Maternal pre-pregnancy body mass index explains infant's weight and BMI at 14 months: results from a multi-ethnic birth cohort study

Maternal education and its influence on child growth and nutritional status during the first two years of life: a systematic review and meta-analysis

Background

The first 1000 days of life are critical for a child's health and development. Impaired growth during this period is linked to increased child morbidity, mortality, and long-term consequences. Undernutrition is the main cause, and addressing it within the first 1000 days of life is vital. Maternal education is consistently identified as a significant predictor of child undernutrition, but its specific impact remains to be determined. This study presents a systematic review and meta-analysis investigating the influence of high versus low maternal education levels on child growth from birth to age two, using population-based cohort studies.

Methods

Databases including PubMed, Scopus, EMBASE, Web of Science, ERIC, and Google Scholar were searched from January 1990 to January 2024 using appropriate search terms. We included population-based cohort studies of healthy children aged two years and under and their mothers, categorizing maternal education levels. Child growth and nutritional outcomes were assessed using various indicators. Two reviewers independently conducted data extraction and assessed study quality. The Newcastle Ottawa scale was utilized for quality assessment. Random-effects models were used for meta-analysis, and heterogeneity was assessed using the Cochrane Q and I2 statistic. Subgroup and sensitivity analyses were performed, and publication bias was evaluated.

Findings

The literature search retrieved 14,295 titles, and after full-text screening of 639 reports, 35 studies were included, covering eight outcomes: weight for age z-score (WAZ), height for age z-score (HAZ), BMI for age z-scores (BMIZ), overweight, underweight, stunting, wasting, and rapid weight gain. In middle-income countries, higher maternal education is significantly associated with elevated WAZ (MD 0.398, 95% CI 0.301-0.496) and HAZ (MD 0.388, 95% CI 0.102-0.673) in children. Similarly, in studies with low-educated population, higher maternal education is significantly linked to increased WAZ (MD 0.186, 95% CI 0.078-0.294) and HAZ (0.200, 95% CI 0.036-0.365). However, in high-income and highly educated population, this association is either absent or reversed. In high-income countries, higher maternal education is associated with a non-significant lower BMI-Z (MD -0.028, 95% CI -0.061 to 0.006). Notably, this inverse association is statistically significant in low-educated populations (MD -0.045, 95% CI -0.079 to -0.011) but not in highly educated populations (MD 0.003, 95% CI -0.093 to 0.098).

Interpretation

Maternal education's association with child growth varies based on country income and education levels. Further research is needed to understand this relationship better.

Funding

This study was a student thesis supported financially by Tehran University of Medical Sciences (TUMS).

Prepare Randomized Clinical Trial: Acceptability, Engagement, and Lifestyle Effects of a Weight Loss Intervention Beginning in Pre‐pregnancy

Background

Healthier lifestyles in early pregnancy are associated with lower rates of pregnancy complications, childhood adiposity, and maternal and child cardiovascular risks. However, it is not known whether lifestyle coaching initiated prior to pregnancy can affect behavior and attitudes during pregnancy.

Methods

Three hundred and twenty six women planning pregnancy within 2 years with BMI ≥27 kg/m² were randomized to a behavioral weight loss intervention or to usual care. Analyses reported here examined the intervention’s impact on mid‐pregnancy diet quality and activity levels; program acceptability; and effects of pregnancy on intervention engagement.

Results

One hundred and sixty eight participants experienced pregnancy during the study (intervention: 91; usual care: 77). From randomization to mid‐pregnancy, participants who received the intervention had larger increases in fruit intake than usual care participants (+0.67 vs. +0.06 cups; p = 0.02) and engaged in more vigorous‐intensity activity (3.9 [5.5] vs. 1.2 [3.0] Met‐hr/week p = 0.002) and sports/exercise (17.0 [14.1] vs. 11.0 [9.5] Met‐hr/week; p = 0.03); the groups also differed in changes in sedentary time (−4.9 [15.0] vs. +0.5 [7.6] Met‐hr/week; p = 0.02). Intervention satisfaction was high (>80%), and experiencing pregnancy during the intervention was associated with higher engagement.

Conclusion

A coaching‐based intervention beginning in pre‐pregnancy successfully helped women attain healthier diet and exercise habits in mid‐pregnancy.

Clinical trials registration

Registered with ClinicalTrials.gov, NCT02346162, first registered on January 26, 2015, before date of initial participant enrollment (May 2015), https://clinicaltrials.gov/ct2/show/NCT02346162.

What Links Maternal Prepregnancy BMI to Early Childhood BMI: A Serial Mediation Analysis

OBJECTIVE

The aim of this study was to explore the potential impact of maternal gestational weight gain (GWG), infant birth weight, and postnatal weight change (ΔWAZ) on the relationship between maternal prepregnancy BMI (ppBMI) and childhood BMI.

METHODS

This retrospective cohort study analyzed a data set from Wuhan, China. The mediation effect of targeted mediators on the association between maternal BMI and childhood BMI at the age of 2 years was analyzed.

RESULTS

In the mediation model comprising maternal GWG, infant birth weight, and the first-6-month ΔWAZ as mediators of the association between ppBMI and children's BMI, the per unit increase in ppBMI resulted in a 0.01-kg/m² increase in children's BMI, through all three mediators. For the model comprising infant birth weight and the first-6-month ΔWAZ as mediators but maternal GWG as a moderator, the indirect effects of the first-6-month ΔWAZ on the relationship between ppBMI and childhood BMI was 0.0018 higher when maternal GWG increased from average values to 1 SD above the average values.

CONCLUSIONS

Maternal GWG, infant birth weight, and the first-6-month ΔWAZ mediated the effects of maternal ppBMI on children's BMI. Interventions targeting these factors can mitigate the risk of childhood obesity.

Maternal exposure to a high-fat diet showed unfavorable effects on the body weight, apoptosis and morphology of cardiac myocytes in offspring

OBJECTIVE

The study intends to explore the functions of maternal high-fat diet exposure on progeny weight and heart.

METHODS

Sprague-Dawley (SD) rats, fed on a high-fat diet, were used to establish a model of weight gain before and during pregnancy. The body and cardiac weight of neonatal, 1-month- and 3-month-old rats were measured. The morphology of myocardial cells was observed by hemotoxylin and eosin (H&E) staining. The expression of caspase-3, 8, 9 was measured by qRT-PCR and western blot.

