectively). When comparing intracytoplasmic sperm injection to in vitro fertilization, no difference was found (adjusted HR 1.08; 95% CI, 0.77-1.51).

LIMITATIONS, REASONS FOR CAUTION

Limitations were the missing data and residual confounding caused by unknown confounders. Furthermore, the control group consisted of all children not conceived by ART and not non-ART children from subfertile mothers. The study was also performed in only singletons and not in the total ART population.

WIDER IMPLICATIONS OF THE FINDINGS

Type 1 diabetes is a serious disease, affecting human life in several ways, including risk of serious complications, reduced life span and a life-long treatment. Our results are generally reassuring, showing no increase in diabetes in ART children compared to children born after SC after adjustment for relevant confounders. The observation of an association between children born after frozen embryo transfer and type 1 diabetes, although based on subgroup analyses with a limited number of children and modest in size, is however a reason for concern.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by Nordforsk 71450, the Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement 70940, and the Hjalmar Svensson Foundation. The authors have no competing interests.

TRIAL REGISTRATION NUMBER

ISRCTN 11780826.

The Association Between High Birth Weight and Long-Term Outcomes-Implications for Assisted Reproductive Technologies: A Systematic Review and Meta-Analysis

Background: Studies have shown that the prevalence of children born with high birth weight or large for gestational age (LGA) is increasing. This is true for spontaneous pregnancies; however, children born after frozen embryo transfer (FET) as part of assisted reproductive technology (ART) also have an elevated risk. In recent years, the practice of FET has increased rapidly and while the perinatal and obstetric risks are well-studied, less is known about the long-term health consequences. Objective: The aim of this systematic review was to describe the association between high birth weight and LGA on long-term child outcomes. Data Sources: PubMed, Scopus, and Web of Science were searched up to January 2021. Exposure included high birth weight and LGA. Long-term outcome variables included malignancies, psychiatric disorders, cardiovascular disease, and diabetes. Study Selection: Original studies published in English or Scandinavian languages were included. Studies with a control group were included while studies published as abstracts and case reports were excluded. Data Extraction: The methodological quality, in terms of risk of bias, was assessed by pairs of reviewers. Robins-I (www.methods.cochrane.org) was used for risk of bias assessment in original articles. For systematic reviews, AMSTAR (www.amstar.ca) was used. For certainty of evidence, we used the GRADE system. The systematic review followed PRISMA guidelines. When possible, meta-analyses were performed. Results: The search included 11,767 articles out of which 173 met the inclusion criteria and were included in the qualitative analysis, while 63 were included in quantitative synthesis (meta-analyses). High birth weight and/or LGA was associated with low to moderately elevated risks for certain malignancies in childhood, breast cancer, several psychiatric disorders, hypertension in childhood, and type 1 and 2 diabetes. Conclusions: Although the increased risks for adverse outcome in offspring associated with high birth weight and LGA represent serious health effects in childhood and in adulthood, the size of these effects seems moderate. The identified risk association should, however, be taken into account in decisions concerning fresh and frozen ART cycles and is of general importance in view of the increasing prevalence in high birthweight babies.

Type 1 diabetes can present before the age of 6 months and is characterised by autoimmunity and rapid loss of beta cells

AIMS/HYPOTHESIS

Diabetes diagnosed at <6 months of age is usually monogenic. However, 10-15% of affected infants do not have a pathogenic variant in one of the 26 known neonatal diabetes genes. We characterised infants diagnosed at <6 months of age without a pathogenic variant to assess whether polygenic type 1 diabetes could arise at early ages.

METHODS

We studied 166 infants diagnosed with type 1 diabetes at <6 months of age in whom pathogenic variants in all 26 known genes had been excluded and compared them with infants with monogenic neonatal diabetes (n = 164) or children with type 1 diabetes diagnosed at 6-24 months of age (n = 152). We assessed the type 1 diabetes genetic risk score (T1D-GRS), islet autoantibodies, C-peptide and clinical features.

RESULTS

We found an excess of infants with high T1D-GRS: 38% (63/166) had a T1D-GRS >95th centile of healthy individuals, whereas 5% (8/166) would be expected if all were monogenic (p < 0.0001). Individuals with a high T1D-GRS had a similar rate of autoantibody positivity to that seen in individuals with type 1 diabetes diagnosed at 6-24 months of age (41% vs 58%, p = 0.2), and had markedly reduced C-peptide levels (median <3 pmol/l within 1 year of diagnosis), reflecting rapid loss of insulin secretion. These individuals also had reduced birthweights (median z score -0.89), which were lowest in those diagnosed with type 1 diabetes at <3 months of age (median z score -1.98).

CONCLUSIONS/INTERPRETATION

We provide strong evidence that type 1 diabetes can present before the age of 6 months based on individuals with this extremely early-onset diabetes subtype having the classic features of childhood type 1 diabetes: high genetic risk, autoimmunity and rapid beta cell loss. The early-onset association with reduced birthweight raises the possibility that for some individuals there was reduced insulin secretion in utero. Comprehensive genetic testing for all neonatal diabetes genes remains essential for all individuals diagnosed with diabetes at <6 months of age. Graphical abstract.

