Seasonal variation of nutrient intake in pregnancy: effects on infant measures and possible influence on diseases related to season of birth

Birth season associates with multiple anthropometric traits in Estonian children

Seasonal variation in maternal exposure to sunlight during pregnancy, which relates to variation in vitamin D and other micronutrient availability for a fetus, is a prevalent explanation for the variation of offspring traits with birth season. However, little consensus exists about the pregnancy period during which the fetus is most sensitive to maternal UV exposure and which offspring traits are most sensitive. We examined the association between 11 anthropometric traits and birth season/month among 18,459-23,876 Estonian children born in 1937-62. Nine traits showed seasonal patterns, which were generally weak, compared to the effects of family socioeconomic position (SEP). Most prominent nonlinear associations between offspring traits and birth month emerged among children of mothers in unskilled manual professions. A possible explanation is that the growth of children in high-SEP families is more strongly buffered against any external exposures (including possible shortage of maternally synthesised vitamin D and essential micronutrient availability) than in low-SEP settings. For most traits, children born in spring/summer were larger than those born in autumn/winter. Hip width, trunk length and weight showed the most distinct seasonal patterns. If these birth-season-related patterns are related to maternal sunlight exposure, our results support the view that UV exposure benefits offspring growth towards the end of pregnancy. It is also possible that children born in spring and summer benefitted from the seasonally increasing nutrient availability during the first post-natal months.

Capacity Planning (Capital, Staff and Costs) of Inpatient Maternity Services: Pitfalls for the Unwary

This study investigates the process of planning for future inpatient resources (beds, staff and costs) for maternity (pregnancy and childbirth) services. The process of planning is approached from a patient-centered philosophy; hence, how do we discharge a suitably rested healthy mother who is fully capable of caring for the newborn baby back into the community? This demonstrates some of the difficulties in predicting future births and investigates trends in the average length of stay. While it is relatively easy to document longer-term (past) trends in births and the conditions relating to pregnancy and birth, it is exceedingly difficult to predict the future nature of such trends. The issue of optimum average bed occupancy is addressed via the Erlang B equation which links number of beds, average bed occupancy and turn-away. Turn-away is the proportion of times that there is not an immediately available bed for the next arriving inpatient. Data for maternity units show extreme and unexplained variation in turn-away. Economy of scale implied by queuing theory (and the implied role of population density) explains why many well intended community-based schemes fail to gain traction. The paper also addresses some of the erroneous ideas around the dogma that reducing length of stay 'saves' money. Maternity departments are encouraged to understand how their costs are calculated to avoid the trap where it is suggested by others that in reducing the length of stay, they will reduce costs and increase 'efficiency'. Indeed, up to 60% of calculated maternity 'costs' are apportioned from (shared) hospital overheads from supporting departments such as finance, personnel, buildings and grounds, IT, information, etc., along with depreciation charges on the hospital-wide buildings and equipment. These costs, known as 'the fixed costs dilemma', are totally beyond the control of the maternity department and will vary by hospital depending on how these costs are apportioned to the maternity unit. Premature discharge, one of the unfortunate outcomes of turn-away, is demonstrated to shift maternity costs into the pediatric and neonatal departments as 'boomerang babies', and then require the cost of avoidable inpatient care. Examples are given from the English NHS of how misdirected government policy can create unforeseen problems.

New perinatal mental health conditions diagnosed during COVID-19: a population-based, retrospective cohort study of birthing people in Ontario

PURPOSE

We aimed to determine the incidence of mental health diagnoses and associated health and social risk factors among perinatal people in three different COVID-19 phases.

METHODS

We conducted a population-based, retrospective cohort study using linked administrative datasets. We included persons with live, in-hospital births in Ontario, Canada from January 1 to March 31 in 2019, 2021, or 2022 (three phases relative to COVID-19 with different public health policy measures). We excluded people with prior mental health diagnoses. We used diagnostic codes to identify new onset of depression, anxiety, or adjustment disorder in the antenatal and postpartum period. We developed multivariable, modified Poisson models to examine associations between sociodemographic and clinical factors and new mental health diagnoses in each phase.

RESULTS

There were 72,242 people in our cohort. Antenatal mental health diagnoses were significantly higher in 2021 (aRR = 1.32; CI = 1.20-1.46) and 2022 (aRR = 1.22; CI = 1.11-1.35) versus 2019. Postpartum diagnoses were significantly greater in 2021 (aRR = 1.16; CI = 1.08-1.25) versus 2019. Antenatal diagnoses were associated with birth year, previous stillbirth, pre-existing hypertension, multiparity, residential instability, and ethnocultural diversity. Postpartum diagnoses were associated with birth year, maternal age, multiparity, care provider profession, assisted reproductive technology, birthing mode, pre-existing hypertension, intensive care admission, hospital readmission, residential instability, and ethnocultural diversity. Family physicians increasingly made mental health diagnoses in 2021 and 2022.

CONCLUSION

Increased incidence of perinatal mental health diagnoses during COVID-19 suggests complex dynamics involving pandemic and health and social risk factors.

REGISTRATION

This study was registered with Clinicaltrials.gov (NCT05663762) on December 21, 2022.

Baby bump? Birth month, family income, and early childhood development

Federal and state laws in the U.S. provide families with babies born just before the end of the year with thousands of dollars in tax savings. Because this income windfall is realized during the first few months of a newborn's life, we assess whether babies born in December experience developmental advantages in early childhood compared to those born right after the New Year. Using data from the Child Development Supplement of the Panel Study of Income Dynamics and the Children of the National Longitudinal Survey of Youth, we implement a regression discontinuity design that exploits variation in birth timing. We first illustrate that the tax savings received by families with end of year babies are substantial. We then show that while children born in December have a weight disadvantage at birth compared to those born in January, they have an average weight-gain advantage of between 0.7 and 1.5 pounds (0.08-0.17 standard deviations) during subsequent follow-up interviews. We also find that end-of-year babies reach early developmental milestones faster, but exhibit no advantage in memory, word recognition, or applied problem solving. This end-of-year birth developmental advantage is consistent with the identified tax savings from end-of-year births.

An epidemiological study of season of birth, mental health, and neuroimaging in the UK Biobank

Environmental exposures during the perinatal period are known to have a long-term effect on adult physical and mental health. One such influential environmental exposure is the time of year of birth which affects the amount of daylight, nutrients, and viral load that an individual is exposed to within this key developmental period. Here, we investigate associations between season of birth (seasonality), four mental health traits (n = 137,588) and multi-modal neuroimaging measures (n = 33,212) within the UK Biobank. Summer births were associated with probable recurrent Major Depressive Disorder (β = 0.026, pcorr = 0.028) and greater mean cortical thickness in temporal and occipital lobes (β = 0.013 to 0.014, pcorr<0.05). Winter births were associated with greater white matter integrity globally, in the association fibers, thalamic radiations, and six individual tracts (β = -0.013 to -0.022, pcorr<0.05). Results of sensitivity analyses adjusting for birth weight were similar, with an additional association between winter birth and white matter microstructure in the forceps minor and between summer births, greater cingulate thickness and amygdala volume. Further analyses revealed associations between probable depressive phenotypes and a range of neuroimaging measures but a paucity of interactions with seasonality. Our results suggest that seasonality of birth may affect later-life brain structure and play a role in lifetime recurrent Major Depressive Disorder. Due to the small effect sizes observed, and the lack of associations with other mental health traits, further research is required to validate birth season effects in the context of different latitudes, and by co-examining genetic and epigenetic measures to reveal informative biological pathways.

Seasonal patterns in newborns' health: Quantifying the roles of climate, communicable disease, economic and social factors

Poor health at birth can have long-term consequences for children's development. This paper analyses an important factor associated with health at birth: the time of year that the baby is born, and hence seasonal risks they were exposed to in utero. There are multiple potential explanations for seasonality in newborns' health. Most previous research has examined these in isolation. We therefore do not know which explanations are most important - and hence which policy interventions would most effectively reduce the resulting early-life inequalities. In this paper, I use administrative data to estimate and compare the magnitudes of several seasonal risks, seeking to identify the most important drivers of seasonality in the Northern Territory of Australia, a large territory spanning tropical and arid climates and where newborn health varies dramatically with the seasons. I find that the most important explanations are heat exposure and disease prevalence. Seasonality in food prices and road accessibility have smaller effects on some outcomes. Seasonal fertility patterns, rainfall and humidity do not have statistically significant effects. I conclude that interventions that protect pregnant women from seasonal disease and heat exposure would likely improve newborn health in the Northern Territory, with potential long-term benefits for child development. It is likely that similar impacts would apply in other locations with tropical and arid climates, and that, without action, climate change will accentuate these risks.

