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ALSPAC Study Team

Publications and source records attributed to ALSPAC Study Team.

At least 73 records · Page 4Linked to original sources

Amblyopia treatment outcomes after preschool screening v school entry screening: observational data from a prospective cohort study.

BACKGROUND/AIMS: Preschool screening for amblyopia has controversially been abandoned in some localities within the United Kingdom, on the basis that there is no clear evidence of benefit to support its continuation. Data collected within a birth cohort study were used to examine visual outcomes at 7(1/2) years in children who did or did not receive preschool vision screening. METHODS: Monocular logMAR visual acuity with and without a pinhole was assessed by orthoptists. Contemporary records were used to identify children who had been offered and/or received preschool screening. RESULTS: Of 6081 children, 24.9% had been offered preschool screening and 16.7% had attended. The prevalence of amblyopia was approximately 45% lower in the children who received preschool screening than in those who did not (1.1% v 2.0%, p = 0.05). The mean acuity in the worse seeing eyes after patching treatment was better for amblyopic children who received preschool screening than for those who did not; 0.14 v 0.20 logMAR (p <0.001). These effects did not persist in an intention to screen analysis. CONCLUSIONS: Preschool screening at 37 months was associated with an improved treatment outcome for individuals with amblyopia. However, the improvement was clinically small and disappeared when considering all children offered screening rather than only those who received it. Further research is needed into improving the effectiveness of vision screening for preschool children, while in the interim these data do not conflict with current recommendations for school entry screening by orthoptists.

Age Factors↗

Relationship between prenatal infant feeding intention and initiation and duration of breastfeeding: a cohort study.

AIM: To report the relationship between maternal prenatal intention to breastfeed and the actual initiation and duration of breastfeeding. METHODS: Pregnant women resident within Avon, UK, expected to give birth between 1 April 1991 and 31 December 1992 were recruited in a longitudinal cohort study. Main outcome measures included maternal infant feeding intention (breastfeed, breast and bottle feed, bottle feed, or uncertain) at 32 wk of pregnancy: intention in the first week, intention for the rest of the first month and intention in months 2 to 4; initiation and duration of breastfeeding up to six months. RESULTS: Data were available on 10,548 women. Prenatal intention to breastfeed had an influence on both initiation and duration of breastfeeding. Of the women intending to bottle feed from birth, only 3.4% initiated breastfeeding compared with 96.6% of women planning to breastfeed for at least four months. At six months postpartum, the mean duration of breastfeeding for women intending to breastfeed for at least five months was 4.4 mo (95% CI 4.3, 4.4), compared with 2.5 mo (95% CI 2.4, 2.6) for women with a prenatal intention to breastfeed for only one month. Logistic regression, using intended duration as the only explanatory variable, correctly predicted 91.4% of breastfeeding initiation and 72.2% of infant feeding at six months. CONCLUSIONS: This large population-based study confirms the strength of the relationship between maternal prenatal intention to breastfeed and both breastfeeding initiation and duration. Maternal intention was a stronger predictor than the standard demographic factors combined. This should be taken into account in future research, and trials should be undertaken to establish whether interventions could alter maternal intention and thereby increase rates of breastfeeding initiation and duration.

Adult↗

Amblyopia treatment outcomes after screening before or at age 3 years: follow up from randomised trial.

OBJECTIVE: To assess the effectiveness of early treatment for amblyopia in children. DESIGN: Follow up of outcomes of treatment for amblyopia in a randomised controlled trial comparing intensive orthoptic screening at 8, 12, 18, 25, 31, and 37 months (intensive group) with orthoptic screening at 37 months only (control group). SETTING: Avon, southwest England. PARTICIPANTS: 3490 children who were part of a birth cohort study. MAIN OUTCOME MEASURES: Prevalence of amblyopia and visual acuity of the worse seeing eye at 7.5 years of age. RESULTS: Amblyopia at 7.5 years was less prevalent in the intensive group than in the control group (0.6% v 1.8%; P=0.02). Mean visual acuities in the worse seeing eye were better for children who had been treated for amblyopia in the intensive group than for similar children in the control group (0.15 v 0.26 LogMAR units; P<0.001). A higher proportion of the children who were treated for amblyopia had been seen in a hospital eye clinic before 3 years of age in the intensive group than in the control group (48% v 13%; P=0.0002). CONCLUSIONS: The intensive screening protocol was associated with better acuity in the amblyopic eye and a lower prevalence of amblyopia at 7.5 years of age, in comparison with screening at 37 months only. These data support the hypothesis that early treatment for amblyopia leads to a better outcome than later treatment and may act as a stimulus for research into feasible screening programmes.