Effect of maternal smoking during pregnancy on childhood type 1 diabetes: a whole-of-population study

AIMS/HYPOTHESIS

Evidence of an association between maternal smoking during pregnancy (prenatal smoking) and childhood type 1 diabetes is mixed. Previous studies have been small and potentially biased due to unmeasured confounding. The objectives of this study were to estimate the association between prenatal smoking and childhood type 1 diabetes, assess residual confounding with a negative control design and an E-value analysis, and summarise published effect estimates from a meta-analysis.

METHODS

This whole-of-population study (births from 1999 to 2013, participants aged ≤15 years) used de-identified linked administrative data from the South Australian Early Childhood Data Project. Type 1 diabetes was diagnosed in 557 children (ICD, tenth edition, Australian Modification [ICD-10-AM] codes: E10, E101-E109) during hospitalisation (2001-2014). Families not given financial assistance for school fees was a negative control outcome. Adjusted Cox proportional HRs were calculated. Analyses were conducted on complete-case (n = 264,542, type 1 diabetes = 442) and imputed (n = 286,058, type 1 diabetes = 557) data. A random-effects meta-analysis was used to summarise the effects of prenatal smoking on type 1 diabetes.

RESULTS

Compared with non-smokers, children exposed to maternal smoking only in the first or second half of pregnancy had a 6% higher type 1 diabetes incidence (adjusted HR 1.06 [95% CI 0.73, 1.55]). Type 1 diabetes incidence was 24% lower (adjusted HR 0.76 [95% CI 0.58, 0.99]) among children exposed to consistent prenatal smoking, and 16% lower for exposure to any maternal smoking in pregnancy (adjusted HR 0.84 [95% CI 0.67, 1.08]), compared with the unexposed group. Meta-analytic estimates showed 28-29% lower risk of type 1 diabetes among children exposed to prenatal smoking compared with those not exposed. The negative control outcome analysis indicated residual confounding in the prenatal smoking and type 1 diabetes association. E-value analysis indicated that unmeasured confounding associated with prenatal smoking and childhood type 1 diabetes, with a HR of 1.67, could negate the observed effect.

CONCLUSIONS/INTERPRETATION

Our best estimate from the study is that maternal smoking in pregnancy was associated with 16% lower childhood type 1 diabetes incidence, and some of this effect was due to residual confounding.

Gestation and lactation exposure to nicotine induces transient postnatal changes in lung alveolar development

Harmful consequences of cigarette smoke (CS) exposure during lung development can already manifest in infancy. In particular, early life exposure to nicotine, the main component of CS, was shown to affect lung development in animal models. We aimed to characterize the effect of nicotine on alveoli formation. We analyzed the kinetics of normal alveolar development during the alveolarization phase and then looked at the effect of nicotine in a mouse model of gestational and early life exposure. Immunohistochemical staining revealed that the wave of cell proliferation [i.e., vascular endothelial cells, alveolar epithelial cells (AEC) type II and mesenchymal cell] occurs at postnatal day (pnd) 8 in control and nicotine-exposed lungs. However, FACS analysis of individual epithelial alveolar cells revealed nicotine-induced transient increase of AEC type I proliferation and decrease of vascular endothelial cell proliferation at pnd8. Furthermore, nicotine increased the percentage of endothelial cells at pnd2. Transcriptomic data also showed significant changes in nicotine samples compared with the controls on cell cycle-associated genes at pnd2 but not anymore at pnd16. Accordingly, the expression of survivin, involved in cell cycle regulation, also follows a different kinetics in nicotine lung extracts. These changes resulted in an increased lung size detected by stereology at pnd16 but no longer in adult age, suggesting that nicotine can act on the pace of lung maturation. Taken together, our results indicate that early life nicotine exposure could be harmful to alveolar development independently from other toxicants contained in CS.

The influence of maternal body mass index, maternal diabetes mellitus, and maternal smoking during pregnancy on the risk of childhood-onset type 1 diabetes mellitus in the offspring: Systematic review and meta-analysis of observational studies

There is emerging evidence that events occurring before and shortly after birth may be important in determining the risk of childhood-onset type 1 diabetes mellitus (T1DM). We aimed to summarize and synthesize the associations between maternal body mass index (BMI), maternal diabetes mellitus (DM), and maternal smoking during pregnancy and the risk of childhood-onset T1DM in the offspring by performing a systematic review and meta-analysis of observational studies. A random effects model was used to generate the summary risk estimates. The PubMed and Web of Science databases were searched to identify relevant observational studies. Twenty one observational studies were included in the present meta-analysis. Compared with offspring of mothers with normal weight, offspring of women with overweight or obesity were at an increased risk of developing childhood-onset T1DM (overweight: relative risk [RR] 1.09, 95% confidence interval [CI], 1.03-1.15; obesity: RR 1.25, 95% CI, 1.16-1.34; per 5 kg m^-2 increase in BMI: RR 1.10, 95% CI, 1.06-1.13). No association was found for maternal underweight (RR 0.92, 95% CI, 0.75-1.13). Maternal DM was associated with an increased risk of childhood-onset T1DM (RR 3.26, 95% CI, 2.84-3.74). Regarding the type of maternal DM, the greatest risk of T1DM in the offspring appeared to be conferred by maternal T1DM (RR 4.46, 95% CI, 2.89-6.89), followed by maternal gestational diabetes mellitus (RR 1.66, 95% CI, 1.16-2.36), and lastly by maternal type 2 diabetes mellitus (RR 1.11, 95% CI, 0.69-1.80). Additional analysis of studies comparing maternal versus paternal T1DM within the same population revealed that offspring of fathers with T1DM had a 1.5 times higher risk of developing childhood-onset T1DM than offspring of mothers with T1DM (RR 9.58, 95% CI, 6.33-14.48 vs. RR 6.24, 95% CI, 5.52-7.07). Furthermore, a reduced risk of childhood-onset T1DM was observed in infants born to mothers who smoked during pregnancy compared with infants born to mothers who did not smoke during pregnancy (RR 0.79, 95% CI, 0.71-0.87). In summary, our findings add further evidence that early-life events or environmental factors may play a role in modulating infants' risk of developing T1DM later in life.