RESULTS

Normal pregnant rats, fed on a high-fat diet throughout pregnancy, had a significant increase in body and cardiac weight of their neonates, and more fat deposition in myocardial cells and an increased expression of caspase-3, 8, 9, compared with that of the normal pregnant rats + normal diet group. These phenomena were relieved through later diet control. Pregnant rats, which fed on a high-fat diet throughout pregnancy, showed more adverse effects on neonatal body and cardiac weight, myocardial cell fat deposition, and the expression of caspase-3, 8, 9, compared with pregnant rats exposed to high-fat diet + normal diet and pregnant rats exposed to high-fat diet + normal diet + exercise. These phenomena cannot be fully restored via controlling later diet.

CONCLUSIONS

Our results stated that a proper diet before and during pregnancy was important for the cardiac health of offspring.

The association between maternal body mass index and child obesity: A systematic review and meta-analysis

BACKGROUND

There is a global obesity crisis, particularly among women and disadvantaged populations. Early-life intervention to prevent childhood obesity is a priority for public health, global health, and clinical practice. Understanding the association between childhood obesity and maternal pre-pregnancy weight status would inform policy and practice by allowing one to estimate the potential for offspring health gain through channelling resources into intervention. This systematic review and meta-analysis aimed to examine the dose-response association between maternal body mass index (BMI) and childhood obesity in the offspring.

METHODS AND FINDINGS

Searches in MEDLINE, Child Development & Adolescent Studies, CINAHL, Embase, and PsycInfo were carried out in August 2017 and updated in March 2019. Supplementary searches included hand-searching reference lists, performing citation searching, and contacting authors. Two researchers carried out independent screening, data extraction, and quality assessment. Observational studies published in English and reporting associations between continuous and/or categorical maternal and child BMI or z-score were included. Categorical outcomes were child obesity (≥95th percentile, primary outcome), overweight/obesity (≥85th percentile), and overweight (85th to 95th percentile). Linear and nonlinear dose-response meta-analyses were conducted using random effects models. Studies that could not be included in meta-analyses were summarised narratively. Seventy-nine of 41,301 studies identified met the inclusion criteria (n = 59 cohorts). Meta-analyses of child obesity included 20 studies (n = 88,872); child overweight/obesity, 22 studies (n = 181,800); and overweight, 10 studies (n = 53,238). Associations were nonlinear and there were significantly increased odds of child obesity with maternal obesity (odds ratio [OR] 3.64, 95% CI 2.68-4.95) and maternal overweight (OR 1.89, 95% CI 1.62-2.19). Significantly increased odds were observed for child overweight/obesity (OR 2.69, 95% CI 2.10-3.46) and for child overweight (OR 1.80, 95% CI 1.25, 2.59) with maternal obesity. A limitation of this research is that the included studies did not always report the data in a format that enabled inclusion in this complex meta-analysis.

CONCLUSIONS

This research has identified a 264% increase in the odds of child obesity when mothers have obesity before conception. This study provides substantial evidence for the need to develop interventions that commence prior to conception, to support women of childbearing age with weight management in order to halt intergenerational obesity.

Association of early pregnancy body mass index and children's birth weight with risk of being overweight in childhood

OBJECTIVES

To examine the potential effects of mothers' early pregnancy body mass index (BMI) and children's birth weight on childhood overweight/obesity at 1-6 years of age.

METHODS

We performed a cohort study in Tianjin, China, using the health care records from the Tianjin maternal and child health care system with 36 719 mother-child pairs from early pregnancy to children at 6 years of age. Logistic regression analyses were used to assess the single and joint associations of maternal early pregnancy BMI and children's birth weight with the risks of children being overweight at 1-6 years of age in multivariable-adjusted models.

RESULTS

Both maternal early pregnancy BMI and children's birth weight were positively associated with the risk of children being overweight at 1-6 years of age. Compared with children who were born to normal weight mothers and had low or normal birth weight (NBW; birth BMI < 85%), higher risks of being overweight at 1-6 years were found among children with low or NBW who were born to overweight mothers, and children with high NBW (BMI ≥ 85%) or macrosomia who were born to normal weight or overweight mothers. Lower risks of being overweight were found among those with low birth weight who were born to normal weight mothers.

CONCLUSIONS

Maternal early pregnancy BMI may play a more important role than children's birth weight in the risk of being overweight from 4 to 6 years of age. Children with high or NBW need to be given more attention to prevent excessive weight gain.

Early life influences on child weight outcomes in the Study to Explore Early Development

We examined associations between child body mass index at 2-5 years and maternal pre-pregnancy body mass index, gestational weight gain, and rapid weight gain during infancy in children with autism spectrum disorder, developmental delays, or population controls. The Study to Explore Early Development is a multi-site case-control study of children, aged 2-5 years, classified as autism spectrum disorder ( n = 668), developmental delays ( n = 914), or population controls ( n = 884). Maternal gestational weight gain was compared to the Institute of Medicine recommendations. Rapid weight gain was a change in weight-for-age z-scores from birth to 6 months > 0.67 standard deviations. After adjusting for case status, mothers with pre-pregnancy overweight/obesity were 2.38 times (95% confidence interval: 1.96-2.90) more likely, and mothers who exceeded gestational weight gain recommendations were 1.48 times (95% confidence interval: 1.17-1.87) more likely, to have an overweight/obese child than other mothers ( P < 0.001). Children with autism spectrum disorder showed the highest frequency of rapid weight gain (44%) and were 3.47 times (95% confidence interval: 1.85-6.51) more likely to be overweight/obese as children with autism spectrum disorder without rapid weight gain ( P < 0.001). Helping mothers achieve a healthy pre-pregnancy body mass index and gestational weight gain represent important targets for all children. Healthy infant growth patterns carry special importance for children at increased risk for an autism spectrum disorder diagnosis.

Relationship Between Maternal Pre-pregnancy Weight and Offspring Weight Strengthens as Children Develop: A Population-Based Retrospective Cohort Study

Background

Maternal pre-pregnancy weight has been reported to be positively associated with offspring weight. The association between maternal weight and offspring weight might be explained by maternal lifestyle. We investigated the strength of the relationship between maternal body mass index (BMI) at the beginning of pregnancy and offspring BMI at several growth stages.

Methods

The source population was all eighth graders registered in all public schools in the city of Fukuroi, Japan, in 2012. Records of maternal anthropometry at the beginning of pregnancy were obtained from the Maternal and Child Health (MCH) Handbook. The height and body weight of each student were measured. A regression model was used to assess the association between maternal BMI z-score at the beginning of pregnancy and offspring BMI z-score at various ages.

