Duration of gestation, size at birth and later childhood behaviour

Impaired head circumference growth and behavioural problems in childhood: Longitudinal findings from the MINA-Brazil birth cohort

BACKGROUND

Previous evidence on the relation between early head circumference (HC) growth and behavioural outcomes in preschoolers has been inconsistent.

OBJECTIVE

We aimed to investigate whether HC growth from birth to 5 years of age was related to internalising or externalising behavioural problems at 5 years of age in a sex-specific manner.

METHODS

Among 303 girls and 318 boys from the MINA-Brazil birth cohort, we examined the associations between changes in HC from birth to 5 years of age and internalising and externalising behaviour problem scores at 5 years according to the Strengths and Difficulties Questionnaire for parents. HC values were transformed into sex- and age-specific z-scores (HCZ) using World Health Organisation standards, and the differences between values at 5 years of age and birth were classified into quintiles. We estimated adjusted mean differences with 95% confidence intervals in behavioural problem scores between HCZ change quintiles using multivariable linear regression by sex. To examine nonlinear associations, we included cubic spline terms.

RESULTS

Head circumference growth from birth to 5 years of age was inversely and nonlinearly associated with internalising problems in girls. Compared with girls at the lowest quintile of HC growth, those above had an adjusted 1.27 (95% confidence interval 0.28, 2.27) points lower mean internalising problems score. This association was mostly driven by HC growth during the first 2 years. We found no association between HC growth and externalising behaviour in either sex.

CONCLUSIONS

Impaired HC growth was related to higher mean internalising problem scores at 5 years of age in girls but not in boys. HC growth was not associated with externalising problems.

Effects of antenatal micronutrient supplementation regimens on adolescent emotional and behavioral problems: A 14-year follow-up of a double-blind, cluster-randomized controlled trial

BACKGROUND & AIMS

Antenatal multiple micronutrient supplementation has been shown to have beneficial effects on birth outcomes and may improve child development. However, whether there is an effect of antenatal micronutrient supplementation strategies on offspring socioemotional outcomes remains unknown. We aimed to examine the effect of antenatal folic acid (FA), iron-folic acid (IFA), and multiple micronutrient (MMN) supplementation on adolescent emotional and behavioral outcomes.

METHODS

We conducted a double-blind, cluster-randomized trial of antenatal micronutrient supplementation in rural western China between 2002 and 2006. Pregnant females were randomized by village to receive either daily (i) 400 μg FA, (ii) IFA containing 60 mg iron and 400 μg FA or (iii) MMN supplementation containing 30 mg iron, 400 μg FA plus 13 additional vitamins and minerals. A 14-year follow-up of their offspring was conducted in 2016. Adolescents were administered the locally adapted Youth Self-Report-2001 (YSR-2001) which produced internalizing, externalizing, and total behavior problem scores. We applied generalized estimating equations to assess the effect of the randomized regimens on YSR-2001 scores and explored the potential effect modification by household wealth and initial timing and duration of supplementation.

RESULTS

A total of 1920 adolescents were included in the analysis, 1130 (58.9%) were male, and the mean (SD) age was 11.8 (0.78) years. Adolescents in IFA group had lower total (mean difference (MD): -2.89; 95% CI -5.73, -0.04) and externalizing (MD: -0.97; 95% CI -1.79, -0.15) problem scores as compared to those in FA group. There was no effect of MMN on behavior problem scores as compared to IFA and FA alone. Although, in effect modification analyses, MMN appeared to have greater beneficial effects in wealthier households than IFA and FA alone.

CONCLUSIONS

Iron supplementation during pregnancy reduced adolescent emotional and behavioral problem scores which provides additional support for expanding coverage of iron-containing prenatal supplements in resource-limited settings.

TRIAL REGISTRATION

isrctn. org Identifier: ISRCTN08850194.

Implications for quantifying early life growth trajectories of term-born infants using INTERGROWTH-21st newborn size standards at birth in conjunction with World Health Organization child growth standards in the postnatal period

BACKGROUND

The INTERGROWTH-21st sex and gestational age (GA) specific newborn size standards (IG-NS) are intended to complement the World Health Organization Child Growth Standards (WHO-GS), which are not GA-specific. We examined the implications of using IG-NS at birth and WHO-GS at postnatal ages in longitudinal epidemiologic studies.

OBJECTIVES

The aim of this study was to quantify the extent to which standardised measures of newborn size and growth are affected when using WHO-GS versus IG-NS at birth among term-born infants.