Parental Smoking and Risk of Childhood-onset Type 1 Diabetes

BACKGROUND

A few prospective studies suggest an association between maternal smoking during pregnancy and lower risk of type 1 diabetes. However, the role of unmeasured confounding and misclassification remains unclear.

METHODS

We comprehensively evaluated whether maternal smoking in pregnancy predicts lower risk of childhood-onset type 1 diabetes in two Scandinavian pregnancy cohorts (185,076 children; 689 cases) and a Norwegian register-based cohort (434,627 children; 692 cases). We measured cord blood cotinine as an objective marker of nicotine exposure during late pregnancy in 154 cases and 476 controls. We also examined paternal smoking during pregnancy, in addition to environmental tobacco smoke exposure the first 6 months of life, to clarify the role of characteristics of smokers in general.

RESULTS

In the pregnancy cohorts, maternal smoking beyond gestational week 12 was inversely associated with type 1 diabetes, pooled adjusted hazard ratio (aHR) 0.66 (95% CI = 0.51, 0.85). Similarly, in the Norwegian register-based cohort, children of mothers who still smoked at the end of pregnancy had lower risk of type 1 diabetes, aHR 0.65 (95% CI = 0.47, 0.89). Cord blood cotinine ≥30 nmol/L was also associated with reduced risk of type 1 diabetes, adjusted odds ratio 0.42 (95% CI = 0.17, 1.0). We observed no associations of paternal smoking during pregnancy, or environmental tobacco smoke exposure, with childhood-onset type 1 diabetes.

CONCLUSION

Maternal sustained smoking during pregnancy is associated with lower risk of type 1 diabetes in children. This sheds new light on the potential intrauterine environmental origins of the disease.

Prelabor Cesarean Section and Risk of Childhood Type 1 Diabetes: A Nationwide Register-based Cohort Study

BACKGROUND

Unfavorable conditions associated with cesarean section may influence the risk of type 1 diabetes in offspring, but results from studies are conflicting. We aimed to evaluate the association between prelabor cesarean section and risk of childhood type 1 diabetes.

METHODS

A Danish nationwide cohort study followed all singletons born during 1982-2010. Four national registers provided information on mode of delivery, outcome, and confounders. The risk of childhood type 1 diabetes with onset before the age of 15 years was assessed by Cox regression. A total of 1,760,336 singletons contributed 20,436,684 person-years, during which 4,400 were diagnosed with childhood type 1 diabetes.

RESULTS

The hazard ratio (HR) for childhood type 1 diabetes was increased in children delivered by prelabor cesarean section compared with vaginal delivery when adjusted for year of birth, parity, sex, parental age, and education and paternal type 1 diabetes status at childbirth (HR = 1.2; 95% confidence interval [CI] = 1.0, 1.3), but not after additional adjustment for maternal type 1 diabetes status at childbirth (HR = 1.1; 95% CI = 0.95, 1.2). Delivery by intrapartum cesarean section was not associated with childhood type 1 diabetes. Paternal type 1 diabetes was a stronger risk factor for childhood type 1 (HR = 12; 95% CI = 10, 14) than maternal type 1 diabetes (HR = 6.5; 95% CI = 5.2, 8.0).

CONCLUSIONS

Delivery by prelabor cesarean section was not associated with an increased risk of childhood type 1 diabetes in the offspring.

Infant Feeding and Risk of Type 1 Diabetes in Two Large Scandinavian Birth Cohorts

OBJECTIVE

Our aim was to study the relation between the duration of full and any breastfeeding and risk of type 1 diabetes.

RESEARCH DESIGN AND METHODS

We included two population-based cohorts of children followed from birth (1996-2009) to 2014 (Denmark) or 2015 (Norway). We analyzed data from a total of 155,392 children participating in the Norwegian Mother and Child Cohort Study (MoBa) and the Danish National Birth Cohort (DNBC). Parents reported infant dietary practices when their child was 6 and 18 months old. The outcome was clinical type 1 diabetes, ascertained from nationwide childhood diabetes registries. Hazard ratios (HRs) were estimated using Cox regression.

RESULTS

Type 1 diabetes was identified in 504 children during follow-up, and the incidence of type 1 diabetes per 100,000 person-years was 30.5 in the Norwegian cohort and 23.5 in the Danish cohort. Children who were never breastfed had a twofold increased risk of type 1 diabetes compared with those who were breastfed (HR 2.29 [95% CI 1.14-4.61] for no breastfeeding vs. any breastfeeding for ≥12 months). Among those who were breastfed, however, the incidence of type 1 diabetes was independent of duration of both full breastfeeding (HR per month 0.99 [95% CI 0.97-1.01]) and any breastfeeding (0.97 [0.92-1.03]).