Results

Of the source population, data from the MCH Handbook were obtained for 480 students. Among males, maternal BMI z-score was not associated with offspring BMI z-score at birth and at age 3 years but was associated with offspring BMI z-score at age 13 years (standardized regression coefficient (β) = 0.19; P < 0.01). Among females, maternal BMI z-score was associated with offspring BMI z-score at birth (β = 0.11; P < 0.05), at age 3 years (β = 0.22; P < 0.01) and at age 13 years (β = 0.51; P < 0.01).

Conclusions

Our results suggest that the positive association between maternal weight at the beginning of pregnancy and offspring weight around puberty is stronger than that between maternal weight and offspring weight at birth. Maternal lifestyle may influence offspring weight in adolescence.

Maternal prepregnancy BMI or weight and offspring's blood pressure: Systematic review

Emerging evidence suggests that maternal prepregnancy body mass index or weight (MPBW) may be associated with offspring's blood pressure (BP). Therefore, we conducted a systematic review-following the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement-to assess and judge the evidence for an association between MPBW with offspring's later BP. Five data bases were searched without limits. Risk of bias was assessed using the "Tool to Assess Risk of Bias in Cohort Studies," and an evidence grade was allocated following the World Cancer Research Fund criteria. Of 2,011 publications retrieved, 16 studies (all cohort studies) were included in the systematic review; thereof, 5 studies (31%) were rated as good-quality studies. Overall, data from 63,959 participants were enclosed. Systolic BP was analysed in 15 (5 good quality), diastolic BP in 12 (3 good quality), and mean arterial pressure in 3 (no good quality) studies. Five good-quality studies of MPBW with offspring's systolic BP as the outcome and 1 good-quality study with offspring's diastolic BP as the outcome observed a significant association. However, after adding offspring's anthropometry variables to the statistical model, the effect attenuated in 4 studies with systolic BP to nonsignificance, the study with diastolic BP remained significant. No good-quality studies were found with respect to offspring's later mean arterial pressure. In conclusion, this systematic review found suggestive, but still limited, evidence for an association between MPBW with offspring's later BP. The available data suggest that the effect might be mainly mediated via offspring's anthropometry.

Animal models of maternal high fat diet exposure and effects on metabolism in offspring: a meta-regression analysis

Animal models of maternal high fat diet (HFD) demonstrate perturbed offspring metabolism although the effects differ markedly between models. We assessed studies investigating metabolic parameters in the offspring of HFD fed mothers to identify factors explaining these inter-study differences. A total of 171 papers were identified, which provided data from 6047 offspring. Data were extracted regarding body weight, adiposity, glucose homeostasis and lipidaemia. Information regarding the macronutrient content of diet, species, time point of exposure and gestational weight gain were collected and utilized in meta-regression models to explore predictive factors. Publication bias was assessed using Egger's regression test. Maternal HFD exposure did not affect offspring birthweight but increased weaning weight, final bodyweight, adiposity, triglyceridaemia, cholesterolaemia and insulinaemia in both female and male offspring. Hyperglycaemia was found in female offspring only. Meta-regression analysis identified lactational HFD exposure as a key moderator. The fat content of the diet did not correlate with any outcomes. There was evidence of significant publication bias for all outcomes except birthweight. Maternal HFD exposure was associated with perturbed metabolism in offspring but between studies was not accounted for by dietary constituents, species, strain or maternal gestational weight gain. Specific weaknesses in experimental design predispose many of the results to bias.

Maternal BMI, gestational diabetes, and weight gain in relation to childhood obesity: The mediation effect of placental weight

OBJECTIVE

High prepregnancy body mass index (BMI), excessive gestational weight gain (GWG), and gestational diabetes mellitus (GDM) are associated with the risk of childhood obesity. This study aims to examine the extent to which these effects may be mediated through the placenta.

METHODS

Data included 33,893 mothers and their singleton infants from birth to 7 years old (total 154,590 visits) in the Collaborative Perinatal Project, a U.S. multicenter prospective cohort study from 1959 to 1976. The placentas were weighed after removing cord and membranes. We performed sequential generalized estimating equation-linear models excluding and including placental weight to evaluate its mediation effect.

RESULTS

In this population, 21.7% of mothers had overweight or obesity, 17.3% had excessive GWG, and 350 (1%) had diagnosed GDM; in addition, 7.2% children had obesity. After adjustment for prepregnancy BMI and other covariates, childhood BMI was 0.23 (95% CI: 0.05, 0.40) kg/m(2) higher for children born to mothers with GDM versus those without GDM. Inclusion of placental weight in the model attenuated the association by 52% to 0.11 (95% CI: -0.06, 0.28) and similarly attenuated the associations with childhood BMI for GWG by 25% and maternal prepregnancy BMI by 17%.

CONCLUSIONS

Placental weight partly mediates the effects of prepregnancy BMI, excessive GWG, and GDM on childhood BMI.

Fetal growth and subsequent maternal risk of thyroid cancer

Thyroid cancer has peak incidence among women of reproductive age, and growth factors, which have procarcinogenic properties, may play an important etiologic role. However, the association between fetal growth rate during a woman's pregnancy and her subsequent risk of thyroid cancer has not been previously examined. We conducted a national cohort study of 1,837,634 mothers who had a total of 3,588,497 live-births in Sweden in 1973-2008, followed up for thyroid cancer incidence through 2009. There were 2,202 mothers subsequently diagnosed with thyroid cancer in 36.8 million person-years of follow-up. After adjusting for maternal age, height, weight, smoking, and sociodemographic factors, high fetal growth (birth weight standardized for gestational age and sex) was associated with a subsequent increased risk of thyroid cancer in the mother (incidence rate ratio [IRR] per additional 1 standard deviation, 1.05; 95% CI, 1.01-1.09; p = 0.02). Each 1,000 g increase in the infant's birth weight was associated with a 13% increase in the mother's subsequent risk of thyroid cancer (IRR, 1.13; 95% CI, 1.05-1.22; p = 0.001). These findings appeared to involve both papillary and follicular subtypes, and did not vary significantly by the mother's height, weight or smoking status. In this large national cohort study, high fetal growth during a woman's pregnancy was independently associated with a subsequent increased risk of her developing thyroid cancer. If confirmed, these findings suggest an important role of maternal growth factors in the development of thyroid cancer, and potentially may help facilitate the identification of high-risk subgroups of women.