METHODS

Data from two prenatal trials in Bangladesh (n = 755) and The Gambia (n = 522) were used to estimate and compare size at birth and growth from birth to 3 months when using WHO-GS only ('WHO-GS') versus IG-NS at birth and WHO-GS postnatally ('IG-NS'). Mean length-for-age (LAZ), weight-for-age (WAZ) and head circumference-for-age (HCAZ), and the prevalence of undernutrition (stunting: LAZ < -2SD; underweight: WAZ < -2SD; and microcephaly: HCAZ < -2SD) were estimated overall and by GA strata [early-term (370/7 -386/7 ), full-term (390/7 -406/7 ) and late-term (410/7 -430/7 )]. We used Bland-Altman plots to compare continuous indices and Kappa statistic to compare categorical indicators.

RESULTS

At birth, mean LAZ, WAZ and HCAZ, and the prevalence of undernutrition were most similar among newborns between 39 and 40 weeks of GA when using WHO-GS versus IG-NS. However, anthropometric indices were systematically lower among early-term infants and higher among late-term infants when using WHO-GS versus IG-NS. Early-term and late-term infants demonstrated relatively faster and slower growth, respectively, when using WHO-GS versus IG-NS, with the direction and magnitude of differences varying between anthropometric indices. Individual-level differences in attained size and growth, when using WHO-GS versus IG-NS, were greater than 0.2 SD in magnitude for >60% of infants across all anthropometric indices.

CONCLUSIONS

Using IG-NS at birth with WHO-GS postnatally is acceptable for full-term infants but may give a misleading interpretation of growth trajectories among early- and late-term infants.

Gestational Age, Birth Weight, and Neurocognitive Development in Adolescents in Tanzania

OBJECTIVES

To investigate the association between gestational age, birthweight, and birthweight adjusted for gestational age, with domains of neurocognitive development and behavioral problems in adolescents in Tanzania.

STUDY DESIGN

Data from a long-term follow-up of adolescents aged 11-15 years born to women previously enrolled in a randomized controlled trial of prenatal multiple micronutrient supplementation in Dar es Salaam, Tanzania, were used. A battery of neurodevelopmental tests were administered to measure adolescent general intelligence, executive function, and behavioral problems. The INTERGROWTH-21st newborn anthropometric standards were used to derive birthweight for gestational age z-scores. We assessed the shape of relationships using restricted cubic splines and estimated the associations of gestational age, birthweight, and birthweight for gestational age z-score with adolescent development using multivariable linear regressions.

RESULTS

Among adolescents studied (n = 421), higher gestational age (per week), birthweight (per 100 grams), and birthweight for gestational age z-score (per SD) were linearly associated with higher intelligence score (adjusted standardized mean difference, 0.05 SD [95% CI, 0.01-0.09], 0.04 SD [95% CI, 0.02-0.06], and 0.09 SD [95% CI, 0.01-0.17], respectively). Birthweight and birthweight for gestational age z-score, but not gestational age, were also associated with improved executive function. Low birthweight (<2500 g) was associated with lower intelligence and executive function scores. Associations between birthweight and executive function were stronger among adolescents born to women with higher education.

CONCLUSIONS

The duration of gestation and birthweight were positively associated with adolescent neurodevelopment in Tanzania. These findings suggest that interventions to improve birth outcomes may also benefit adolescent cognitive function.

Birth weight rather than birth length is associated with childhood behavioural problems in a Czech ELSPAC cohort

Many physical and psychological characteristics are influenced by prenatal development. Some studies have located links between low birth parameters and behavioural problems, with the latter in turn associated with educational progress, career success, overall health, and subsequent life events. However, few studies have investigated whether this association also applies to children in the normal birth growth range. This study thus investigates the relationship between normal-range birth length, weight, and behavioural problems at the age of seven. We use data from the Czech part of the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) cohort, which provides comprehensive insight into a post-communist country undergoing a period of economic transition. Childhood behavioural problems were measured in 1,796 children using the Strengths and Difficulties Questionnaire. Associations were modelled using weighted logistic regression. Birth weight was found to be linked to the total difficulties score, hyperactivity, and peer relationship problems subscales in a fully adjusted model while birth length was not significantly associated with any subscale in the fully adjusted model. We thus conclude that normal-range birth weight is associated with behavioural problems. It can therefore be assumed that the odds of behavioural problems and their consequences can be mitigated by preventive programs targeting pregnant women and children with lower but still normal weight.