How do perceptions of Covid-19 risk impact pregnancy-related health decisions? A convergent parallel mixed-methods study protocol

INTRODUCTION

Pregnant people have a higher risk of severe COVID-19 disease. They have been disproportionately impacted by COVID-19 infection control policies, which exacerbated conditions resulting in intimate partner violence, healthcare access, and mental health distress. This project examines the impact of accumulated individual health decisions and describes how perinatal care and health outcomes changed during the COVID-19 pandemic.

OBJECTIVES

Quantitative strand: Describe differences between 2019, 2021, and 2022 birth groups related to maternal vaccination, perinatal care, and mental health care. Examine the differential impacts on racialized and low-income pregnant people.Qualitative strand: Understand how pregnant people's perceptions of COVID-19 risk influenced their decision-making about vaccination, perinatal care, social support, and mental health.

METHODS AND ANALYSIS

This is a Canadian convergent parallel mixed-methods study. The quantitative strand uses a retrospective cohort design to assess birth group differences in rates of Tdap and COVID-19 vaccination, gestational diabetes screening, length of post-partum hospital stay, and onset of depression, anxiety, and adjustment disorder, using administrative data from ICES, formerly the Institute for Clinical Evaluative Sciences (Ontario) and PopulationData BC (PopData) (British Columbia). Differences by socioeconomic and ethnocultural status will also be examined. The qualitative strand employs qualitative description to interview people who gave birth between May 2020- December 2021 about their COVID-19 risk perception and health decision-making process. Data integration will occur during design and interpretation.

ETHICS AND DISSEMINATION

This study received ethical approval from McMaster University and the University of British Columbia. Findings will be disseminated via manuscripts, presentations, and patient-facing infographics.

TRIAL REGISTRATION

Registration: Clinicaltrials.gov registration number: NCT05663762.

Patterns of maternal gestational weight gain in association with allergic diseases in offspring: A prospective cohort study

OBJECTIVE

To evaluate the association between patterns of gestational weight gain (GWG) and allergic diseases in offspring.

DESIGN

Prospective cohort study.

SETTING

Prenatal clinics in Wuhan, China.

POPULATION

A cohort of 2546 mother and offspring pairs were enrolled before 16 weeks of gestation and followed up to 24 months postpartum.

METHODS

Maternal body weights were measured regularly during pregnancy, and their GWG patterns were estimated using the growth mixture model. Robust Poisson models were used to evaluate relative risk (RR) and 95% CI after multivariable adjustment.

MAIN OUTCOME MEASURES

Offspring atopic allergy and allergic contact dermatitis were defined according to a physician's diagnosis reported by the mother, and food allergy was reported by the mother.

RESULTS

Three GWG patterns were identified: 18.1% (461) of the women were described as pattern 1, characterised by rapid GWG earlier in pregnancy; 56.6% (1442) of the women were described as pattern 2, with steady GWG throughout pregnancy; and 25.3% (643) of the women was described as pattern 3, with rapid GWG later in pregnancy. By the age of 24 months, 360 (14.1%), 109 (4.3%) and 757 (29.7%) offspring had atopic allergy, allergic contact dermatitis or food allergy, respectively. Compared with women in GWG pattern 2, the RRs (95% CIs) among women in pattern 1 were 0.74 (0.55-0.99) for atopic allergy, 0.64 (0.36-1.15) for allergic contact dermatitis and 0.95 (0.81-1.12) for food allergy.

CONCLUSIONS

Maternal GWG pattern characterised by rapid GWG earlier in pregnancy was associated with a lower risk of atopic allergy in offspring.

Maternal nutritional status and offspring childlessness: Evidence from the late-nineteenth to early-twentieth centuries in a group of Italian populations

The role of maternal nutrition in affecting offspring fertility, through alteration of foetal programming, has been demonstrated in animal-based experiments. However, results from human populations appear inconsistent and sometimes contradictory, likely because they have been based on single famine events. In this paper, we adopt a different approach. We combine official annual time series of daily nutrient availability with a sample of women's reproductive histories from the 1961 Italian Census to investigate the role of maternal nutritional status in pregnancy on offspring childlessness. The analysis therefore covers cohorts of females born between 1861 and 1939. Our results show a negative association between calorie availability in pregnancy and the odds of offspring childlessness, whereas no association is found between protein availability and offspring childlessness. The consequences of poor calorie intake were aggravated during the summer, likely due to the participation of pregnant women in physically demanding work.

Comparative Analysis of Docosahexaenoic Acid (DHA) Content in Mother's Milk of Term and Preterm Mothers

Objectives and Study: Docosahexaenoic acid (DHA) plays an essential role in infants’ development. Maternal diet and breastmilk are the primary DHA sources for newborns. This single-center observational study aimed to compare the DHA content in mother’s milk of preterm mothers with that of term ones, and to investigate the changes in mother’s milk DHA content according to the week of the gestational age. Methods: A food frequency questionnaire (FFQ) was submitted to each mother to estimate the DHA intake during the last trimester of pregnancy, and the mother’s milk was collected between 24 and 96 h post-partum. Results: Women who gave birth prematurely showed a lower content of mother’s milk DHA than the term ones (0.51; IQR 0.38−0.6% FA vs. 0.71; IQR 0.52−0.95% FA; p = 0.001). In the multivariate linear regression analyses, for each additional week of gestational age, there was an increase in DHA content in the mother’s milk (0.046% FA; CI 95% 0.018−0.074; p < 0.001). Conclusions: Our results suggest that breast milk may not be sufficient to fully satisfy the recommended DHA intake in preterm infants. This study may represent a starting point to investigate new possible DHA supplementation strategies, especially for the late and moderate preterm infants.

Dietary carotenoid intake and risk of developing preeclampsia: a hospital-based case-control study

Background

The effect of carotenoids on the risk of preeclampsia (PE) is uncertain. We aimed to examine the associations between the intake of dietary carotenoids and related compounds by pregnant women in China, and the risk of their developing PE.

Methods

Four hundred and forty PE cases and 440 age- (± 3 years), gestational age- (± 1 weeks) and gestational diabetes mellitus status- (yes/no) matched healthy controls were recruited from March 2016 to June 2019. Dietary intake of carotenoids was assessed using a 79-item validated food-frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression.

Results

After adjusting for potential confounders, we found that the intake of total carotenoids, β-carotene, β-cryptoxanthin, lycopene, and lutein and zeaxanthin (lut-zea) were negatively associated with the odds of developing PE. Compared with the lowest quartile intake, the multivariate-adjusted OR (95% CI) of the highest quartile intake was 0.29 (0.16–0.54, P_trend <  0.001) for total carotenoids, 0.31 (0.16–0.58, P_trend <  0.001) for β-carotene, 0.50 (0.27–0.90, P_trend = 0.007) for β-cryptoxanthin, 0.55 (0.30–0.99, P_trend = 0.04) for lycopene and 0.32 (0.17–0.61, P_trend = 0.001) for lut-zea. However, no significant associations were observed between the risk of developing PE and α-carotene intake (OR = 0.75, 95% CI: 0.41–1.36, P_trend = 0.28). Moreover, similar negative associations were found for every one-standard-deviation increase in the intake of total carotenoids, β-carotene, β-cryptoxanthin, lycopene and lut-zea.

Conclusion

These results indicate that a high intake of total carotenoids, β-carotene, β-cryptoxanthin, lycopene and lut-zea may be associated with a low risk of developing PE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04737-5.

Infant Iodine and Selenium Status in Relation to Maternal Status and Diet During Pregnancy and Lactation

Iodine and selenium are essential trace elements. Recent studies indicate that pregnant and lactating women often have insufficient intake of iodine and selenium, but the impact on fetal and infant status is unclear. Here, we assessed iodine and selenium status of infants in relation to maternal intake and status of these trace elements in the birth cohort NICE, conducted in northern Sweden (n = 604). Iodine was measured in urine (UIC) in gestational week 29, and in breast milk and infant urine 4 months postpartum, while selenium was measured in maternal plasma and erythrocytes in gestational week 29, and in breast milk and infant erythrocytes 4 months postpartum, in both cases using ICP-MS. Maternal intake was assessed with semi-quantitative food frequency questionnaires in gestational week 34 and at 4 months postpartum. The median intake of iodine and selenium during pregnancy (98 and 40 μg/d, respectively) and lactation (108 and 39 μg/d, respectively) was below recommended intakes, reflected in insufficient status (median UIC of 113 μg/L, median plasma selenium of 65 μg/L). Also, breast milk concentrations (median iodine 77 μg/L, median selenium 9 μg/L) were unlikely to meet infant requirements. Median UIC of the infants was 114 μg/L and median erythrocyte selenium 96 μg/kg, both similar to the maternal concentrations. Infant UIC correlated strongly with breast milk levels (rho = 0.64, p < 0.001). Their erythrocyte selenium correlated with maternal erythrocyte selenium in pregnancy (rho = 0.38, p < 0.001), but not with breast milk selenium, suggesting formation of prenatal reserves. Our results indicate that the transport of iodine and selenium to the fetus and infant is prioritized. Still, it is uncertain whether most infants had sufficient intakes. Further, the results might indicate an involvement of iodine in asthma development during the first year of life, which is essential to follow up. The low maternal and infant dietary intake of both iodine and selenium, especially when the mothers did not use supplements or iodized table salt, suggest a need for a general screening of women and young children.