Age Factors↗

The relationship between Caesarean section and subfertility in a population-based sample of 14 541 pregnancies.

BACKGROUND: There has been a threefold increase in the rate of Caesarean section over the past 25 years. The long-term consequences of Caesarean section may include subsequent subfertility. METHODS: We investigated the relationship between Caesarean section and subfertility within a cohort of 14 541 pregnant women. RESULTS: A history of previous Caesarean section was associated with an increased risk of taking >1 year to conceive from the time of planning a pregnancy, adjusted odds ratio (OR) 1.53 [95% confidence interval (CI) 1.09, 2.14]. This association was stronger for women of parity > or =2, adjusted OR 2.97 (95% CI 1.72, 5.10). Nulliparous women with a history of subfertility were at increased risk of delivery by Caesarean section, adjusted OR 1.56 (1.22, 2.00) and OR 2.33 (1.64, 3.30) for durations of >1 and >3 years respectively. CONCLUSIONS: These findings suggest a complex relationship between Caesarean section and subfertility where subfertility may both precede and be a consequence of Caesarean section.

Cesarean Section↗

Swimming and birth weight.

BACKGROUND: Swimmers can be exposed to high levels of trihalomethanes, byproducts of chlorination disinfection. There are no published studies on the relation between swimming and birth weight. We explored this relation in a large birth cohort, the Avon (England) Longitudinal Study of Parents and Children (ALSPAC), in 1991-1992. METHODS: Information on the amount of swimming per week during the first 18-20 weeks of pregnancy was available for 11,462 pregnant women. Fifty-nine percent never swam, 31% swam up to 1 hour per week, and 10% swam for longer. We used linear regression to explore the relation between birth weight and the amount of swimming, with adjustment for gestational age, maternal age, parity, maternal education level, ethnicity, housing tenure, drug use, smoking and alcohol consumption. RESULTS: We found little effect of the amount of swimming on birth weight. More highly educated women were more likely to swim compared with less educated women, whereas smokers were less likely to swim compared with nonsmokers. CONCLUSIONS: There appears to be no relation between the duration of swimming and birth weight.

Adult↗

Reduced birth weight in boys with hypospadias: an index of androgen dysfunction?

Anthropometric birth measurements analysed for 51 boys with hypospadias identified in a prospective cohort study showed significant reductions in mean values for birth weight, length, and head circumference compared with controls. The absence of the usual sex dimorphism for these variables suggests that the results represent a marker of fetal androgen dysfunction in this subgroup of infants.

Androgens↗

Paracetamol use in pregnancy and wheezing in early childhood.