Association between feeding practices and weight status in young children

BACKGROUND

Inappropriate feeding practices during infancy may lead to overweight. The aims of this study are to investigate the growth of children in the first 18 months of life; to evaluate the feeding practices of caregivers using developed Young Child Feeding Questionnaire; and to investigate caregivers' feeding attitudes and behaviors associated with infants' weight status.

METHODS

Six month-old infants and their main caregivers entering the Kongjiang Community Health Center for a routine well-child check were recruited for this study and followed up every 6 months for 12 months. Questionnaire survey was carried out through on-site face-to-face interview at each visit with the main caregivers of children using Young Child Feeding Questionnaire, which included caregivers' feeding attitudes and behaviors. The weight and length of children were measured at each visit.

RESULTS

Among 197 children who completed the investigation at 18 months of age, 64 (32.49%) children were overweight (BMI-for-age z scores > +1). The increases in weight-for-age z scores and BMI-for-age z scores from birth to 6 months, 12 to 18 months and birth to 18 months in overweight children were significantly higher than those in normal weight children (P < 0.001). In normal weight children, caregivers worried more about children's being "underweight" and "eating less" (P = 0.001), whereas caregivers with overweight children worried more about children's "eating too much" and being "overweight" (P < 0.001). In 64 overweight infants, the scores of "concern about child's food intake" were significantly correlated with increase in BAZ between 12 and 18 months (Bata = 0.293, P = 0.029).

CONCLUSIONS

Young Child Feeding Questionnaire is a valid tool for evaluating feeding practice of caregivers. The rapid BMI gain in overweight children may be associated with some inappropriate feeding attitudes and behaviors of caregivers.

Fetal growth and subsequent maternal risk of colorectal cancer

BACKGROUND

High birth weight has been associated with subsequent increased risk of breast cancer in the infant's mother, possibly related to maternal estrogen and growth factor pathways. However, its association with maternal risk of colorectal cancer, the third most common cancer among women, is unknown.

METHODS

We conducted a national cohort study of 1,838,509 mothers who delivered 3,590,523 babies in Sweden in 1973-2008, followed up for colorectal cancer incidence through 2009.

RESULTS

There were 7,318 mothers diagnosed with colorectal cancer in 36.8 million person-years of follow-up. After adjusting for maternal age, body mass index, diabetes, and other potential confounders, high fetal growth was associated with a subsequent increased risk of colorectal cancer in the mother [incidence rate ratio (IRR) per additional 1 SD relative to mean birth weight for gestational age and sex, 1.05; 95% confidence intervals (CI), 1.03-1.07; P < 0.0001]. Each 1,000 g increase in the infant's birth weight was associated with a 12% increase in the mother's subsequent risk of colorectal cancer (IRR, 1.12; 95% CI, 1.07-1.17; P < 0.0001). Multiple gestation was also independently associated with increased maternal risk of colorectal cancer (IRR for twin or higher order vs. singleton, 1.22; 95% CI, 1.04-1.44; P = 0.02).

CONCLUSION

In this large cohort study, high fetal growth and multiple gestation were independently associated with subsequent higher maternal risk of colorectal cancer. These findings warrant further investigation of maternal growth factor and estrogen pathways in the etiology of colorectal cancer.

IMPACT

If confirmed, our findings may help identify subgroups of women at high risk of colorectal cancer.

Relationship between maternal pre-pregnancy body mass index, gestational weight gain and childhood fatness at 6-7 years by air displacement plethysmography

This study aims to investigate the effect of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on offspring body composition. In this prospective cohort study, offspring body composition at 6 years of age was obtained through air displacement plethysmography. Linear regression was used to obtain crude and adjusted coefficients. Information regarding offspring body composition and maternal pre-pregnancy BMI was available for 3156 children and on offspring body composition and GWG for 3129 children. There was a direct association of maternal pre-pregnancy BMI and GWG with offspring's fat mass (FM), fat-free mass (FFM), fat mass index (FMI), fat-free mass index (FFMI) and body fat percent (BF%) in crude and adjusted analyses. After adjustment for co-variables, for each kg m(-2) of maternal pre-pregnancy BMI increase, there was a mean increment of 0.13 kg in the offspring FFM, 0.06 kg m(-2) in FFMI, 0.11 kg in FM, 0.07 kg m(-2) in FMI and 0.18% in BF%. For each kilogram of maternal GWG increase, there was a mean increment of 0.08 kg in offspring's FM, 0.05 kg m(-2) in FMI, 0.04 kg in FFM, 0.01 kg m(-2) in FFMI and 0.18 % in BF%. Mothers with a higher pre-pregnancy BMI or GWG tend to have children with greater adiposity at age 6 years. Fetal overnutrition is more likely among mothers with greater BMI during pregnancy; as a consequence, it can accelerate the childhood obesity epidemic.

Preconception care: nutritional risks and interventions

INTRODUCTION

There is increasingly a double burden of under-nutrition and obesity in women of reproductive age. Preconception underweight or overweight, short stature and micronutrient deficiencies all contribute to excess maternal and fetal complications during pregnancy.

METHODS

A systematic review and meta-analysis of the evidence was conducted to ascertain the possible impact of preconception care for adolescents, women and couples of reproductive age on maternal, newborn and child health (MNCH) outcomes. A comprehensive strategy was used to search electronic reference libraries, and both observational and clinical controlled trials were included. Cross-referencing and a separate search strategy for each preconception risk and intervention ensured wider study capture.

RESULTS

Maternal pre-pregnancy weight is a significant factor in the preconception period with underweight contributing to a 32% higher risk of preterm birth, and obesity more than doubling the risk for preeclampsia, gestational diabetes. Overweight women are more likely to undergo a Cesarean delivery, and their newborns have higher chances of being born with a neural tube or congenital heart defect. Among nutrition-specific interventions, preconception folic acid supplementation has the strongest evidence of effect, preventing 69% of recurrent neural tube defects. Multiple micronutrient supplementation shows promise to reduce the rates of congenital anomalies and risk of preeclampsia. Although over 40% of women worldwide are anemic in the preconception period, only one study has shown a risk for low birth weight.