CONCLUSIONS

Suggestive evidence supports the contention that breastfeeding reduces the risk of type 1 diabetes. Among those who were breastfed, however, no evidence indicated that prolonging full or any breastfeeding was associated with a reduced risk of type 1 diabetes.

The impact of abnormal glucose tolerance and obesity on fetal growth

OBJECTIVE

Factors linked with insulin resistance were examined for their association with large-for-gestational-age (LGA) infant birth weight and gestational diabetes.

STUDY DESIGN

Data came from a longitudinal cohort study of 2,305 subjects without overt diabetes, analyzed using multinomial logistic and linear regression.

RESULTS

High maternal BMI (OR = 1.53 (1.11, 2.12)), height (1.98 (1.62, 2.42)), antidepressant use (1.71 (1.20, 2.44)), pregnancy weight-gain exceeding 40 pounds (1.79 (1.25, 2.57)), and high blood sugar (2.68, (1.53, 5.27)) were all positively associated with LGA birth. Strikingly, the difference in risk from diagnosed and treated gestational diabetes compared to women with a single abnormal glucose tolerance test (but no diagnosis of gestational diabetes) was significant (OR = 0.65, p = 0.12 versus OR = 2.84, p < 0.01). When weight/length ratio was used instead, different factors were found to be significant. BMI and pregnancy weight-gain were found to influence the development of gestational diabetes, through an additive interaction.

CONCLUSIONS

High prepregnancy BM, height, antidepressant use, pregnancy weight-gain exceeding 40 pounds, and high blood sugar were associated with LGA birth, but not necessarily infant weight/length ratio. An additive interaction between BMI and pregnancy weight-gain influenced gestational diabetes development.

Can exposure to environmental chemicals increase the risk of diabetes type 1 development?

Type 1 diabetes mellitus (T1DM) is an autoimmune disease, where destruction of beta-cells causes insulin deficiency. The incidence of T1DM has increased in the last decades and cannot entirely be explained by genetic predisposition. Several environmental factors are suggested to promote T1DM, like early childhood enteroviral infections and nutritional factors, but the evidence is inconclusive. Prenatal and early life exposure to environmental pollutants like phthalates, bisphenol A, perfluorinated compounds, PCBs, dioxins, toxicants, and air pollutants can have negative effects on the developing immune system, resulting in asthma-like symptoms and increased susceptibility to childhood infections. In this review the associations between environmental chemical exposure and T1DM development is summarized. Although information on environmental chemicals as possible triggers for T1DM is sparse, we conclude that it is plausible that environmental chemicals can contribute to T1DM development via impaired pancreatic beta-cell and immune-cell functions and immunomodulation. Several environmental factors and chemicals could act together to trigger T1DM development in genetically susceptible individuals, possibly via hormonal or epigenetic alterations. Further observational T1DM cohort studies and animal exposure experiments are encouraged.

Maternal smoking during pregnancy and the risk of childhood type 1 diabetes in Western Australia

AIMS/HYPOTHESIS

The aim of this study was to investigate the association between maternal smoking during pregnancy and type 1 diabetes in the offspring, using complete population data sources available in Western Australia.

METHODS

A prospective cohort study was undertaken with cases defined as children born in Western Australia between 1998 and 2008 who were diagnosed with type 1 diabetes at <15 years of age up to 31 December 2010. Eligible cases were identified from the prospective, population-based Western Australian Children's Diabetes Database. Record linkage was performed to identify perinatal records of cases from the Western Australian Midwives' Notification System, which contains data on >99% of all births in Western Australia. Cox regression was used to analyse the data and adjust for recognised risk factors such as birthweight, gestational age, maternal age and socioeconomic status.

RESULTS

The unadjusted HR for babies born to mothers who smoked during pregnancy being diagnosed with childhood type 1 diabetes was 0.70 (95% CI: 0.50, 0.97). After adjustment, the confidence interval widened but the point estimate remained relatively unchanged at 0.76 (95% CI: 0.54, 1.08).

CONCLUSIONS/INTERPRETATION

Analyses of data from this population-based study indicate that maternal smoking during pregnancy may be associated with a reduced risk of childhood type 1 diabetes. Further investigation in larger populations with more detailed smoking data could lead to novel hypotheses regarding mechanisms that influence the immunopathogenesis of type 1 diabetes in early life.

The prenatal environment and type 1 diabetes

There is ample evidence that environmental factors are involved in the aetiology of type 1 diabetes, but the nature and timing of the interactions are poorly understood. The intrauterine environment is known to play a role in the later development of type 2 diabetes, and this review considers a possible role in type 1 diabetes. Autoimmune type 1 diabetes is rare in those diagnosed before 6 months of age, but endogenous autoantibodies predictive of future type 1 diabetes may be detectable by 6-12 months of age, suggesting that environmental factors may operate before this age in some cases. Indirect evidence of a protective effect for the intrauterine environment comes from the observation that mothers with type 1 diabetes are less likely than affected fathers to transmit diabetes to their offspring, although the precise role (if any) is unclear. The risk of childhood-onset type 1 diabetes increases with maternal age at delivery, and with high birthweight, but these associations are weak and heterogeneous, and these factors are unlikely to be directly causally related to type 1 diabetes. No firm conclusion can be drawn from studies of maternal enteroviral infection or from various nutritional exposures. The birth process itself may play a role, as suggested by the slightly increased risk in children born by Caesarean section; lack of contact with maternal bacteria is one suggested mechanism. In sum, there is circumstantial evidence, but no proof of principle, that maternal or intrauterine conditions may modulate genetic risk of type 1 diabetes. The disease process culminating in type 1 diabetes typically begins in early life, but it is not clear whether the trail begins before or after birth.