Early-term elective Caesarean sections did not increase the risk of behavioural problems at six to eight years of age

AIM

Our aim was to explore the under-researched associations between an elective Caesarean section (C-section) at early-term or full-term gestation and behaviour at 6-8 years of age.

METHODS

We identified 1220 eligible children born by elective C-sections at Danish hospital from 2009 to 2011. Their mothers were randomised to elective C-sections at either 38+3 (early-term) or 39+3 (full-term) weeks of gestation. From December 2017 to August 2018, the parents completed the Strengths and Difficulties Questionnaire. The results were adjusted for maternal education, parity and the child's sex.

RESULTS

Of the 574 (45%) children followed up, 288 were delivered early-term and 286 were delivered full-term. The groups had similar baseline characteristics. There were no differences in the total difficulties score, subscale scores or the risk of being classified as having a possible or probable psychiatric disorder. Early-term boys had a lower risk of being classified as having a possible or probable psychiatric disorder and early-term girls had higher risk, but the results were not statistically significant.

CONCLUSION

We found no difference in behaviour at 6-8 years of age between children born by elective C-section at early- versus full-term gestation.

Adaptive Behavioral, Social-Emotional, and Neurodevelopmental Outcomes at 2 Years of Age in Hungarian Preterm Infants Based on Bayley III

AIM

 This study aimed to assess cognitive, language, and motor development as well as social-emotional and adaptive behavior skills of low birthweight (LBW) children.

METHODS

Our cohort contained 305 two-year-old LBW children. Developmental functioning was assessed by the Bayley Scales of Infant and Toddler Development, 3^rd Edition.

RESULTS

Performance in language, particularly in expressive communication was the poorest. Extremely low birthweight (ELBW) children were found to be at increased risk of developmental delay: 12.73 times in motor (95%CI = 2.8-57.5), 9.81 times in cognitive (95%CI = 3.2-29.6) and 3.91 times in language (95%CI = 1.6-9.4), and social-emotional skills (95%CI = 1.6-9.5). Parents of children with lower birthweight reported poorer social and practical adaptive skills. Self-care domain seemed to be the least developed.

CONCLUSION

Additionally, the screening for developmental delays, monitoring the adaptive behavior skills may also be useful - especially among ELBW children - in order to identify the specific areas, situations, and functions that are most in need of interventions.

ABBREVIATIONS

AB: Adaptive Behavior; ABAS-II: Adaptive Behavior Assessment System-II; BPD: Bronchopulmonary Dysplasia; BSID-III: Bayley Scales of Infant Development 3^rd Edition; BW: Birthweight; CI: Confidence Interval; CS: Composite Score; ELBW: Extremely Low Birthweight; GA: Gestational Age; IVF: In Vitro Fertilization; IVH: Intraventricular Hemorrhage; LBW: Low Birthweight; NEC: Necrotizing Enterocolitis; OR: Odds Ratio; ROP: Retinopathy of Prematurity; SE: Social-Emotional Development; VLBW: Very Low Birthweight.

Dietary intake and food sources of one-carbon metabolism nutrients in preschool aged children

BACKGROUND

It is hypothesised that epigenetic mechanisms including DNA methylation may underlie the relationship between early-life nutrition and child cognitive outcomes. This study aimed to identify dietary patterns associated with the intake of one-carbon metabolism nutrients in children aged 2-3 years.

METHODS

A validated 120-item semi-quantitative food frequency questionnaires at 2-3 years of age were used to estimate the intake of one-carbon metabolism nutrients (methionine, folate, choline and vitamins B2, B6, B12) and to quantify mean number of serves consumed of the food groups specified by the Australian Guide to Healthy Eating (AGHE). Descriptive statistics were used to analyse the contribution of each food group and food items to the total intake of one-carbon metabolism nutrients. Linear regression was used to test for linear trends in food group servings by nutrient intake quintiles.

RESULTS

No child (n = 60) from the Women And Their Children's Health (WATCH) study consumed the recommended number of serves for all AGHE food groups. Dairy and alternatives (18-44%), discretionary foods (6-33%) and meat and alternatives (6-31%) were the main sources of most one-carbon metabolism nutrients. Most child intakes of one-carbon metabolism nutrients exceeded the nutrient reference values (NRVs), except for the intake of choline, for which the mean intake was 9% below the adequate intake (AI).