CONCLUSION

All women, but especially those who become pregnant in adolescence or have closely-spaced pregnancies (inter-pregnancy interval less than six months), require nutritional assessment and appropriate intervention in the preconception period with an emphasis on optimizing maternal body mass index and micronutrient reserves. Increasing coverage of nutrition-specific and nutrition-sensitive strategies (such as food fortification; integration of nutrition initiatives with other maternal and child health interventions; and community based platforms) is necessary among adolescent girls and women of reproductive age. The effectiveness of interventions will need to be simultaneously monitored, and form the basis for the development of improved delivery strategies and new nutritional interventions.

The interleukins IL-6 and IL-1Ra: a mediating role in the associations between BMI and birth weight?

The biological mechanisms in the association between maternal body mass index (BMI) and birth weight are not well understood, but are likely to involve maternal plasma glucose levels and nutrient transport across the placenta, both important modulators of fetal growth. Adipose tissue contributes to circulating levels of interleukins that may affect glucose metabolism and possibly also placental transport of nutrients. We investigated possible mediating roles of Interleukin 6 (IL-6) and Interleukin 1 Receptor antagonist (IL-1Ra) in 208 pregnant women. Known and hypothesized dependencies between BMI in early pregnancy and fasting glucose, IL-1Ra and IL-6 at gestational weeks 30-32, and birth weight were specified in a path diagram. Standardized regression coefficients, expressing direct, indirect and total effects, were estimated by Bayesian path analysis. Mean (s.d.) BMI was 24.9 kg/m2 (4.2) and mean (s.d.) birth weight 3748 g (454). The total effect of BMI on birth weight was 0.24 (95% credibility interval (CrI) [0.12, 0.36]). The direct effect of IL-1Ra on birth weight was not statistically significant, but significant effects of BMI on IL-1Ra (0.61, 95% CrI [0.51, 0.72]), of IL-1Ra on fasting glucose (0.17, 95% CrI [0.01, 0.34]) and of fasting glucose on birth weight (0.14, 95% CrI [0.01, 0.27]) implied an indirect pathway from BMI via IL-1Ra on birth weight. Approximately 20% of the effect of BMI on birth weight was mediated through IL-1Ra. For IL-6, no such effects were found. Our results indicate that IL-1Ra may be a mediator in the association between BMI and birth weight.

Increased maternal BMI is associated with infant wheezing in early life: a prospective cohort study

Rates of obesity are increasing in women of child bearing age with negative impacts on maternal and offspring health. Emerging evidence suggests in utero origins of respiratory health in offspring of obese mothers but mechanisms are unknown. Changes in maternal cortisol levels are one potential factor as cortisol levels are altered in obesity and cortisol is separately implicated in development of offspring wheeze. We aimed to assess whether increased pre-pregnancy maternal body mass index (BMI) was associated with offspring early life wheezing, and whether this was mediated by altered cortisol levels in the mother. In a prospective community-based cohort (Amsterdam Born Children and their Development cohort), women completed questionnaires during pregnancy and at 3-5 months post-delivery regarding self-history of asthma and atopy, and of wheezing of their offspring (n=4860). Pre-pregnancy BMI was recorded and serum total cortisol levels were measured in a subset of women (n=2227) at their first antenatal visit. A total of 20.2% (n=984) women were overweight or obese and 10.3% reported wheezing in their offspring. Maternal BMI was associated with offspring wheezing (1 unit (kg/m2) increase, OR: 1.03; 95% CI: 1.00-1.05), after correction for confounders. Although maternal cortisol levels were lower in overweight mothers and those with a history of asthma, maternal cortisol levels did not mediate the increased offspring wheezing. Pre-pregnancy BMI impacts on baby wheezing, which is not mediated by lower cortisol levels. As the prevalence of obesity in women of child-bearing age is increasing, further studies are needed to investigate modifiable maternal factors to avoid risk of wheezing in young children.

Cesarean delivery and risk of childhood obesity

OBJECTIVE

To investigate whether birth by cesarean delivery rather than vaginal delivery is a risk factor for later childhood obesity.

STUDY DESIGN

Healthy, full-term infants were recruited. Overweight and obesity were defined using measured weight and height according to World Health Organization reference data. Associations between cesarean delivery and being overweight or obese were investigated at age 2, 6, and 10 years (n = 1734, 1244, and 1170, respectively) by multivariate logistic regression models adjusted for socioeconomic status, child characteristics, and maternal prepregnancy characteristics.

RESULTS

Mothers who gave birth by cesarean delivery (∼17%) had a higher mean prepregnancy body mass index (23.7 kg/m(2) vs 22.5 kg/m(2)), greater mean gestational weight gain (15.3 kg vs 14.5 kg), and shorter mean duration of exclusive breastfeeding (3.4 months vs 3.8 months) compared with those who delivered vaginally. The proportion of obese children was greater in the cesarean delivery group compared with the vaginal delivery group at age 2 years (13.6% vs 8.3%), but not at older ages. Regression analyses revealed a greater likelihood of obesity at age 2 years in the cesarean delivery group compared with the vaginal delivery group at age 2 years (aOR, 1.68; 95% CI, 1.10-2.58), but not at age 6 years (aOR, 1.49; 95% CI, 0.55-4.05) or age 10 years (aOR, 1.16; 95% CI, 0.59-2.29).

CONCLUSION

Cesarean delivery may increase the risk of obesity in early childhood. Our results do not support the hypothesis that an increasing rate of cesarean delivery contributes to obesity in childhood.

Prepregnancy Body Mass Index and Feeding Practices in Relation to Infants' Growth

Obesity has now emerged as 1 of the most serious public health problems facing American Indian (AI) children and adolescents. However, little is known about what factors contribute to the early development of obesity in AI children. This study explored the relationships between maternal prepregnancy BMI, feeding practices, and growth in AI infants. The findings of this study highlight the need for nurse midwives and pediatric nurse practitioners to increase AI mothers' awareness about their feeding practices, exclusive breastfeeding, and timing for solid food introduction.

Migrant background and weight gain in early infancy: results from the German study sample of the IDEFICS study

OBJECTIVE

To examine variations in infant weight gain between children of parents with and without migrant background and to investigate how these differences are explained by pre- and perinatal factors.

METHODS

We used data on birth weight and weight at six months from well-child check-up books that were collected from a population-based German sample of children in the IDEFICS study (n = 1,287). We calculated unadjusted and adjusted means for weight z-scores at birth and six months later. We applied linear regression for change in weight z-score and we calculated odds ratios and 95% confidence intervals (95% CI) for rapid weight gain by logistic regression, adjusted for biological, social and behavioural factors.