Temporal variations in maternal treatment requirements and early neonatal outcomes in patients with gestational diabetes

AIMS

There is seasonal variation in the incidence of gestational diabetes (GDM) and delivery outcomes of affected patients. We assessed whether there was also evidence of temporal variation in maternal treatment requirements and early neonatal outcomes.

METHODS

We performed a retrospective analysis of women diagnosed with GDM (75 g oral glucose tolerance test, 0 h ≥ 5.1; 1 h ≥ 10.0; 2 h ≥ 8.5 mmol/L) in a UK tertiary obstetric centre (2015-2019) with a singleton infant. Data regarding demographic characteristics, total insulin requirements and neonatal outcomes were extracted from contemporaneous electronic medical records. Linear/logistic regression models using month of the year as a predictor of outcomes were used to assess annual variation.

RESULTS

In all, 791 women (50.6% receiving pharmacological treatment) and 790 neonates were included. The likelihood of requiring insulin treatment was highest in November (p < 0.05). The average total daily insulin dose was higher at peak (January) compared to average by 19 units/day (p < 0.05). There was no temporal variation in neonatal intensive care admission, or neonatal capillary blood glucose. However, rates of neonatal hypoglycaemia (defined as <2.6 mmol/L) were highest in December (40% above average; p < 0.05).

CONCLUSIONS

Women with GDM diagnosed in winter are more likely to require insulin treatment and to require higher insulin doses. Neonates born to winter-diagnosed mothers had a corresponding increased risk of neonatal hypoglycaemia. Maternal treatment requirements and neonatal outcomes of GDM vary significantly throughout the year, even in a relatively temperate climate.

The effect of season of birth on brain epigenome-wide DNA methylation of older adults

Perinatal light exposure predisposes towards health and behaviour in adulthood. Season of birth is associated with psychiatric, allergic, cardiovascular and metabolic problems. It has been proposed that early-life environmental light disrupts the development of biological rhythms which, in turn, influence later-life health. However, the mechanisms linking perinatal seasonal light to later-life biological rhythm and health in humans are unknown. In this study, we investigated the association between season of birth and epigenome-wide DNA methylation of two postmortem human brain regions (16 hypothalamus, 14 temporal cortex). We did not find statistically significant differences at the whole epigenome level, either because we lacked statistical power or that no association exists. However, when we examined 24 CpG sites that had the highest significance or differential methylation, we identified regions which may be associated with circadian rhythm entrainment, cholinergic neurotransmission and neural development. Amongst methylation of the core clock genes, we identified that hypothalamus Neuronal PAS Domain Protein 2 (NPAS2) gene has hypermethylated regions in long photoperiod-born individuals. In addition, we found nominal associations between season of birth and genes linked to chronotype and narcolepsy. Season of birth-related brain DNA methylation profile was different than a previously reported blood methylation profile, suggesting a tissue-specific mechanism of perinatal light programming. Overall, we are the first to analyse the relationship between season of birth and human brain DNA methylation. Further studies with larger sample sizes are required to confirm an imprinting effect of perinatal light on the circadian clock.

Prenatal and Perinatal Environmental Influences Shaping the Neonatal Immune System: A Focus on Asthma and Allergy Origins

It is suggested that programming of the immune system starts before birth and is shaped by environmental influences acting during critical windows of susceptibility for human development. Prenatal and perinatal exposure to physiological, biological, physical, or chemical factors can trigger permanent, irreversible changes to the developing immune system, which may be reflected in cord blood of neonates. The aim of this narrative review is to summarize the evidence on the role of the prenatal and perinatal environment, including season of birth, mode of delivery, exposure to common allergens, a farming environment, pet ownership, and exposure to tobacco smoking and pollutants, in shaping the immune cell populations and cytokines at birth in humans. We also discuss how reported disruptions in the immune system at birth might contribute to the development of asthma and related allergic manifestations later in life.

Seasonality, climate change, and food security during pregnancy among Indigenous and non-Indigenous women in rural Uganda: Implications for maternal-infant health

BACKGROUND

Climate change is expected to decrease food security globally. Many Indigenous communities have heightened sensitivity to climate change and food insecurity for multifactorial reasons including close relationships with the local environment and socioeconomic inequities which increase exposures and challenge adaptation to climate change. Pregnant women have additional sensitivity to food insecurity, as antenatal undernutrition is linked with poor maternal-infant health. This study examined pathways through which climate change influenced food security during pregnancy among Indigenous and non-Indigenous women in rural Uganda. Specific objectives were to characterize: 1) sensitivities to climate-associated declines in food security for pregnant Indigenous women; 2) women's perceptions of climate impacts on food security during pregnancy; and 3) changes in food security and maternal-infant health over time, as observed by women.

METHODS

Using a community-based research approach, we conducted eight focus group discussions-four in Indigenous Batwa communities and four in non-Indigenous communities-in Kanungu District, Uganda, on the subject of climate and food security during pregnancy. Thirty-six women with ≥1 pregnancy participated. Data were analysed using a constant comparative method and thematic analysis.

RESULTS

Women indicated that food insecurity was common during pregnancy and had a bidirectional relationship with antenatal health issues. Food security was thought to be decreasing due to weather changes including extended droughts and unpredictable seasons harming agriculture. Women linked food insecurity with declines in maternal-infant health over time, despite improved antenatal healthcare. While all communities described food security struggles, the challenges Indigenous women identified and described were more severe.

CONCLUSIONS

Programs promoting women's adaptive capacity to climate change are required to improve food security for pregnant women and maternal-infant health. These interventions are particularly needed in Indigenous communities, which often face underlying health inequities. However, resiliency among mothers was strong and, with supports, they can reduce food security challenges in a changing climate.

Parathyroid Hormone in Pregnancy: Vitamin D and Other Determinants

We aimed to assess the parathyroid hormone (PTH) concentration in pregnant women at the beginning of pregnancy (1st trimester) and within days before delivery (3rd trimester) and evaluate its determinants. From September 2014 through December 2015 in a cross-sectional study, 204 women in the 1st trimester of pregnancy and 203 women in the 3rd trimester of pregnancy were recruited. Blood samples were collected to measure PTH and circulating 25-hydroxy-vitamin D (25(OH)D) concentrations. Lifestyle and demographic data were collected using a questionnaire. Serum 25(OH)D and PTH were inversely correlated in both early and late pregnancy. Our analyses suggest that in the 3rd trimester of pregnancy, a 25(OH)D level of 18.9 ng/mL (47.3 nmol/L) could serve as an inflection point for the maximal suppression of PTH. Statistically significant determinants of PTH concentrations in multiple regression were 25(OH)D concentrations, season, multiparity and education of the partner (all p < 0.05) in early pregnancy. In late pregnancy, 25(OH)D concentrations and country of origin were statistically significant determinants of PTH concentrations (all p < 0.05). These factors and their effect on PTH appear to be vastly determined by 25(OH)D; however, they might also affect PTH through other mechanisms besides 25(OH)D.

Season-of-birth phenomenon in health and longevity: epidemiologic evidence and mechanistic considerations

In many human populations, especially those living in regions with pronounced climatic differences between seasons, the most sensitive (prenatal and neonatal) developmental stages occur in contrasting conditions depending on the season of conception. The difference in prenatal and postnatal environments may be a factor significantly affecting human development and risk for later life chronic diseases. Factors potentially contributing to this kind of developmental programming include nutrition, outdoor temperature, infectious exposures, duration of sunlight, vitamin D synthesis, etc. Month of birth is commonly used as a proxy for exposures which vary seasonally around the perinatal period. Season-of-birth patterns have been identified for many chronic health outcomes. In this review, the research evidence for the seasonality of birth in adult-life disorders is provided and potential mechanisms underlying the phenomenon of early life seasonal programming of chronic disease and longevity are discussed.