CONCLUSION

Dairy and alternatives, discretionary foods and meat and alternatives food groups contributed significantly to the children's intake of one-carbon metabolism nutrients. The children generally had low intakes of meat and alternative foods, which may explain their inadequate intake of choline.

Tobacco exposure and maternal psychopathology: Impact on toddler problem behavior

Prenatal exposure to tobacco has consistently predicted later problem behavior for children. However, little is known about developmental mechanisms underlying this association. We examined a conceptual model for the association between prenatal tobacco exposure and child problem behavior in toddlerhood via indirect paths through fetal growth, maternal depression, and maternal aggressive disposition in early infancy and via maternal warmth and sensitivity and infant negative affect in later infancy. The sample consisted of 258 mother-child dyads recruited during pregnancy and assessed periodically at 2, 9, and 16months of child age. Pathways via maternal depression and infant negative affect to toddler problem behavior were significant. Further, combined tobacco and marijuana exposure during pregnancy and reduced fetal growth also demonstrated important associations with infant negative affect and subsequent problem behavior. These results highlight the importance of considering the role of maternal negative affect and poor fetal growth as risk factors in the context of prenatal exposure.

Prenatal cannabis exposure - The "first hit" to the endocannabinoid system

As more states and countries legalize medical and/or adult recreational marijuana use, the incidences of prenatal cannabis exposure (PCE) will likely increase. While young people increasingly view marijuana as innocuous, marijuana preparations have been growing in potency in recent years, potentially creating global clinical, public health, and workforce concerns. Unlike fetal alcohol spectrum disorder, there is no phenotypic syndrome associated with PCE. There is also no preponderance of evidence that PCE causes lifelong cognitive, behavioral, or functional abnormalities, and/or susceptibility to subsequent addiction. However, there is compelling circumstantial evidence, based on the principles of teratology and fetal malprogramming, suggesting that pregnant women should refrain from smoking marijuana. The usage of marijuana during pregnancy perturbs the fetal endogenous cannabinoid signaling system (ECSS), which is present and active from the early embryonic stage, modulating neurodevelopment and continuing this role into adulthood. The ECSS is present in virtually every brain structure and organ system, and there is also evidence that this system is important in the regulation of cardiovascular processes. Endocannabinoids (eCBs) undergird a broad spectrum of processes, including the early stages of fetal neurodevelopment and uterine implantation. Delta-9-tetrahydrocannabinol (THC), the psychoactive chemical in cannabis, enters maternal circulation, and readily crosses the placental membrane. THC binds to CB receptors of the fetal ECSS, altering neurodevelopment and possibly rewiring ECSS circuitry. In this review, we discuss the Double-Hit Hypothesis as it relates to PCE. We contend that PCE, similar to a neurodevelopmental teratogen, delivers the first hit to the ECSS, which is compromised in such a way that a second hit (i.e., postnatal stressors) will precipitate the emergence of a specific phenotype. In summary, we conclude that perturbations of the intrauterine milieu via the introduction of exogenous CBs alter the fetal ECSS, predisposing the offspring to abnormalities in cognition and altered emotionality. Based on recent experimental evidence that we will review here, we argue that young women who become pregnant should immediately take a "pregnant pause" from using marijuana.

Associations Between Gestational Age at Birth and Alcohol Use in the Avon Longitudinal Study of Parents and Children

BACKGROUND

The relationship between gestational age at birth (GA) and alcohol use measures in early adulthood was examined in a large U.K. community-based birth cohort (Avon Longitudinal Study of Parents and Children).

METHODS

A series of linear and logistic regression models were used to test for main effects of a continuous measure of GA on a range of alcohol use measures, and moderation of these associations by sex. In addition, mediation analyses assessed the extent to which significant associations between GA and alcohol use operated indirectly, through influences of the parental environment and/or childhood measures of emotional and behavioral health (EBH).

RESULTS

Earlier GA significantly predicted never drinking by age 18, but was not associated with other measures of alcohol use behavior among young adult drinkers (i.e., Self-Rating of the Effects of Alcohol, Alcohol Use Disorders Identification Test, or DSM-IV-TR Criteria for Alcohol Dependence). The association between earlier GA and never drinking by age 18 was moderated by sex, such that females born early were less likely to have ever had a drink by age 18. In the full sample, childhood measures of EBH were found to mediate the association between earlier GA and never drinking by age 18. This association was not mediated by parenting factors.

CONCLUSIONS

Earlier GA is associated with never drinking alcohol in early adulthood, in females. Emotional and behavioral difficulties experienced in early childhood may mediate the relationship between earlier GA and never drinking by age 18.