RESULTS

Weight z-scores for migrants and Germans differed slightly at birth, but were markedly increased for Turkish and Eastern European infants at age six months. Turkish infants showed the highest change in weight z-score during the first 6 months (ß = 0.35; 95% CI 0.14-0.56) and an increased probability of rapid weight gain compared with German infants. Examination of the joint effect of migrant and socioeconomic status (SES) showed the greatest change in weight z-scores in Turkish infants from middle SES families (ß = 0.77; 95% CI 0.40-1.14) and infants of parents from Eastern European countries with high SES (ß = 0.72; 95% CI 0.13-1.32).

CONCLUSIONS

Our results support the hypothesis that migrant background is an independent risk factor for infant weight gain and suggest that the onset of health inequalities in overweight starts in early infancy.

Placental weight mediates the effects of prenatal factors on fetal growth: the extent differs by preterm status

OBJECTIVE

Elevated pre-pregnancy BMI, excessive gestational weight gain (GWG), and gestational diabetes mellitus (GDM) are known determinants of fetal growth. The role of placental weight is unclear. We aimed to examine the extent to which placental weight mediates the associations of pre-pregnancy BMI, GWG, and GDM with birth weight-for-gestational age, and whether the relationships differ by preterm status.

DESIGN AND METHODS

We examined 1,035 mother-infant pairs at birth from the Boston Birth Cohort. Data were collected by questionnaire and clinical measures. Placentas were weighed without membranes or umbilical cords. We performed sequential models excluding and including placental weight, stratified by preterm status.

RESULTS

We found that 21% of mothers were obese, 42% had excessive GWG, and 5% had GDM. Forty-one percent were preterm. Among term births, after adjustment for sex, gestational age, maternal age, race, parity, education, smoking, and stress during pregnancy, birth weight-for-gestational age z-score was 0.55 (0.30, 0.80) units higher for pre-pregnancy obesity vs. normal weight. It was 0.34 (0.13, 0.55) higher for excessive vs. adequate GWG, 0.67 (0.24, 1.10) for GDM vs. no DM, with additional adjustment for pre-pregnancy BMI. Adding placental weight to the models attenuated the estimates for pre-pregnancy obesity by 20%, excessive GWG by 32%, and GDM by 21%. Among preterm infants, GDM was associated with 0.67 (0.34, 1.00) higher birth weight-for-gestational age z-score, but pre-pregnancy obesity and excessive GWG were not. Attenuation by placental weight was 36% for GDM.

CONCLUSIONS

These results suggest that placental weight partially mediates the effects of pre-pregnancy obesity, GDM, and excessive GWG on fetal growth among term infants.

Maternal "junk food" diet during pregnancy as a predictor of high birthweight: findings from the healthy beginnings trial

BACKGROUND

A high infant birthweight is associated with future risk of a range of adverse health consequences. This study sought to determine whether maternal "junk food" diet (energy-dense, nutrient-poor) predicts high birthweight in first-time mothers in southwest Sydney, Australia.

METHODS

A community-based longitudinal study was conducted with a total of 368 first-time mothers and their newborns. Information about maternal "junk food" diet, including high consumption of soft drink, fast food, and/or processed meat and chips, and self-reported prepregnant weight and height of first-time mothers was collected by a face-to-face interview with mothers between 24 and 34 weeks of pregnancy. Birthweight was measured in hospital and reported by the mother, together with gestational age, when the baby was 6 months old. Logistic regression modeling was used to determine the factors predicting birthweight greater than 4.0 kg.

RESULTS

Eleven percent of newborns weighed more than 4.0 kg (12% boys, 9% girls). Compared with mothers who had a "junk food" diet, mothers who had not consumed "junk food" during pregnancy were significantly less likely to have a newborn weighing more than 4.0 kg, with adjusted odds ratio (AOR) 0.36, 95 percent confidence interval (CI) 0.14-0.91, p = 0.03, after adjusting for maternal weight status and gestational age. Compared with healthy and underweight mothers, overweight or obese mothers were more likely to have a newborn weighing more than 4.0 kg (AOR overweight 3.03, 95% CI 1.35-6.80; obese 3.79, 95% CI 1.41-10.25) after allowing for "junk food" diet and gestational age.

CONCLUSIONS

Maternal "junk food" diet during pregnancy and prepregnant overweight and obesity were independent predictors of high infant birthweight. Early childhood obesity interventions should consider addressing these factors.

The association between maternal serious psychological distress and child obesity at 3 years: a cross-sectional analysis of the UK Millennium Cohort Data

BACKGROUND

  The prevalence of child obesity is increasing rapidly worldwide. Early childhood has been identified as a critical time period for the development of obesity. Maternal mental health and early life environment are crucial factors and have been linked to adverse child outcomes. The objective of the study was to examine the relationship between maternal serious psychological distress and obesity in early childhood.

METHODS

  A cross-sectional analysis of data from the Millennium Cohort Study was conducted. Subjects consisted of all natural mothers (n= 10 465) who had complete and plausible data for Kessler-6 scores, socio-demographic and anthropometric variables, and their children for whom anthropometric measurements were completed at age 3. Maternal serious psychological distress was defined as a score of 13 or more on the Kessler-6 scale. Obesity was defined as body mass index ≥95th centile of the 1990 reference chart for age and sex in children. The data were analysed using spss 16. Maternal socio-demographic factors that are known to influence maternal mental health and child obesity were identified and adjusted using multivariate logistic regression.

RESULTS

  Of the 10 465 mother-child dyads, 3.5% of mothers had serious psychological distress and 5.5% of children were obese at 3 years of age. Logistic regression analysis showed that maternal serious psychological distress was associated with early childhood obesity (P= 0.01; OR 1.62, 95% CI 1.11, 2.37). After adjusting for potential confounding factors using multivariate logistic regression, maternal serious psychological distress remained significantly associated with early childhood obesity (P= 0.01; OR 1.59, 95% CI 1.08, 2.34).

CONCLUSIONS

  The results show that maternal serious psychological distress is independently associated with early childhood obesity.

Feeding and growth of normal birth weight infants during the first year of life in Shanghai

AIM

This study aimed to explore the relationship between infant feeding practices and growth outcomes in the first 12 months of life.

DESIGN

Investigators completed 262 questionnaires, which included infant feeding patterns, feeding environment, feeding beliefs/attitudes and caregivers' feeding behaviors through on-site face-to-face interviews with the main caregivers of infants at 12 months of age. The infant's weight and length at ages 6 and 12 months were measured.