Birth weight influences the clinical phenotype and the metabolic control of patients with type 1 diabetes (T1D)

BACKGROUND

High birth weight has been related to an increased risk of type 1 diabetes (T1D), while suboptimal birth weight (both high and low) has been related to obesity, insulin resistance and type 2 diabetes. Insulin resistance, as a consequence of poor metabolic control, has been described in T1D patients. The aims of the study were to analyse the distribution of birth size for gestational age in a large group of T1D patients and to investigate the effect of birth weight on clinical phenotype.

METHODS

Six-hundred two Caucasian T1D patients were evaluated. Small for gestational age (SGA) and large for gestational age (LGA) were defined as birth weight at <3rd percentile and >97th percentile for gestational age, respectively. Birth weights between the 3rd and 97th percentiles were defined as appropriate for gestational age. The clinical characteristics of small, appropriate for gestational age and large were compared. Multivariable linear regression models were fitted to evaluate the independent effects of birth weight and other covariates (age at T1D onset, gender and T1D duration) on different clinical outcomes (body mass index, HbA(1c), insulin requirement, high-density lipoprotein cholesterol and triglycerides).

RESULTS

Thirteen subjects (2.16%) were small (SGA), and 39 (6.48%) were large (LGA). Daily insulin requirement (U/kg/day) was significantly higher in SGA, while body mass index and HbA(1c) were increased in LGA. Multivariable linear regression showed a significant negative effect of birth weight on daily insulin requirement (p < 0.001).

CONCLUSIONS

Suboptimal birth weight (both high and low) in T1D patients seems to be associated with clinical characteristics suggestive of insulin resistance.

Fetal development in women with diabetes: imprinting for a life-time?

OBJECTIVE

To test the hypothesis that fetal exposure to a hyperglycemic intrauterine environment in women with type 1 diabetes is associated with asymmetrically distributed excessive fetal growth and imprinting consistent with adverse health issues later in life.

METHODS

We report findings from a feasibility study on 19 young adults, born to mothers with type 1 diabetes. Long-term follow-up of the offspring in young adulthood included: oral glucose tolerance test, body mass index (BMI), dual X-ray absorptiometry, and blood pressure (BP). We report z-BMI and z-BP to account for varying gender and age.

RESULTS

The young adults born to women with diabetes averaged 19.9 years at follow-up; 37% were female, and 21% African American. Maternal glycohemoglobin A(1) concentration in the 2nd trimester was 9.2% for offspring born with asymmetric LGA and 7.5% for those born with symmetric LGA or AGA. There was significant correlation between maternal glucose control during pregnancy and fasting glucose, z-BMI and z-systolic BP in the young adults.

CONCLUSION

The hyperglycemic intrauterine environment is associated with short-term morbidity, manifested as asymmetric LGA (the "fat" baby). In addition, increasing level of maternal hyperglycemia during pregnancy is associated with increased adiposity and elevated fasting glucose in the young adult offspring.

Early introduction of root vegetables in infancy associated with advanced ß-cell autoimmunity in young children with human leukocyte antigen-conferred susceptibility to Type 1 diabetes

AIMS

Early introduction of supplementary foods has been implicated to play a role in the development of ß-cell autoimmunity. We set out to study the effects of breastfeeding and age at introduction of supplementary foods on the development of ß-cell autoimmunity.

METHODS

A prospective birth cohort of 6069 infants with HLA-DQB-conferred susceptibility to Type 1 diabetes was recruited between 1996 and 2004. Antibodies against islet cells, insulin, glutamate dehydroxylase and islet antigen 2 were measured at 3- to 12-month intervals. The families recorded at home the age at introduction of new foods and, for each visit, completed a structured dietary questionnaire. The endpoint was repeated positivity for islet cell antibodies plus at least one other antibody and/or clinical Type 1 diabetes (n = 265).

RESULTS

Early introduction of root vegetables (by the age of 4 months) was related to increased risk of developing positivity for the endpoint [hazard ratio (95% CI) for the earliest third 1.75 (1.11-2.75) and for the middle third 1.79 (1.22-2.62) compared with the last third (> 4 months), likelihood ratio test P = 0.006], independently of the introduction of other foods and of several putative socio-demographic and perinatal confounding factors. Introducing wheat, rye, oats and/or barley cereals (P = 0.013) and egg (P = 0.031) early was related to an increased risk of the endpoint, but only during the first 3 years of life.

CONCLUSIONS

Early introduction of root vegetables during infancy is independently associated with increased risk of ß-cell autoimmunity among Finnish children with increased genetic susceptibility to Type 1 diabetes.