Impact of sunshine on the risk of gestational diabetes mellitus in primiparous women

There is a lack of data about the influence of sunshine hours on the prevalence for gestational diabetes mellitus (GDM). The aim of this study was to evaluate whether the prevalence of GDM varied according to hours of daily sunshine during the first trimester. The study cohort (N = 6189) consists of all primiparous women with a Finnish background who delivered between 2009 and 2015 living in Vantaa city, Finland. Data on births and maternal characteristics were obtained from National Health Registers. Data on sunshine hours were obtained from the Finnish Meteorological Institute. Individual daily sunshine hours during the first trimester of pregnancy were calculated for each woman. Diagnosis of GDM was based on a standard 75-g 2-h glucose tolerance test (OGTT). No relationship was observed between month of conception and GDM. Daily sunshine hours during the first trimester and GDM showed a U-shaped association (adjusted p-value 0.019). In OGTT, a U-shaped association was observed between 0-h glucose value and daily sunshine hours during the first trimester (p = 0.039) as well as with the 1-h glucose value (p = 0.012), respectively. In primiparous women daily sunshine hours during the first trimester showed a U-shaped association with the prevalence of GDM independent of pre-pregnancy risk factors.

Abbreviations: BMI: body mass index; GDM: gestational diabetes mellitus; OGTT: standard 75 g 2-h glucose tolerance test; SD: standard deviation

Season of birth and biomarkers of early-life environment

OBJECTIVE

Early-life conditions play an important role in human development, affecting health status and survival. Conditions in utero partly depend on the external environment and thus vary in relation to the season of birth. The aim of this study was to investigate if people born in different seasons of the year differ in values of biomarkers that reflect conditions during fetal development.

METHODS

The study was conducted among Polish rural women recruited at the Mogielica Human Ecology Study Site. The participants were 234 women aged 45 to 92 (mean = 60.2; SD = 10.44). The indicators of early-life environment analyzed in the study were: Absolute Finger Ridge Count (AFRC), the difference between mean number of ridge counts in both thumbs and both little fingers (Md15), overall facial fluctuating asymmetry (OFA), central facial asymmetry (CFA), right and left hand 2D:4D.

RESULTS

Values of biomarkers of fetal development did not vary among groups of women born in different seasons of the year.

CONCLUSIONS

Lack of differences in values of biomarkers according to birth season may indicate that: (a) season of birth is not a good indicator of early-life conditions; (b) tested biomarkers do not reliably reflect the prenatal environment; (c) season of birth does not fully overlap with the sensitive periods of biomarker development and thus fails to capture differences in developmental conditions.

Maternal total energy, macronutrient and vitamin intakes during pregnancy associated with the offspring's birth size in the Japan Environment and Children's Study

Maternal diet during pregnancy can influence fetal growth; however, the available evidence is controversial. We aimed to assess whether maternal diet of Japanese women in mid-pregnancy can affect their offspring's birth size via collection of questionnaire and medical record data. The studied sample was a large cohort of paired mothers and their singleton offspring (n 78 793) from fifteen areas all over Japan who participated in the Japan Environment and Children's Study. The mid-pregnancy intakes of total energy, macronutrients and vitamins were lower than the recommended intakes for pregnant Japanese women. Maternal total energy intake was positively associated with the offspring's birth weight; there was a 10-g mean difference in the offspring's birth weight of mothers in the lowest (3026 g) v. highest (3036 g) quartiles of energy intake. Carbohydrate intake was positively associated with the offspring's birth length (mean difference of 0·7 cm) and inversely associated with the ponderal index (mean difference of 0·8 g/cm3). Offspring of mothers in the highest v. lowest quartiles of total dietary fibre intake were on average 9 g heavier and had 0·3 cm longer birth length and 0·2 cm longer head circumference. The highest in reference to lowest intake quartile of vitamin C was associated with 13 g and 0·7 cm mean differences in the offspring's birth weight and length, respectively. Several other associations were evident for maternal intakes of vitamins and the offspring's birth size. In conclusion, maternal dietary intakes of energy, dietary fibre, carbohydrate and vitamins during pregnancy were associated with the offspring's birth size.

Associations between birth season and the anatomic subsites of gastric cancer in Beijing, China

Birth season is an important risk factor for several cancers; for example, anatomic subsite risk factors for gastric cancer differ substantially by when patients were born. In this population-based retrospective study, we explored the relationship between birth season and gastric cancer of different anatomical sites, focusing on gastric cancer patients who were registered at the Beijing Institute for Cancer Research from 2003 to 2012. In total, 19,668 patients were divided into three groups according to the anatomical site of the primary lesion: cardia (n = 3911), noncardia (n = 5383) and unknown (n = 10,374). The 5383 patients in the noncardia group were further subdivided into the following subgroups: fundus (n = 455), corpus (n = 902), greater curvature (n = 110), lesser curvature (n = 512), antrum (n = 2635), pylorus (n = 106) and overlapping (n = 663). Finally, all gastric cancer cases, the three major groups, and the seven noncardia subgroups were, respectively, compared with inpatients from the Dongzhimen Hospital of Beijing from 2003 to 2013. A logistic regression method with sex and age as control factors was used to evaluate the relationship between birth season and gastric cancer with the level for statistical significance set at P < .05. Taking winter as the reference season, we found people born in summer had a lower probability of developing gastric cancer (summer: odds ratio [OR] = 0.925, 95% confidence interval [CI] = 0.875-0.978, P = .006). Among the three groups, the noncardia group had the lower probability of birth season being spring or summer (spring: OR = 0.917, 95% CI = 0.843-0.997, P = .042; summer: OR = 0.883, 95% CI = 0.810-0.962, P = .004), but the cardia and unknown anatomical groups showed no statistical significance for season of birth (P > .05). Among the seven subgroups, those born in summer were less likely to develop gastric cancer in the antrum and lesser curvature than those born in winter (antrum: OR = 0.861, 95% CI = 0.766-0.968, P = .012; lesser curvature: OR = 0.746, 95% CI = 0.579-0.961, P = .023); the other subgroups showed no significant differences by season of birth (P > .05). This study demonstrated that gastric cancer is related to birth season. For people born in summer, the risk of developing gastric cancer was comparatively lower than for people born in winter. Seasonal differences in immune function and maternal nutrition status during pregnancy may explain these findings; however, further large-scale prospective studies will be required to validate these findings.

Seasonally variant gene expression in full-term human placenta

Seasonal exposures influence human health and development. The placenta, as a mediator of the maternal and fetal systems and a regulator of development, is an ideal tissue to understand the biological pathways underlying relationships between season of birth and later life health outcomes. Here, we conducted a differential expression (DE) analysis of season of birth in full-term human placental tissue to evaluate whether the placenta may be influenced by seasonal cues. Of the analyzed transcripts, 583 displayed DE between summer and winter births (False Discovery Rate [FDR] q < .05); among these, BHLHE40, MIR210HG, and HILPDA had increased expression among winter births (Bonferroni P < .05). Enrichment analyses of the seasonally variant genes between summer and winter births indicated overrepresentation of transcription factors HIF1A, VDR, and CLOCK, among others, and of GO term pathways related to ribosomal activity and infection. Additionally, a cosinor analysis found rhythmic expression for approximately 11.9% of all 17 664 analyzed placental transcripts. These results suggest that the placenta responds to seasonal cues and add to the growing body of evidence that the placenta acts as a peripheral clock, which may provide a molecular explanation for the extensive associations between season of birth and health outcomes.

Vitamin D in early life and later risk of multiple sclerosis-A systematic review, meta-analysis

The study examined results from previous studies of early life vitamin D exposure and risk of MS in adulthood, including studies on season or month of birth and of migration. A systematic review was conducted using PubMed and Web of Science databases as well as checking references cited in articles. The quality of studies was assessed using the Newcastle-Ottawa scale and the AMSTAR score. Twenty-eight studies were selected for analysis. Of these, six population studies investigated early life vitamin D exposure and risk of MS, and three found inverse while the remaining found no associations. A consistent seasonal tendency for MS seemed evident from 11/15 studies, finding a reduced occurrence of MS for Northern hemisphere children who were born late autumn, and late fall for children born in the Southern hemisphere. This was also confirmed by pooled analysis of 6/15 studies. Results of the migration studies showed an increased risk of MS if migration from high to low-MS-risk areas had occurred after age 15 years, while risk of MS was reduced for those migrating earlier in life (<15years). A similar, but inverse risk pattern was observed among migrants from low to high-MS-risk areas. One study found an increased risk of MS in the second generation of migrants when migrating from low to high-MS-risk areas. An association between early life vitamin D and later risk of MS seems possible, however evidence is still insufficient to conclude that low vitamin D exposure in early life increases the risk of MS in adulthood.