Attention problems in relation to gestational age at birth and smallness for gestational age

BACKGROUND

While it is well established that very preterm birth (gestational age at birth <32 weeks) is related to increased attention problems, there is still considerable uncertainty of the effects of moderate or late preterm birth or smallness for gestational age (SGA) on attention regulation.

AIMS

To investigate the impact of gestational age at birth and SGA, birth on child attention problems.

STUDY DESIGN

Prospective longitudinal cohort study.

SUBJECTS

A total of 1435 children sampled from the Bavarian Longitudinal Study (BLS).

OUTCOME MEASURES

Main outcome variables were parent-reported attention problems and examiner-reported attention skills at 6 and 8 years. Predictors were linked to attention outcomes using hierarchical regression analyses.

RESULTS

Gestational age at birth ranged from 25 weeks to 41 weeks. We found a quadratic effect of gestational age on attention problems (β6 years=0.161, 95% CI=0.085; 0.236; β8 years=0.211, 95% CI=0.135; 0.287), and attention skills at 6 and 8 years (β6 years=-0.178, 95% CI=-0.252; -0.104; β8 years=-0.169, 95% CI=-0.243; -0.094). Elective caesarean birth did not predict child attention. In adjusted models, SGA was an additional risk factor for attention problems (β=0.080, 95% CI=0.026; 0.134), and attention skills (β=-0.091, 95% CI=-0.143; -0.039) at 6 years but not at 8 years after adjusting for child sex and family SES.

CONCLUSION

Adverse effects on attention are disproportionately higher at early gestations. In contrast, the impact of SGA status was found to be similar at all gestational ages but disappeared by 8 years.

Birth weight and eating behaviors of young children

OBJECTIVE

To evaluate the relationships prospectively between birth weight (standardized for gestational age) and problematic eating behaviors, as reported by the parents, at different ages in 3 birth cohorts: Generation XXI (Portugal), Avon Longitudinal Study of Parents and Children (United Kingdom), and Etude des Déterminants pre et postnatals précoces du développement et de la santé de l'ENfant study (France) - HabEat project. We also aimed to explore the effect of child's current body mass index (BMI) in these relationships.

STUDY DESIGN

Problematic eating behaviors were assessed at 4-6, 12-15, 24, and 48-54 months, based on caregiver's perception. Children born small, appropriate, and large for gestational age were defined based on sex-specific Kramer growth references. Associations were tested by logistic regression (OR, 95% CI) adjusted for maternal age, education, BMI, smoking, breastfeeding duration, older siblings, birth type and, in a second step, for child's current BMI World Health Organization z-score.

RESULTS

Parents of children born small for gestational age (compared with appropriate gestational age) reported more often feeding difficulties and poor eating patterns (eating small quantities or needing stimulation to eat) at 4-6 months (Generation XXI: OR 2.02, 95% CI 1.40-2.94; Avon Longitudinal Study of Parents and Children: OR 1.36, 95% CI 1.14-1.62; Etude des Déterminants pre et postnatals précoces du développement et de la santé de l'ENfant OR 3.24, 95% CI 1.50-6.96), but this effect was weaker at older ages. Overall, the effects decreased, after adjustment for child's BMI, but remained significant.

CONCLUSIONS

Low birth weight for gestational age was related to later difficulty in eating behaviors, primarily in the first 4-6 months.

Impact of neonatal growth on IQ and behavior at early school age

OBJECTIVES

The objective was to examine associations of neonatal weight gain (NWG) and head circumference gain (HCG) with IQ scores and behavior at early school age.

METHODS

We used data from the Promotion of Breastfeeding Intervention Trial, involving Belarusian infants born full term and weighing ≥2500 g. NWG and HCG were measured as the percentage gain in weight and head circumference over the first 4 weeks relative to birth size. IQ and behavior were measured at 6.5 years of age by using the Wechsler Abbreviated Scales of Intelligence and the Strengths and Difficulties Questionnaire (SDQ), respectively, with SDQ collected from parents and teachers. The associations between the exposures (NWG, HCG) and children's IQ and SDQ were examined by using mixed models to account for clustering of measurements, and adjustment for potentially confounding perinatal and socioeconomic factors.