A meta-analysis of the association between pre-eclampsia and childhood-onset Type 1 diabetes mellitus

AIMS

To review and synthesize the evidence for an increased risk of childhood Type 1 diabetes mellitus in children born to mothers diagnosed with pre-eclampsia during pregnancy.

METHODS

A comprehensive search of the published literature was performed in MEDLINE, Web of Science and EMBASE limited to studies published before August 2010. Crude odds ratios and 95% confidence intervals were calculated from the data reported in each study. Meta-analysis techniques were then used to derive a combined odds ratio and investigate heterogeneity. Sensitivity analyses were conducted by study design, ascertainment of pre-eclampsia and study quality.

RESULTS

Data were available from 16 studies including 8315 children with Type 1 diabetes. Overall, there was little evidence of an increase in the risk of Type 1 diabetes in children born to mothers who had pre-eclampsia during pregnancy (OR = 1.10, 95% CI 0.96-1.27; P = 0.17). This association did not vary much between studies (I(2) = 28%, P for heterogeneity =0.14). The association was similar in three cohort studies (OR = 1.05, 95% CI 0.77-1.44; P = 0.75) and in seven studies with a low risk of bias (OR = 1.13, 95% CI 0.91-1.40; P = 0.27), but was more marked in 13 studies which ascertained pre-eclampsia from obstetrical records or birth registry data (OR = 1.18, 95% CI 1.03-1.36; P = 0.02).

CONCLUSIONS

This analysis demonstrates little evidence of any substantial increase in childhood Type 1 diabetes risk after pregnancy complicated by pre-eclampsia.

Maternal and perinatal factors associated with hospitalised infectious mononucleosis in children, adolescents and young adults: record linkage study

BACKGROUND

There is current interest in the role of perinatal factors in the aetiology of diseases that occur later in life. Infectious mononucleosis (IM) can follow late primary infection with Epstein-Barr virus (EBV), and has been shown to increase the risk of multiple sclerosis and Hodgkin's disease. Little is known about maternal or perinatal factors associated with IM or its sequelae.

METHODS

We investigated perinatal risk factors for hospitalised IM using a prospective record-linkage study in a population in the south of England. The dataset used, the Oxford record linkage study (ORLS), includes abstracts of birth registrations, maternities and in-patient hospital records, including day case care, for all subjects in a defined geographical area. From these sources, we identified cases of hospitalised IM up to the age of 30 years in people for whom the ORLS had a maternity record; and we compared perinatal factors in their pregnancy with those in the pregnancy of children who had no hospital record of IM.

RESULTS

Our data showed a significant association between hospitalised IM and lower social class (p = 0.02), a higher risk of hospitalised IM in children of married rather than single mothers (p < 0.001), and, of marginal statistical significance, an association with singleton birth (p = 0.06). The ratio of observed to expected cases of hospitalised IM in each season was 0.95 in winter, 1.02 in spring, 1.02 in summer and 1.00 in autumn. The chi-square test for seasonality, with a value of 0.8, was not significant.Other factors studied, including low birth weight, short gestational age, maternal smoking, late age at motherhood, did not increase the risk of subsequent hospitalised IM.

CONCLUSIONS

Because of the increasing tendency of women to postpone childbearing, it is useful to know that older age at motherhood is not associated with an increased risk of hospitalised IM in their children. We have no explanation for the finding that children of married women had a higher risk of IM than those of single mothers. Though highly significant, it may nonetheless be a chance finding. We found no evidence that such perinatal factors as birth weight and gestational age, or season of birth, were associated with the risk of hospitalised IM.

Perinatal and early life risk factors for inflammatory bowel disease

AIM: To investigate associations between perinatal risk factors and subsequent inflammatory bowel disease (IBD) in children and young adults.

METHODS: Record linked abstracts of birth registrations, maternity, day case and inpatient admissions in a defined population of southern England. Investigation of 20 perinatal factors relating to the maternity or the birth: maternal age, Crohn’s disease (CD) or ulcerative colitis (UC) in the mother, maternal social class, marital status, smoking in pregnancy, ABO blood group and rhesus status, pre-eclampsia, parity, the infant’s presentation at birth, caesarean delivery, forceps delivery, sex, number of babies delivered, gestational age, birthweight, head circumference, breastfeeding and Apgar scores at one and five minutes.

RESULTS: Maternity records were present for 180 children who subsequently developed IBD. Univariate analysis showed increased risks of CD among children of mothers with CD (P = 0.011, based on two cases of CD in both mother and child) and children of mothers who smoked during pregnancy. Multivariate analysis confirmed increased risks of CD among children of mothers who smoked (odds ratio = 2.04, 95% CI = 1.06-3.92) and for older mothers aged 35+ years (4.81, 2.32-9.98). Multivariate analysis showed that there were no significant associations between CD and 17 other perinatal risk factors investigated. It also showed that, for UC, there were no significant associations with the perinatal factors studied.

CONCLUSION: This study shows an association between CD in mother and child; and elevated risks of CD in children of older mothers and of mothers who smoked.