PROSPERO register number: CRD 42016043229.

The Dietary Intake and Its Features across Four Seasons in the Metropolis of China

Chinese diet pattern known as plant-based is more linked with seasonal supply, but it is lack of study on seasonal difference in dietary intakes in China. Our study was to assess seasonal variation in the absolute dietary intake among general population in a metropolis, Shanghai, China. A representative sample of general population aged 15 and older (n=1,704) were randomly stratified-sampled from communities in Shanghai. Dietary survey included consecutive 3-day-24-hour diet record recall and household condiments weighing. Data was collected across four seasons during 2012-2014. Most of food and condiments consumption differed across seasons in Shanghai. Intakes of grains, legumes and cooking oil were highest in spring; vegetables, fruit and non-alcoholic beverage highest, but cooking oil and cooking salt lowest in summer; red meat, nuts and cooking salt highest in winter. Seasonality existed in the intakes of energy and energy contributed from macronutrients that fat contributed more in winter but less in summer. Seasonal variations were also found in beta-carotene, vitamin E, vitamin K, thiamin, folate and sodium intakes. Seasonal changes of dietary intake were extensively observed in Shanghai, a highly-developed metropolis in China. Given the seasonal differences and their features described in current article, the estimation methods of the average dietary intake across whole year by just conducting dietary survey in one single season warrants further study.

Carotenoid Content in Breastmilk in the 3rd and 6th Month of Lactation and Its Associations with Maternal Dietary Intake and Anthropometric Characteristics

Carotenoids are diet-dependent milk components that are important for the visual and cognitive development of an infant. This study determined β-carotene, lycopene and lutein + zeaxanthin in breastmilk and its associations with dietary intake from healthy Polish mothers in the first six months of lactation. Concentrations of carotenoids in breastmilk were measured by HPLC (high-performance liquid chromatography) (first, third, sixth month of lactation) and dietary intake was assessed based on a three-day dietary record (third and sixth month of lactation). The average age of participants (n = 53) was 31.4 ± 3.8 years. The breastmilk concentrations of carotenoids were not changed over the progress of lactation. Lycopene was a carotenoid with the highest content in breastmilk (first month 112.2 (95% CI 106.1⁻118.3)-sixth month 110.1 (103.9⁻116.3) nmol/L) and maternal diet (third month 7897.3 (5465.2⁻10329.5) and sixth month 7255.8 (5037.5⁻9474.1) µg/day). There was a positive correlation between carotenoids in breastmilk and dietary intake (lycopene r = 0.374, r = 0.338; lutein + zeaxanthin r = 0.711, r = 0.726, 3rd and 6th month, respectively) and an inverse correlation with maternal BMI in the third month of lactation (β-carotene: r = -0.248, lycopene: r = -0.286, lutein + zeaxanthin: r = -0.355). Adjusted multivariate regression models confirmed an association between lutein + zeaxanthin intake and its concentration in breastmilk (third month: β = 0.730 (0.516⁻0.943); 6th: β = 0.644 (0.448⁻0.840)). Due to the positive associations between dietary intake and breastmilk concentrations, breastfeeding mothers should have a diet that is abundant in carotenoids.

Environmental grass pollen levels in utero and at birth and cord blood IgE: Analysis of three birth cohorts

BACKGROUND

Early life factors are associated with allergic respiratory diseases, but the role of high grass pollen concentrations during pregnancy and shortly after birth is not known.

OBJECTIVE

To assess outdoor levels of grass pollen during the intrauterine period and at birth during peak pollen season on cord blood IgE in birth cohorts.

METHODS

Three birth cohorts were included: MACS (n = 429), Australia; COPSAC₂₀₀₀ (n = 200), Denmark; and LISA (n = 1968), Germany. Cord blood IgE was categorized (<0.5 kU/L, 0.5-1 kU/L, >1 kU/L) and dichotomized (high IgE ≥ 0.5 kU/L). Birth during the grass pollen season months and cumulative exposure to outdoor grass pollen counts during pregnancy with cord blood IgE were analysed using multinomial regression and analysed in meta-analysis using binomial regression adjusted for potential confounders.

RESULTS

Birth during the grass pollen season had higher pooled odds of cord blood IgE >0.5 kU/L 1.37 (95% CI 1.06, 1.77) in a meta-analysis with little heterogeneity between the three cohorts. Cumulative exposure to outdoor grass pollen counts during the entire pregnancy was associated with slightly lower pooled odds but significant (OR = 0.98, 95% CI: 0.96 to 0.99).

CONCLUSIONS

Birth during grass pollen seasons were associated with increased risk of high cord blood IgE in cities from both hemispheres, but high pollen loads in the environment during the entire pregnancy appeared protective. As IgE responses develop during the first months of life, our study findings provide new insights into the mechanisms of grass pollen exposure at birth and shortly after on possible allergic respiratory diseases.

Seasonality of hypertensive disorders of pregnancy - A South Australian population study

OBJECTIVES

To investigate the seasonal variation of hypertensive disorders of pregnancy (HDP) in South Australia.

STUDY DESIGN

Retrospective population study including all 107,846 liveborn singletons during 2007-2014 in South Australia. Seasonality in incidence of HDP in relation to estimated date of conception (eDoC) and date of birth (DoB) were examined using Fourier series analysis.

MAIN OUTCOME MEASURES

Seasonality of HDP in relation to eDoC and DoB.

RESULTS

During 2007-2014, the incidence of HDP was 7.1% (n = 7,612). Seasonal modeling showed a strong relationship between HDP and eDoC (p < .001) and DoB (p < .001). Unadjusted and adjusted models (adjusted for maternal age, body mass index, ethnicity, parity, type of health care, smoking and gestational diabetes mellitus) demonstrated the presence of a peak incidence (7.8%, 7.9% respectively) occurring among pregnancies with eDoC in late Spring (November) and a trough (6.4% and 6.3% respectively) among pregnancies with eDoC in late Autumn (May). Both unadjusted and adjusted seasonal modelling showed a peak incidence of HDP for pregnancies with DoB in August (8.0%, 8.1% respectively) and a nadir among pregnancies with eDoB in February (6.2%).

CONCLUSION

The highest incidence of HDP was associated with pregnancies with eDoC during late spring and summer and birth in winter, while the lowest incidence of HDP was associated with pregnancies with eDoC during late autumn and early winter and birth in summer. Nutrient intake, in particular vitamin D, sunlight exposure and physical activity may affect maternal, fetal and placental adaptation to pregnancy and are potential contributors to the seasonal variation of HDP.

Low perinatal zinc status is not associated with the risk of type 1 diabetes in children

AIM

Immunologic events during fetal life may play a part in the pathogenesis of type 1 diabetes (T1D). As zinc is involved in immunologic processes, the purpose was to investigate perinatal zinc status and the later risk of developing T1D and association to age at onset.

METHODS

A population-based case-control study based on data from Danish Childhood Diabetes Register and the Danish Newborn Screening Biobank. Cases and controls were matched by birth year and month. Zinc status was analyzed in dried blood spots collected 5 to 7 days after birth. Logistic regression model was used to test the influence of zinc on risk of T1D. Linear regression modeling was used to examine the association between zinc status and covariates as well as age at onset. Zinc status was adjusted for HLA-DQB1 genotype, birth data and maternal age.

RESULTS

Each doubling in perinatal zinc status was not associated with T1D risk; odds ratio (OR) = 1.06 (95% confidence interval [CI] 0.84, 1.32) ( P  = 0.62), adjusted for birth year and season. This finding persisted after adjustment for possible confounders; OR = 1.01 (95% CI 0.77, 1.34) ( P  = 0.93). In none of the cohorts there were significant associations to age at onset.

CONCLUSION

The risk of developing T1D in Danish children was not associated with perinatal zinc status nor age at onset.

Health Effects of Carotenoids during Pregnancy and Lactation

Adequate nutrition is particularly important during pregnancy since it is needed not only for maintaining the health of the mother, but also determines the course of pregnancy and its outcome, fetus development as well as the child’s health after birth and during the later period of life. Data coming from epidemiological and interventions studies support the observation that carotenoids intake provide positive health effects in adults and the elderly population. These health effects are the result of their antioxidant and anti-inflammatory properties. Recent studies have also demonstrated the significant role of carotenoids during pregnancy and infancy. Some studies indicate a correlation between carotenoid status and lower risk of pregnancy pathologies induced by intensified oxidative stress, but results of these investigations are equivocal. Carotenoids have been well studied in relation to their beneficial role in the prevention of preeclampsia. It is currently hypothesized that carotenoids can play an important role in the prevention of preterm birth and intrauterine growth restriction. Carotenoid status in the newborn depends on the nutritional status of the mother, but little is known about the transfer of carotenoids from the mother to the fetus. Carotenoids are among the few nutrients found in breast milk, in which the levels are determined by the mother’s diet. Nutritional status of the newborn directly depends on its diet. Both mix feeding and artificial feeding may cause depletion of carotenoids since infant formulas contain only trace amounts of these compounds. Carotenoids, particularly lutein and zeaxanthin play a significant role in the development of vision and nervous system (among others, they are important for the development of retina as well as energy metabolism and brain electrical activity). Furthermore, more scientific evidence is emerging on the role of carotenoids in the prevention of disorders affecting preterm infants, who are susceptible to oxidative stress, particularly retinopathy of prematurity.