SETTING

The study was conducted in urban Shanghai, China.

SUBJECTS

This study included 262 healthy normal birth weight full-term singleton 6-month-old infants and their main caregivers.

RESULTS

Among 262 infants, 86 (32.82%) infants were overweight [BMI-for-age z scores (BAZ)>+1] at 12 months. Compared with normal weight infants, the overweight infants had higher birth weights (P=0.009). Furthermore, the overweight infants gained significantly more weight (P<0.001) in the first year of life. In normal weight infants, caregivers worried more about infants being "underweight" and "eating less" (P<0.001) whereas caregivers with overweight infants worried more about infants being "overweight" (P<0.001). Consequently, the total score of caregivers' over-feeding behaviors was significantly higher in normal weight infants (P=0.029). However, in overweight infants, the scores of "fed quickly within 10 min" (r=0.223, P=0.039) and "feeding was the best way to stop the infant's fussiness" (r=0.285, P=0.008) were positively correlated with BAZ.

CONCLUSIONS

Overweight in early life is associated with carelessness about excessive appetite and some particular infant feeding behaviors of caregivers in Shanghai.

Misreport of gestational weight gain (GWG) in birth certificate data

Birth certificates are potentially a valuable source of information for studying gestational weight gain (GWG) during pregnancy, particularly important given new Institute of Medicine (IOM) guidelines. We examined factors associated with the accuracy of maternal GWG self-report by linking the gold standard obstetric electronic medical record (EMR) of women from a large urban practice to state birth certificates. Primary outcomes included maternal under-reporting of GWG (>10 lbs below the EMR), accurate reporting (within 10 lbs), and over-reporting (>10 lbs above EMR). Data were stratified across categories of pre-pregnancy body mass index (BMI) and the actual GWG IOM categories (inadequate, adequate, and excessive) acquired in the clinical setting and recorded in the EMR. Among 1,223 women, mean (SD) age was 27.4 (6.2) years, mean (SD) BMI was 28.2 (8.1) kg/m(2), and mean GWG was 26.0 (20.2) pounds. The majority of women with normal BMI (<25 kg/m(2)) and adequate GWG reported GWG accurately (78.8%), more so than any other group. After adjusting for age, race, insurance status, and number of prenatal visits, among women with actual adequate GWG, women with high BMI (≥25 kg/m(2)) were more likely to over-report GWG than women with normal BMI (RR 4.7, 95% CI 2.6-8.4). In patients with normal BMI, women with excessive GWG were more likely to under-report than women with adequate GWG (RR 6.0, 95% CI 3.0-12.1). Such findings raise concern for systematic bias that would limit the use of birth certificate data for studying population trends in GWG.

Maternal triglyceride levels during early pregnancy are associated with birth weight and postnatal growth

OBJECTIVE

To investigate whether randomly sampled maternal total cholesterol (TC) and triglycerides (TG) levels during early pregnancy are associated with birth weight (BW) and postnatal growth.

STUDY DESIGN

Data were derived from the prospective Amsterdam Born Children and their Development cohort study. Randomly sampled TC and TG levels were determined in early gestation (median, 13; IQR, 12-14 weeks). Outcome measures were BW SDS and weight-for-gestational age; postnatal outcome measures were SDS in weight, length, and body mass index during the first year of life (total n = 2502).

RESULTS

The highest TG level was associated with a higher BW SDS (differences 0.20 ± 0.06 between highest and middle quintile; P = .002) and with a higher prevalence (13%) of an infant large for gestational age compared with middle quintile (9%; P = .04). Infants from mothers in the lowest TG quintile had lower SDS in weight, length, and body mass index until age 3 months, and displayed accelerated postnatal growth patterns. Maternal TC was not associated with BW or postnatal growth.

CONCLUSION

High maternal TG levels in the first term of pregnancy were associated with higher BWs and subsequently a higher occurrence of infants large for gestational age, whereas low TG levels were associated with accelerated postnatal growth.

High beverage sugar as well as high animal protein intake at infancy may increase overweight risk at 8 years: a prospective longitudinal pilot study

Background

Combined effects of early exposure to beverage sugar and animal protein and later life overweight risk have not been studied.

Methods

A prospective longitudinal study was initiated in 2001 with 226 infants between 4 and 13 months of age. Dietary intake was assessed with a 2 day food record. Also information on infant body weight and socio-economic status was obtained at baseline. At 8 year follow-up in 2009, children were surveyed again. Main outcome measure was overweight at 8 years as defined by BMIsds > = +1.0. Also maternal BMI, present dietary intake and physical activity, were obtained by questionnaire and 2-day food record.

Results

At the 8 year follow up, 120 children (53%) were surveyed again. Of those, questionnaires and food records were completed for 63 children, for the other 57 children only weight and height at 8 years was available; 20 out of 120 children (17%) were self-reported overweight at 8 years of age. Unadjusted odds ratios (ORs; 95% CI) for overweight at 8 years were 1.10 (1.02, 1.18) for beverage sugar intake per one percent of energy intake and 4.06 (1.50, 11.00) for the highest tertile of animal protein intake at infancy compared to the lowest two tertiles. After adjustment for sex, age, infant weight, breastfed at intake assessment, and socio-economic status, odds ratios were 1.13 (1.03, 1.24) for beverage sugar, and 9.67 (2.56, 36.53) for highest tertile of animal protein intake. In the subgroup with completed questionnaire (n = 63) ORs were also adjusted for current maternal overweight, more than 2 months full breastfeeding, physical activity, and energy intake, but ORs remained significantly associated with overweight at 8 years.

Conclusions

A high intake of sugar containing beverages as well as animal protein in the first year of life may increase the risk of overweight at 8 years. The results of this pilot investigation should be confirmed in a larger cohort.

Overweight at age two years in a multi-ethnic cohort (ABCD study): the role of prenatal factors, birth outcomes and postnatal factors

BACKGROUND

Childhood overweight/obesity is a major public health problem worldwide which disproportionally affects specific ethnic groups. Little is known about whether such differences already exist at an early age and which factors contribute to these ethnic differences. Therefore, the present study assessed possible ethnic differences in overweight at age 2 years, and the potential explanatory role of prenatal factors, birth outcomes and postnatal factors.