RESULTS

Mean NWG was 26% (SD 10%) of birth weight. In fully adjusted models, infants in the highest versus lowest quartile of NWG had 1.5-point (95% confidence interval [CI] 0.8 to 2.2) higher IQ scores (n = 13 840). A weak negative (protective) association between NWG and SDQ total difficulties scores was observed for the teacher-reported (β = -0.39, 95% CI -0.71 to -0.08, n = 12 016), but not the parent-reported (β = -0.12, 95% CI -0.39 to 0.15, n = 13 815), SDQ. Similar associations were observed with HCG and IQ and behavior.

CONCLUSIONS

Faster gains in weight or head circumference in the 4 weeks after birth may contribute to children's IQ, but reverse causality (brain function affects neonatal growth) cannot be excluded.

Effect of preterm birth and birth weight on eating behavior at 2 y of age

BACKGROUND

Preterm infants frequently present eating difficulties in early childhood. Determinants of these difficulties are not known.

OBJECTIVE

We assessed the influence of neonatal and maternal characteristics on eating behaviors at 2 y of age.

DESIGN

The following 2 cohorts were compared: 234 preterm children born <33 wk of gestational age from the POLYmorphisme génétique, Nutrition et Comportement Alimentaire cohort and 245 term children from the Observation des Préférences ALImentaires du Nourrisson et de l'Enfant cohort. Eating behaviors were assessed by using the validated Children's Eating Difficulties Questionnaire, which assesses the following 2 dimensions: a low drive to eat and narrow food repertoire. Each dimension was graded from 2 to 10 with more severe difficulties reflected by a higher score. Children in the upper quintile were classified as having eating disorders.

RESULTS

Compared with term children, preterm children had a worse drive-to-eat score (4.3 ± 1.6 compared with 3.6 ± 1.5, respectively; P = 0.001) and a marginally lower food-repertoire score (5.0 ± 1.5 compared with 4.8 ± 1.6, respectively; P = 0.05). In a multilevel logistic regression model, female sex [adjusted OR (aOR): 1.76; 95% CI: 1.08, 2.88; P = 0.025] and birth weight less than -1 z score (aOR: 2.88; 95% CI: 1.47, 5.67; P = 0.002) but not gestational age were associated with a worse drive to eat. A maternal level of education beyond high school was associated with lower risk of a poor food-repertoire score (aOR: 0.54; 95% CI: 0.32, 0.90; P = 0.02).

CONCLUSIONS

Preterm children have more eating difficulties than term children do, but after adjustment for maternal and neonatal characteristics, gestational age is not associated with impaired eating behaviors at the age of 2 y. Female sex, a low maternal level of education, and less than -1 SD intrauterine growth are associated with eating difficulties at 2 y of age. This trial was registered at clinicaltrials.gov as NCT 00663572.

Cohort profile: The promotion of breastfeeding intervention trial (PROBIT)

The PROmotion of Breastfeeding Intervention Trial (PROBIT) is a multicentre, cluster-randomized controlled trial conducted in the Republic of Belarus, in which the experimental intervention was the promotion of increased breastfeeding duration and exclusivity, modelled on the Baby-friendly hospital initiative. Between June 1996 and December 1997, 17,046 mother-infant pairs were recruited during their postpartum hospital stay from 31 maternity hospitals, of which 16 hospitals and their affiliated polyclinics had been randomly assigned to the arm of PROBIT investigating the promotion of breastfeeding and 15 had been assigned to the control arm, in which breastfeeding practices and policies in effect at the time of randomization was continued. Of the mother-infant pairs originally recruited for the study, 16,492 (96.7%) were followed at regular intervals until the infants were 12 months of age (PROBIT I) for the outcomes of breastfeeding duration and exclusivity; gastrointestinal and respiratory infections; and atopic eczema. Subsequently, 13,889 (81.5%) of the children from these mother-infant pairs were followed-up at age 6.5 years (PROBIT II) for anthropometry, blood pressure (BP), behaviour, dental health, cognitive function, asthma and atopy outcomes, and 13,879 (81.4%) children were followed to the age of 11.5 years (PROBIT III) for anthropometry, body composition, BP, and the measurement of fasted glucose, insulin, adiponectin, insulin-like growth factor-I, and apolipoproteins. The trial registration number for Current Controlled Trials is ISRCTN37687716 and that for ClinicalTrials.gov is NCT01561612. Proposals for collaboration are welcome, and enquires about PROBIT should be made to an executive group of the study steering committee (M.S.K., R.M.M., and E.O.). More information, including information about how to access the trial data, data collection documents, and bibliography, is available at the trial website (http://www.bristol.ac.uk/social-community-medicine/projects/probit/).