Effect of season of birth on cord blood IgE and IgE at birth: A systematic review and meta-analysis

BACKGROUND

Elevated cord blood IgE is important on the pathway to allergic disease. The association between season of birth and infant cord blood IgE is not well-established. Study findings differ on which birth season is associated with higher cord blood IgE risk and its magnitude. We conducted a systematic review and meta-analysis of studies on season of birth and cord blood IgE.

METHODS

We searched Medline, Web of Science, Scopus and ProQuest Health databases, and reviewed reference lists of articles that met the inclusion criteria. All included studies measured IgE as a binary variable using various cut-off values. We performed multivariate-random-effects meta-analysis to handle an exposure with multiple categories of Season of Birth.

RESULTS

Our search identified 275 records and 10 had sufficient data to be included in a meta-analysis. Relative to summer, winter birth had the greatest odds of high IgE (≥ 0.1IU/ml), meta-analysis OR = 1.24 (95%CI: 1.01-1.52). A similar OR, was found for IgE ≥ 0.5 IU/ml, OR = 1.30 (95%CI: 0.99-1.71).

CONCLUSIONS

A winter season of birth was associated with statistically significant higher odds of elevated cord blood IgE at cut-off ≥ 0.1IU/ml but borderline at cut-off ≥ 0.5IU/ml. This winter effect is likely to be a marker for a range of other environmental exposures during specific stages of pregnancy, such as aeroallergen exposures, maternal infections and vitamin D levels. Further research is required to support our finding and to identify the exact mechanisms that lead to the winter season of birth effect on circulating IgE levels, as this may have implications for allergic disease prevention.

Influence of Diet in Multiple Sclerosis: A Systematic Review

Nutrition is considered to be a possible factor in the pathogenesis of the neurological disease multiple sclerosis (MS). Nutrition intervention studies suggest that diet may be considered as a complementary treatment to control the progression of the disease; a systematic review of the literature on the influence of diet on MS was therefore conducted. The literature search was conducted by using Medlars Online International Literature (MEDLINE) via PubMed and Scopus. Forty-seven articles met the inclusion criteria. The reviewed articles assessed the relations between macro- and micronutrient intakes and MS incidence. The patients involved used alternative therapies (homeopathy), protocolized diets that included particular foods (herbal products such as grape seed extract, ginseng, blueberries, green tea, etc.), or dietary supplements such as vitamin D, carnitine, melatonin, or coenzyme Q10. Current studies suggest that high serum concentrations of vitamin D, a potent immunomodulator, may decrease the risk of MS and the risk of relapse and new lesions, while improving brain lesions and timed tandem walking. Experimental evidence suggests that serum vitamin D concentration is lower during MS relapses than in remission and is associated with a greater degree of disability [Expanded Disability Status Scale (EDSS) score >3]. The findings suggest that circulating vitamin D concentrations can be considered a biomarker of MS and supplemental vitamin D can be used therapeutically. Other studies point to a negative correlation between serum vitamin B-12 concentrations and EDSS score. Vitamin B-12 has fundamental roles in central nervous system function, especially in the methionine synthase-mediated conversion of homocysteine to methionine, which is essential for DNA and RNA synthesis. Therefore, vitamin B-12 deficiency may lead to an increase in the concentration of homocysteine. Further research is clearly necessary to determine whether treatment with vitamin B-12 supplements delays MS progression.

Modeling month-season of birth as a risk factor in mouse models of chronic disease: from multiple sclerosis to autoimmune encephalomyelitis

Month-season of birth (M-SOB) is a risk factor in multiple chronic diseases, including multiple sclerosis (MS), where the lowest and greatest risk of developing MS coincide with the lowest and highest birth rates, respectively. To determine whether M-SOB effects in such chronic diseases as MS can be experimentally modeled, we examined the effect of M-SOB on susceptibility of C57BL/6J mice to experimental autoimmune encephalomyelitis (EAE). As in MS, mice that were born during the M-SOB with the lowest birth rate were less susceptible to EAE than mice born during the M-SOB with the highest birth rate. We also show that the M-SOB effect on EAE susceptibility is associated with differential production of multiple cytokines/chemokines by neuroantigen-specific T cells that are known to play a role in EAE pathogenesis. Taken together, these results support the existence of an M-SOB effect that may reflect seasonally dependent developmental differences in adaptive immune responses to self-antigens independent of external stimuli, including exposure to sunlight and vitamin D. Moreover, our documentation of an M-SOB effect on EAE susceptibility in mice allows for modeling and detailed analysis of mechanisms that underlie the M-SOB effect in not only MS but in numerous other diseases in which M-SOB impacts susceptibility.-Reynolds, J. D., Case, L. K., Krementsov, D. N., Raza, A., Bartiss, R., Teuscher, C. Modeling month-season of birth as a risk factor in mouse models of chronic disease: from multiple sclerosis to autoimmune encephalomyelitis.

Early-Life Nutritional Programming of Type 2 Diabetes: Experimental and Quasi-Experimental Evidence

Consistent evidence from both experimental and human studies suggest that inadequate nutrition in early life can contribute to risk of developing metabolic disorders including type 2 diabetes (T2D) in adult life. In human populations, most findings supporting a causative relationship between early-life malnutrition and subsequent risk of T2D were obtained from quasi-experimental studies (‘natural experiments’). Prenatal and/or early postnatal exposures to famine were demonstrated to be associated with higher risk of T2D in many cohorts around the world. Recent studies have highlighted the importance of epigenetic regulation of gene expression as a possible major contributor to the link between the early-life famine exposure and T2D in adulthood. Findings from these studies suggest that prenatal exposure to the famine may result in induction of persistent epigenetic changes that have adaptive significance in postnatal development but can predispose to metabolic disorders including T2D at the late stages of life. In this review, quasi-experimental data on the developmental programming of T2D are summarized and recent research findings on changes in DNA methylation that mediate these effects are discussed.

Brighter children? The association between seasonality of birth and child IQ in a population-based birth cohort

OBJECTIVE

Season of birth has repeatedly been found to be a risk indicator for adverse neurodevelopmental outcomes. Several explanations for this finding have been put forward but no conclusion has been reached. In the current study, we explored the role of sociodemographic and biological factors in the association between season of birth and child IQ.

DESIGN

In a prenatally recruited birth cohort (born in 2002-2006), we examined the association between season of birth and non-verbal IQ at age 6 years among 6034 children. We explored how adjusting for socioeconomic status and maternal IQ, childbirth outcomes, pregnancy vitamin D status, nutritional intake, exposure to infections, and child age relative to peers in class changed the relation between season of birth and child IQ.

RESULTS

We found that spring birth was associated with lower non-verbal IQ (estimate: more than 1 point; β-1.24 (95% CI -2.31 to -0.17), p=0.02; seasonal trend β-0.40 (95% CI -0.74 to -0.07), p=0.02) than birth in summer. Adjustment for different covariates led to a substantial reduction (-65.0% change, in a seasonal trend analysis) of this association. In particular, sociodemographic factors and maternal IQ (-10.0% and -22.5% change, respectively) contributed.

CONCLUSIONS

Season of birth is an indicator of many underlying factors related to child IQ. The observed effects on IQ were small and therefore not of clinical significance.