Potential latent effects of prenatal cocaine exposure on growth and the risk of cardiovascular and metabolic disease in childhood

The literature strongly suggests that prenatal exposure to certain medications and substances does not cause major malformations in early childhood. However, these exposures may have far-reaching latent health effects, such as restricted growth, hypertension, and cardiovascular events in adulthood. We reviewed the literature to identify the effects of prenatal cocaine exposure on growth and the risk of cardiovascular and metabolic disease in late adolescence and early adulthood by examining studies that were published in peer-reviewed English-language journals from 1990 through 2009 and indexed in MEDLINE. We found that animal and clinical studies of the influence of prenatal cocaine exposure on child and adolescent growth and the subsequent development of myocardial and cardiometabolic disease risk factors are few and inconclusive. Studies support the hypothesis that vascular and hemodynamic functions are partially programmed in early life and thus substantially influence vascular aging and arterial stiffening in later life. Sub-optimal fetal nutrition and growth may increase blood pressure and the development of cardiovascular and metabolic disease in late life. How prenatal cocaine and other drug exposure effects this relationship is currently unknown. Despite high rates of cocaine and other drug use during pregnancy (up to 18% in some studies), little is known about the health effects of prenatal cocaine exposure in adolescence and early adulthood. The few studies of early growth deficits persisting into adolescence are inconclusive. The literature provides little information on how exposed children grow into adulthood and about their subsequent risk of cardiometabolic and vascular disease.

Maternal and neonatal risk factors for childhood type 1 diabetes: a matched case-control study

Background

An interaction between genetic susceptibility and environmental factors is thought to be involved in the aetiology of type 1 diabetes. The aim of this study was to investigate maternal and neonatal risk factors for type 1 diabetes in children under 15 years old in Grampian, Scotland.

Methods

A matched case-control study was conducted by record linkage. Cases (n = 361) were children born in Aberdeen Maternity Hospital from 1972 to 2002, inclusive, who developed type 1 diabetes, identified from the Scottish Study Group for the Care of Diabetes in the Young Register. Controls (n = 1083) were randomly selected from the Aberdeen Maternity Neonatal Databank, matched by year of birth. Exposure data were obtained from the Aberdeen Maternity Neonatal Databank. Conditional logistic regression was used to evaluate the association between various maternal and neonatal factors and the risk of type 1 diabetes.

Results

There was no evidence of statistically significant associations between type 1 diabetes and maternal age, maternal body mass index, previous abortions, pre-eclampsia, amniocentesis, maternal deprivation, use of syntocinon, mode of delivery, antepartum haemorrhage, baby's sex, gestational age at birth, birth order, birth weight, jaundice, phototherapy, breast feeding, admission to neonatal unit and Apgar score (P > 0.05). A significantly decreased risk of type 1 diabetes was observed in children whose mothers smoked at the booking appointment compared to those whose mothers did not, with an adjusted OR of 0.67, 95% CI (0.46, 0.99).

Conclusions

This case-control study found limited evidence of a reduced risk of the development of type 1 diabetes in children whose mothers smoked, compared to children whose mothers did not. No evidence was found of a significant association between other maternal and neonatal factors and childhood type 1 diabetes.

Birthweight and the risk of childhood-onset type 1 diabetes: a meta-analysis of observational studies using individual patient data

AIMS/HYPOTHESIS

We investigated whether children who are heavier at birth have an increased risk of type 1 diabetes.

METHODS

Relevant studies published before February 2009 were identified from literature searches using MEDLINE, Web of Science and EMBASE. Authors of all studies containing relevant data were contacted and asked to provide individual patient data or conduct pre-specified analyses. Risk estimates of type 1 diabetes by category of birthweight were calculated for each study, before and after adjustment for potential confounders.Meta-analysis techniques were then used to derive combined ORs and investigate heterogeneity between studies.

RESULTS

Data were available for 29 predominantly European studies (five cohort, 24 case-control studies), including 12,807 cases of type 1 diabetes. Overall, studies consistently demonstrated that children with birthweight from 3.5 to 4 kg had an increased risk of diabetes of 6% (OR 1.06 [95% CI 1.01-1.11]; p=0.02) and children with birthweight over 4 kg had an increased risk of 10% (OR 1.10 [95% CI 1.04-1.19]; p=0.003), compared with children weighing 3.0 to 3.5 kg at birth. This corresponded to a linear increase in diabetes risk of 3% per 500 g increase in birthweight (OR 1.03 [95% CI 1.00-1.06]; p=0.03). Adjustments for potential confounders such as gestational age, maternal age, birth order, Caesarean section, breastfeeding and maternal diabetes had little effect on these findings.

CONCLUSIONS/INTERPRETATION

Children who are heavier at birth have a significant and consistent, but relatively small increase in risk of type 1 diabetes.

Maternal age at birth and childhood type 1 diabetes: a pooled analysis of 30 observational studies

OBJECTIVE

The aim if the study was to investigate whether children born to older mothers have an increased risk of type 1 diabetes by performing a pooled analysis of previous studies using individual patient data to adjust for recognized confounders.

RESEARCH DESIGN AND METHODS

Relevant studies published before June 2009 were identified from MEDLINE, Web of Science, and EMBASE. Authors of studies were contacted and asked to provide individual patient data or conduct prespecified analyses. Risk estimates of type 1 diabetes by maternal age were calculated for each study, before and after adjustment for potential confounders. Meta-analysis techniques were used to derive combined odds ratios and to investigate heterogeneity among studies.