METHODS

Data were derived from a multi-ethnic cohort in the Netherlands (the ABCD study). Weight and height data of 3,156 singleton infants at age 2 years were used. Five ethnic populations were distinguished: Dutch native (n = 1,718), African descent (n = 238), Turkish (n = 162), Moroccan (n = 245) and other non-Dutch (n = 793). Overweight status was defined by the International Obesity Task Force guidelines. The explanatory role of prenatal factors, birth outcomes and postnatal factors in ethnic disparities in overweight (including obesity) was assessed by logistic regression analysis.

RESULTS

Compared to the native Dutch (7.1%), prevalence of overweight was higher in the Turkish (19.8%) and Moroccan (16.7%) group, whereas the prevalence was not increased in the African descent (9.2%) and other non-Dutch (8.8%) group. Although maternal pre-pregnancy body mass index partly explained the ethnic differences, the odds ratio (OR) of being overweight remained higher in the Turkish (OR: 2.66; 95%CI: 1.56-4.53) and Moroccan (OR: 2.11; 95%CI: 1.31-3.38) groups after adjusting for prenatal factors. The remaining differences were largely accounted for by weight gain during the first 6 months of life (postnatal factor). Maternal height, birth weight and gender were independent predictors for overweight at age 2 years, but did not explain the ethnic differences.

CONCLUSION

Turkish and Moroccan children in the Netherlands have 2- to 3-fold higher odds for being overweight at age 2 years, which is largely attributed to maternal pre-pregnancy BMI and weight gain during the first 6 months of life. Further study on the underlying factors of this early weight gain is required to tackle ethnic differences in overweight among these children.

Comparison of growth between native and immigrant infants between 0-3 years from the Dutch ABCD cohort

BACKGROUND

In the Netherlands separate reference charts have been developed for native and immigrant groups to deal with differences in growth patterns in later childhood. The use of these charts, however, is complicated by methodological issues; they do not represent all large Dutch immigrant groups in separate charts despite the differences that have been suggested and the evidence of ethnic disparities in growth dates back to 1997.

AIM

Anthropometric measurements from a contemporary multi-ethnic cohort study were created to quantify differences in childhood growth by creating growth charts, separately for boys and girls between the ages of 0-3 years.

SUBJECTS AND METHODS

The infants modelled in the charts had a mother born in the Netherlands (n = 3107), Suriname (n = 225), Turkey (n = 203) and Morocco (n = 336). Charts with and without correction for country of origin of the mother were created by using the LMST method.

RESULTS

All models including the covariate country of origin of the mother fitted the data better (p < 0.0005), but the observed differences were small.

CONCLUSION

Most remarkable differences were found in the BMI and weight measurements for age charts. Especially girls from mothers born in Turkey and Morocco had an increasingly heavier weight for their age than girls from mothers born in the Netherlands.

Overweight and obesity in pregnancy do not adversely affect neonatal outcomes: new evidence

We studied neonatal outcomes of infants of obese mothers in a cohort of 6,125 deliveries, using logistic multivariate analysis to remove the role of potential confounding variables. Although, as in previous reports, the crude unadjusted prevalence of several adverse neonatal outcomes was higher in these infants, the multivariable analysis revealed that only two outcomes remained significantly associated with maternal overweight and obesity: neonatal macrosomia (adjusted odds ratios aOR 1.4, p < 0.001) and meconium aspiration syndrome (aOR 1.6, p = 0.05), indicating that the unadjusted association with the other outcomes was caused by confounding factors. Nonetheless, as macrosomia is associated with increased health risks both to the mothers and their infants, and maternal obesity with considerable maternal morbidity during pregnancy, these results should not lead to complacency, but instead encourage better prevention of obesity in general and during pregnancy in particular.

Maternal prepregnancy body mass index in relation to Hispanic preschooler overweight/obesity

The aim of the current study was to examine the role of maternal prepregnancy body mass index (BMI) on overweight/obesity among US Hispanic children ages 2 and 4 years old. We used US nationally representative data from preschoolers enrolled in the Early Childhood Longitudinal Study-Birth Cohort study. The findings revealed that a significantly higher percent (41.6%) of Hispanic mothers were overweight/obese prior to pregnancy compared to white mothers (34.8%). At 2 years of age, 38.3% of the children born to Hispanic mothers were overweight/obese compared to 29.4% of children born to white mothers. By the age of 4, overweight/obesity increased significantly for both racial/ethnic groups with preschoolers whose mothers were Hispanic being more likely to be overweight/obese (44.6%) compared to children whose mothers were white (34.2%). Further, preschoolers born to overweight/obese Hispanic mothers were more than twice as likely [odds ratio = 2.74 (95% confidence interval (CI) 1.60, 4.69)] to be overweight/obese than those born to Hispanic mothers of normal prepregnancy BMI. Preschoolers born to overweight/obese white mothers were approximately 1.4 (95% CI 1.05, 1.93) times more likely to be overweight/obese in comparison to those born to mothers with a normal prepregnancy BMI. Maternal prepregnancy weight is potentially a modifiable risk factor for preschooler overweight/obesity. Study findings support the design of early and targeted interventions to reduce this risk to the long-term health of Hispanic maternal and child dyads.

Impact of maternal obesity on offspring obesity and cardiometabolic disease risk

The prevalence of obesity among pregnant women is increasing. In addition to the short-term complications of obesity during pregnancy in both mother and child, it is now recognised that maternal obesity has long-term adverse outcomes for the health of her offspring in later life. Evidence from both animal and human studies indicates that maternal obesity increases the risk for the offspring in developing obesity and altering body composition in child- and adulthood and, additionally, it also has an impact on the offspring's cardiometabolic health with dysregulation of metabolism including glucose/insulin homoeostasis, and development of hypertension and vascular dysfunction. Potential mechanisms include effects on the development and function of adipose tissue, pancreas, muscle, liver, the vasculature and the brain. Further studies are required to elucidate the mechanisms underpinning the programming of disease risk in the offspring as a consequence of maternal obesity. The ultimate aim is to identify potential targets, which may be amenable to prevention or early intervention in order to improve the health of this and future generations.

Measuring outcomes in a longitudinal birth cohort

Longitudinal studies are often focussed on specific outcomes to address predetermined hypotheses. Nevertheless, many discoveries have been made with data collected that were not part of the original design. Measurement of a broad range of outcomes is therefore important. Here we describe examples of the types of outcome that a birth cohort should collect, with emphasis on accuracy. We emphasise the use of continuous traits as well as of dichotomous outcomes, using a variety of examples.