The relationship between 25-hydroxyvitamin D concentration in early pregnancy and pregnancy outcomes in a large, prospective cohort

Vitamin D insufficiency and deficiency have been associated with an increased risk of adverse pregnancy outcomes. Controversy remains as findings have been inconsistent between disparate populations. The aim of this study was to investigate the relationship between vitamin D status and pregnancy outcomes in a large, prospective pregnancy cohort. 25-Hydroxyvitamin D concentration was analysed in serum samples collected at 15 weeks of gestation from 1710 New Zealand women participating in a large, observational study. Associations between vitamin D status and pre-eclampsia, preterm birth, small for gestational age (SGA) and gestational diabetes were investigated. The mean 25-hydroxyvitamin D concentration was 72·9 nmol/l. In all, 23 % had 25-hydroxyvitamin D concentrations <50 nmol/l, and 5 % of participants had concentrations <25 nmol/l. Women with 25-hydroxyvitamin D concentrations <75 nmol/l at 15 weeks of gestation were more likely to develop gestational diabetes mellitus than those with concentrations >75 nmol/l (OR 2·3; 95 % CI 1·1, 5·1). However, this effect was not significant when adjustments were made for BMI and ethnicity (OR 1·8; 95 % CI 0·8, 4·2). 25-Hydroxyvitamin D concentration at 15 weeks was not associated with development of pre-eclampsia, spontaneous preterm birth or SGA infants. Pregnancy complications were low in this largely vitamin D-replete population.

Association of season of birth with DNA methylation and allergic disease

BACKGROUND

Season of birth influences allergy risk; however, the biological mechanisms underlying this observation are unclear. The environment affects DNA methylation, with potentially long-lasting effects on gene expression and disease. This study examined whether DNA methylation could underlie the association between season of birth and allergy.

METHODS

In a subset of 18-year-old participants from the Isle of Wight (IoW) birth cohort (n = 367), the risks of birth season on allergic outcomes were estimated. Whole blood epigenome-wide DNA methylation was measured, and season-associated CpGs detected using a training-and-testing-based technique. Validation method examined the 8-year-old Prevention and Incidence of Asthma and Mite Allergy (PIAMA) cohort. The relationships between DNA methylation, season of birth and allergy were examined. CpGs were analysed in IoW third-generation cohort newborns.

RESULTS

Autumn birth increased risk of eczema, relative to spring birth. Methylation at 92 CpGs showed association with season of birth in the epigenome-wide association study. In validation, significantly more CpGs had the same directionality than expected by chance, and four were statistically significant. Season-associated methylation was enriched among networks relating to development, the cell cycle and apoptosis. Twenty CpGs were nominally associated with allergic outcomes. Two CpGs were marginally on the causal pathway to allergy. Season-associated methylation was largely absent in newborns, suggesting it arises post-natally.

CONCLUSIONS

This study demonstrates that DNA methylation in adulthood is associated with season of birth, supporting the hypothesis that DNA methylation could mechanistically underlie the effect of season of birth on allergy, although other mechanisms are also likely to be involved.

Seasonality of gestational diabetes mellitus: a South Australian population study

OBJECTIVE

To investigate whether there is a seasonal variation in the incidence of gestational diabetes mellitus (GDM).

RESEARCH DESIGN AND METHODS

This retrospective cohort study of 60 306 eligible South Australian live-born singletons during 2007-2011 recorded in the South Australian Perinatal Statistics Collection (SAPSC) examined the incidence of GDM in relation to estimated date of conception (eDoC). Fourier series analysis was used to model seasonal trends.

RESULTS

During the study period, 3632 (6.0%) women were diagnosed with GDM. Seasonal modeling showed a strong relation between GDM and eDoC (p<0.001). Unadjusted and adjusted models (adjusted for maternal age, body mass index (BMI), parity, ethnicity, socioeconomic status, and chronic hypertension) demonstrated the presence of a peak incidence occurring among pregnancies with eDoC in winter (June/July/August), with a trough for eDoc in summer (December/January/February). As this was a retrospective study, we could only use variables that had been collected as part of the routine registration system, the SAPSC.

CONCLUSIONS

This study is the first population-based study to demonstrate a seasonal variation for GDM. Several maternal lifestyle and psychosocial factors associated with seasonality and GDM may be influential in the pathophysiologic mechanisms of GDM. Ambient temperature, physical activity, nutrient intake, and vitamin D levels may affect maternal physiology, and fetal and placental development at the cellular level and contribute to the development of GDM. The mechanisms underlying these possible associations are not fully understood and warrant further investigation.

Season of birth shapes neonatal immune function

BACKGROUND

Birth season has been reported to be a risk factor for several immune-mediated diseases. We hypothesized that this association is mediated by differential changes in neonatal immune phenotype and function with birth season.

OBJECTIVE

We sought to investigate the influence of season of birth on cord blood immune cell subsets and inflammatory mediators in neonatal airways.

METHODS

Cord blood was phenotyped for 26 different immune cell subsets, and at 1 month of age, 20 cytokines and chemokines were quantified in airway mucosal lining fluid. Multivariate partial least squares discriminant analyses were applied to determine whether certain immune profiles dominate by birth season, and correlations between individual cord blood immune cells and early airway immune mediators were defined.

RESULTS

We found a birth season-related fluctuation in neonatal immune cell subsets and in early-life airway mucosal immune function. The seasonal airway immune pattern was associated with the number of activated and regulatory T cells in cord blood whereas it was independent of concomitant presence of pathogenic airway microbes. Specifically, summer newborns presented with the lowest levels of all cell types and mediators; fall newborns displayed high levels of activated T cells and mucosal IL-12p70, TNF-α, IL-13, IL-10, and IL-2; and winter newborns had the highest levels of innate immune cells, IL-5, type 17-related immune mediators, and activated T cells.

CONCLUSION

Birth season fluctuations seem to affect neonatal immune development and result in differential potentiation of cord blood immune cells and early airway mucosal immune function.

Dietary Intake Patterns Are Consistent Across Seasons in a Cohort of Healthy Adults in a Metropolitan Population

BACKGROUND

Current literature provides conflicting data regarding seasonal variability in dietary intake.

OBJECTIVE

Our aim was to examine seasonal variation in dietary intake in healthy adults from the metropolitan Washington, DC, area.

DESIGN

This study utilized an observational cohort design.

PARTICIPANTS/SETTING

Male and female healthy volunteers (n=103) between the ages of 18 and 75 years were recruited from the metropolitan Washington, DC, area to participate in a clinical study at the National Institutes of Health Clinical Center from February 2011 to June 2014.

MAIN OUTCOME MEASURES

Three- to seven-day food records were collected from subjects (n=76) at three time points (12 to 15 weeks apart). Subjects were excluded from analysis (n=27) if they completed less than three time points. Food records were reviewed by nutrition staff, assigned to a season, and coded in Nutrient Data System for Research for energy, macronutrient, micronutrient, and food-group serving analysis.

STATISTICAL ANALYSES

Multivariate general linear models were run on energy, macronutrient, micronutrient, and food-group intakes, while being adjusted for age, sex, race, and body mass index (calculated as kg/m(2)).

RESULTS

Subjects had a mean±standard deviation body mass index of 25±3.9 and age of 34±12.4 years. Subject demographics were 71.1% white, 9.2% black/African American, 13.2% Asian, and 6.6% unknown race, with 44.7% males and 55.3% females. Mean intake of energy across seasons was 2,214.6±623.4 kcal with 17.3%±4.1%, 33.6%±5.5%, 46.6%±8.0%, and 2.7%±3.2% of calories from protein, fat, carbohydrate, and alcohol, respectively. Intakes of energy, macronutrients, micronutrients, and food groups did not differ between seasons.

CONCLUSIONS

People living in the metropolitan Washington, DC, area did not exhibit seasonal variation in dietary intake. Therefore, when designing studies of nutrient intake in a metropolitan population, these findings suggest that investigators do not need to consider the season during which diet is examined.

Season of birth and subclinical psychosis: systematic review and meta-analysis of new and existing data

Season of birth (SOB) has been shown to modify the risk of several health outcomes, including a number of neuropsychiatric disorders. Empirical evidence indicates that subclinical forms of psychosis in the general population share some risk factors with categorical diagnoses of psychosis. Hence, by systematically reviewing and meta-analyzing new and existing data, the current work aimed to determine whether there is evidence of an association between winter SOB and subclinical psychosis in the general population. Our meta-analytic results do not indicate an association between winter SOB and schizotypy in adult populations, although they indicate winter SOB may be a risk factor for psychotic experiences or symptoms in children around 12-15 years (OR=1.12, 95%CI:1.03-1.21). In the whole new dataset for adults (n=481, mean age=22.8 years) no association was detected in either an unadjusted model or adjusting for gender and age. Overall, our results indicate that the association between winter SOB and increased subclinical psychosis may hold in children, but does not in the broad general adult population. Nevertheless, the epidemiological and clinicopathological significance of winter SOB as a risk factor for subclinical psychosis would probably be slight due to the small effect sizes indicated by the reports available to date.

The associations of month of birth with body mass index, waist circumference, and leg length: findings from the China Kadoorie Biobank of 0.5 million adults

Background

Season of birth (SoB) has been linked with various health outcomes. This study aimed to examine the associations between month of birth (MoB) and adult measures of leg length (LL), body mass index (BMI), and waist circumference (WC).