RESULTS

Data were available for 5 cohort and 25 case-control studies, including 14,724 cases of type 1 diabetes. Overall, there was, on average, a 5% (95% CI 2-9) increase in childhood type 1 diabetes odds per 5-year increase in maternal age (P = 0.006), but there was heterogeneity among studies (heterogeneity I(2) = 70%). In studies with a low risk of bias, there was a more marked increase in diabetes odds of 10% per 5-year increase in maternal age. Adjustments for potential confounders little altered these estimates.

CONCLUSIONS

There was evidence of a weak but significant linear increase in the risk of childhood type 1 diabetes across the range of maternal ages, but the magnitude of association varied between studies. A very small percentage of the increase in the incidence of childhood type 1 diabetes in recent years could be explained by increases in maternal age.

Perinatal risk factors for early onset of Type 1 diabetes in a 2000-2005 birth cohort

AIMS

To examine perinatal risk factors for the onset of Type 1 diabetes before 6 years of age, in a 2000-2005 Australian birth cohort.

METHODS

Data from longitudinally linked delivery and hospital admission records (until June 2007) were analysed. Diabetes in mothers and children was identified from International Classification of Diseases 10 diagnosis codes in the hospital records.

RESULTS

There were 272 children admitted to hospital with a first diagnosis of diabetes out of 502 040 live births. Incidence for the infants born in 2000 was 16.0 per 100 000 person-years. Maternal Type 1 diabetes was a significant risk factor [crude relative risk (RR) 6.33], but maternal Type 2 diabetes and gestational diabetes were not significantly associated with diabetes in the child. Late preterm birth (34-36 weeks) (RR 1.64) and caesarean section (RR 1.30) increased the risk of a diabetes admission. Size-for-gestational-age was significantly associated with onset of diabetes (small-for-gestational age RR 0.48), but neither birth weight categories nor birth weight as a continuous variable were associated with risk of diabetes. Increasing maternal age was associated with an increased risk of diabetes in the child (RR 1.13 for each additional 5 years of age).

CONCLUSIONS

This study identified risk factors associated with onset of Type 1 diabetes before 6 years of age, in a recent birth cohort. Size-for-gestational-age had a consistent association with risk of early onset of Type 1 diabetes, small size being protective. Size-for-gestational-age measures should be preferred to birth weight thresholds when assessing risk of diabetes.

Perinatal factors reported by mothers: do they agree with medical records?

As perinatal events have been linked with diseases of later onset, epidemiological studies on child development and adult health require information on the perinatal period. When national neonatal registers do not exist, review of medical records may be impractical. However, neonatal information could be obtained by asking mothers to complete a postal questionnaire using data from the Personal Child Health Record (PCHR). We assessed agreement between medical records and mothers' reports for information on delivery and the newborn's condition at birth, based on the PCHR, a short time after delivery. Of 711 women giving birth in 3 French hospitals and invited to participate in the study, 580 (82%) completed a postal questionnaire 6 weeks after delivery, copying the data recorded in the PCHR when available. Information on pregnancy, delivery and the newborn's health at birth was independently extracted from medical records by physicians of the maternity departments. Agreement between medical records and maternal reports for a range of perinatal factors was assessed in 580 newborn-mother dyads using kappa coefficients. Agreement was excellent for first and second stages of delivery, gestational age, birth weight, birth size and head circumference (kappa coefficients 0.80-1.00) and good for hospitalization during pregnancy, but poor for Apgar scores. With this exception, mothers' reports appeared reliable when compared with medical records. As PCHRs exist in most developed countries, this approach could be used in epidemiological studies on child development to increase the reliability of mothers' reports of their newborn's condition at birth.

Caesarean section is associated with an increased risk of childhood-onset type 1 diabetes mellitus: a meta-analysis of observational studies

AIMS/HYPOTHESIS

The aim of this study was to investigate the evidence of an increased risk of childhood-onset type 1 diabetes in children born by Caesarean section by systematically reviewing the published literature and performing a meta-analysis with adjustment for recognised confounders.

METHODS

After MEDLINE, Web of Science and EMBASE searches, crude ORs and 95% CIs for type 1 diabetes in children born by Caesarean section were calculated from the data reported in each study. Authors were contacted to facilitate adjustments for potential confounders, either by supplying raw data or calculating adjusted estimates. Meta-analysis techniques were then used to derive combined ORs and to investigate heterogeneity between studies.

RESULTS

Twenty studies were identified. Overall, there was a significant increase in the risk of type 1 diabetes in children born by Caesarean section (OR 1.23, 95% CI 1.15-1.32, p < 0.001). There was little evidence of heterogeneity between studies (p = 0.54). Seventeen authors provided raw data or adjusted estimates to facilitate adjustments for potential confounders. In these studies, there was evidence of an increase in diabetes risk with greater birthweight, shorter gestation and greater maternal age. The increased risk of type 1 diabetes after Caesarean section was little altered after adjustment for gestational age, birth weight, maternal age, birth order, breast-feeding and maternal diabetes (adjusted OR 1.19, 95% CI 1.04-1.36, p = 0.01).

CONCLUSIONS/INTERPRETATION

This analysis demonstrates a 20% increase in the risk of childhood-onset type 1 diabetes after Caesarean section delivery that cannot be explained by known confounders.