Methods

We analysed survey data from 10 geographically diverse areas of China obtained through the China Kadoorie Biobank. Analysis included 487 529 adults with BMI ≥ 18.5 kg/m². A general linear model was used to examine the associations between MoB and adult measures of LL, BMI, and WC, adjusted for survey site, sex, age, education level, smoking habit, alcohol consumption, physical activity level, sedentary leisure time, height (only for WC and LL), and hip circumference (only for LL).

Results

MoB was independently associated with both BMI and WC. Birth months in which participants had higher measures of adiposity were March–July for BMI and March–June for WC. The peak differences were 0.14 kg/m² for BMI and 0.47 cm for WC. The association between MoB and LL depended on survey site. Participants who were born in February–August in four sites (Harbin, Henan, Gansu, and Hunan) had the shortest LL (all P < 0.01). The peak difference in mean LL was 0.21 cm. No statistically significant association between MoB and LL was noted in the other sites (Qingdao, Suzhou, Sichuan, Zhejiang, Liuzhou, and Haikou).

Conclusions

These findings suggest that MoB is associated with variations in adult adiposity measures and LL among Chinese adults. Low exposure to ultraviolet B radiation and subsequent reduced levels of vitamin D during the late second and early third trimesters may be involved in these phenomena.

Prenatal factors associated with the neonatal line thickness in human deciduous incisors

The neonatal line (NNL) is used to distinguish developmental events observed in enamel which occurred before and after birth. However, there are few studies reporting relationship between the characteristics of the NNL and factors affecting prenatal conditions. The aim of the study was to determine prenatal factors that may influence the NNL thickness in human deciduous teeth. The material consisted of longitudinal ground sections of 60 modern human deciduous incisors obtained from full-term healthy children with reported birth histories and prenatal factors. All teeth were sectioned in the labio-lingual plane using diamond blade (Buechler IsoMet 1000). Final specimens were observed using scanning electron microscopy at magnifications 320×. For each tooth, linear measurements of the NNL thickness were taken on its labial surface at the three levels from the cemento-enamel junction. The difference in the neonatal line thickness between tooth types and between males and females was statistically significant. A multiple regression analyses confirmed influence of two variables on the NNL thickness standardised on tooth type and the children's sex (z-score values). These variables are the taking of an antispasmodic medicine by the mother during pregnancy and the season of the child's birth. These two variables together explain nearly 17% of the variability of the NNL. Children of mothers taking a spasmolytic medicine during pregnancy were characterised by a thinner NNL compared with children whose mothers did not take such medication. Children born in summer and spring had a thinner NNL than children born in winter. These results indicate that the prenatal environment significantly contributes to the thickness of the NNL influencing the pace of reaching the post-delivery homeostasis by the newborn's organism.

Season of birth in suicides: excess of births during the summer among schizophrenic suicide victims

BACKGROUND

Season of birth is associated with several psychiatric disorders and suicidal behavior. We explored the association between the season of birth and suicide among schizophrenic and psychotic suicide victims.

METHODS

The study sample consisted of all suicides in the province of Oulu in Northern Finland from 1989 to 2010. Causes of death were extracted from death certificates, and psychiatric diagnoses associated with the hospital treatments were obtained from the Finnish Hospital Discharge Register. The seasons were defined as follows: winter (from November to January), spring (from February to April), summer (from May to July), and autumn (from August to October). Suicide victims (n = 1,902) were categorized as having either schizophrenia (n = 228) or psychosis other than schizophrenia (n = 240). Suicide victims without any hospital-treated mental disorder (n = 1,434) were used as a comparison group.

RESULTS

The distribution of births among suicide victims with schizophrenia differed statistically significantly from that observed in the general population, with a peak in summer (OR 1.2, 95% CI 1.0-1.5).

CONCLUSIONS

Birth during summer may predispose schizophrenic persons to suicide. The putative roles of serotonin, dopamine, and vitamin D status in the season of birth of psychotic suicide victims are discussed.

Early-life nutritional programming of longevity

Available data from both experimental and epidemiological studies suggest that inadequate diet in early life can permanently change the structure and function of specific organs or homoeostatic pathways, thereby ‘programming’ the individual’s health status and longevity. Sufficient evidence has accumulated showing significant impact of epigenetic regulation mechanisms in nutritional programming phenomenon. The essential role of early-life diet in the development of aging-related chronic diseases is well established and described in many scientific publications. However, the programming effects on lifespan have not been extensively reviewed systematically. The aim of the review is to provide a summary of research findings and theoretical explanations that indicate that longevity can be influenced by early nutrition.

Multiple sclerosis in South America: month of birth in different latitudes does not seem to interfere with the prevalence or progression of the disease

OBJECTIVE

To assess whether the month of birth in different latitudes of South America might influence the presence or severity of multiple sclerosis (MS) later in life.

METHODS

Neurologists in four South American countries working at MS units collected data on their patients' month of birth, gender, age, and disease progression.

RESULTS

Analysis of data from 1207 MS patients and 1207 control subjects did not show any significant variation in the month of birth regarding the prevalence of MS in four latitude bands (0-10; 11-20; 21-30; and 31-40 degrees). There was no relationship between the month of birth and the severity of disease in each latitude band.

CONCLUSION

The results from this study show that MS patients born to mothers who were pregnant at different Southern latitudes do not follow the seasonal pattern observed at high Northern latitudes.

Higher relative risk for multiple sclerosis in a pediatric and adolescent diabetic population: analysis from DPV database

OBJECTIVE Type 1 diabetes and multiple sclerosis (MS) are typical autoimmune diseases in children and young adults. We assessed the co-occurrence of type 1 diabetes and MS by estimating the relative risk (RR) for MS in a pediatric and adolescent diabetic population and looked for possible influencing factors. RESEARCH DESIGN AND METHODS Within the Diabetes Patienten Verlaufsdokumentation (DPV)-Wiss Project, from January 1995 to October 2012, data from 56,653 patients with type 1 diabetes were collected in 248 centers in Germany and Austria. Published data on German and Mid-European MS prevalence were taken for comparison. Multivariable regression analysis was used to identify confounders for co-occurrence of type 1 diabetes and MS. RESULTS The RR for MS in patients with type 1 diabetes was estimated at 3.35-4.79 (95% CI 1.56-7.21 and 2.01-11.39, respectively). Immigration status in all patients (P < 0.05) and the presence of thyroid antibodies in male patients only (P = 0.05) were identified as influencing factors on MS incidence within the DPV database. The month-of-birth pattern revealed that risk was higher during the spring and summer months in the population with type 1 diabetes and MS in comparison with the population with type 1 diabetes. CONCLUSIONS The present cohort study demonstrates a higher risk of co-occurrence of MS in a pediatric and adolescent diabetic population. Immigration status and thyroid antibodies in male patients were independent risk indicators for the incidental rate of MS. Diabetic patients born during spring and summer had a higher risk for the development of MS. We suggest that environmental factors modulate the individual's risk for the co-occurrence of both diseases.

Perinatal programming of neuroendocrine mechanisms connecting feeding behavior and stress

Feeding behavior is closely regulated by neuroendocrine mechanisms that can be influenced by stressful life events. However, the feeding response to stress varies among individuals with some increasing and others decreasing food intake after stress. In addition to the impact of acute lifestyle and genetic backgrounds, the early life environment can have a life-long influence on neuroendocrine mechanisms connecting stress to feeding behavior and may partially explain these opposing feeding responses to stress. In this review I will discuss the perinatal programming of adult hypothalamic stress and feeding circuitry. Specifically I will address how early life (prenatal and postnatal) nutrition, early life stress, and the early life hormonal profile can program the hypothalamic-pituitary-adrenal (HPA) axis, the endocrine arm of the body's response to stress long-term and how these changes can, in turn, influence the hypothalamic circuitry responsible for regulating feeding behavior. Thus, over- or under-feeding and/or stressful events during critical windows of early development can alter glucocorticoid (GC) regulation of the HPA axis, leading to changes in the GC influence on energy storage and changes in GC negative feedback on HPA axis-derived satiety signals such as corticotropin-releasing-hormone. Furthermore, peripheral hormones controlling satiety, such as leptin and insulin are altered by early life events, and can be influenced, in early life and adulthood, by stress. Importantly, these neuroendocrine signals act as trophic factors during development to stimulate connectivity throughout the hypothalamus. The interplay between these neuroendocrine signals, the perinatal environment, and activation of the stress circuitry in adulthood thus strongly influences feeding behavior and may explain why individuals have unique feeding responses to similar stressors.