BACKGROUND: We recently reported links between frequent paracetamol (acetaminophen) use and wheezing and asthma in adults and children, but data are lacking on possible effects of prenatal exposure on wheezing in early childhood. METHODS: In the population based Avon Longitudinal Study of Parents and Children (ALSPAC) women were asked twice during pregnancy (at 18-20 weeks and 32 weeks) about their usage of paracetamol and aspirin. Six months after birth, and at yearly intervals thereafter, mothers were asked about wheezing and eczema symptoms in their child. The effects of paracetamol and aspirin use in pregnancy on the risk in the offspring of wheezing at 30-42 months (n=9,400) and eczema at 18-30 months (n=10,216) and on their risk of different wheezing patterns (defined by presence or absence of wheezing at <6 months and at 30-42 months) were examined. RESULTS: Paracetamol was taken frequently (most days/daily) by only 1% of women. After controlling for potential confounders, frequent paracetamol use in late pregnancy (20-32 weeks), but not in early pregnancy (<18-20 weeks), was associated with an increased risk of wheezing in the offspring at 30-42 months (adjusted odds ratio (OR) compared with no use 2.10 (95% CI 1.30 to 3.41); p=0.003), particularly if wheezing started before 6 months (OR 2.34 (95% CI 1.24 to 4.40); p=0.008). Assuming a causal relation, only about 1% of wheezing at 30-42 months was attributable to this exposure. Frequent paracetamol use in pregnancy was not associated with an increased risk of eczema. Frequent aspirin use in pregnancy was associated with an increased risk of wheezing only at <6 months. CONCLUSIONS: Frequent use of paracetamol in late pregnancy may increase the risk of wheezing in the offspring, although such an effect could explain only about 1% of the population prevalence of wheezing in early childhood.

Acetaminophen↗

Size at birth and early childhood growth in relation to maternal smoking, parity and infant breast-feeding: longitudinal birth cohort study and analysis.

There is remarkably wide variation in rates of infancy growth, however, its regulation is not well understood. We examined the relationship between maternal smoking, parity, and breast- or bottle-feeding to size at birth and childhood growth between 0 and 5 y in a large representative birth cohort. A total of 1,335 normal infants had weight, length/height, and head circumference measured at birth and on up to 10 occasions to 5 y old. Multilevel modeling (MLwiN) was used to analyze longitudinal growth data. Infants of maternal smokers were symmetrically small at birth (p < 0.0005) compared with infants of nonsmokers, however, showed complete catch-up growth over the first 12 mo. In contrast, infants of primiparous pregnancies were thin at birth (p < 0.0005), showed dramatic catch-up growth, and were heavier and taller than infants of nonprimiparous pregnancies from 12 mo onwards. Breast-fed infants were similar in size at birth than bottle-fed infants, but grew more slowly during infancy. Among infants who showed catch-up growth, males caught up more rapidly than females (p = 0.002). In conclusion, early postnatal growth rates are strongly influenced by a drive to compensate for antenatal restraint or enhancement of fetal growth by maternal-uterine factors. The mechanisms that signal catch-up or catch-down growth are unknown but may involve programming of appetite. The importance of nutrition on early childhood growth is emphasized by the marked difference in growth rates between breast- and bottle-fed infants. The sequence of fetal growth restraint and postnatal catch-up growth may predispose to obesity risk in this contemporary population.

Birth Weight↗

Circulating IGF-I levels in childhood are related to both current body composition and early postnatal growth rate.

Rapid infancy growth predicts childhood obesity and earlier rate of maturation. We examined whether early growth rates might also influence levels of hormones relating to growth and weight gain by measuring IGF-I, IGF-II, and leptin levels in 497 normal 5-yr-old children who were followed closely from birth. IGF-I levels at 5 yr were unrelated to cord blood IGF-I levels at birth (r = 0.03; P = 0.7; n = 166) but were positively related to current weight (r = 0.32; P < 0.0005) and height (r = 0.30; P < 0.0005) and inversely related to birthweight (r = -0.21; P < 0.0005). By body composition, IGF-I levels correlated more closely with fat-free mass (r = 0.22; P < 0.0005) than with fat mass (r = 0.12; P < 0.05), whereas leptin (r = 0.57; P < 0.0005) and IGF-II levels (r = 0.15; P < 0.005) correlated more closely with fat mass. Independent of current body composition, IGF-I levels at 5 yr were significantly associated with rate of weight gain between 0-2 yr (beta = 0.19; P < 0.0005), and children who showed postnatal catch-up growth (i.e. those who showed gains in weight or length between 0-2 yr by >0.67 SD score) had higher IGF-I levels than other children (P = 0.02). IGF-II levels at 5 yr were positively related to IGF-II levels at birth (r = 0.17; P = 0.03; n = 166), and leptin levels at 5 yr were mainly related to current adiposity. Circulating IGF-I levels in childhood are influenced by infancy growth rates and possibly mediate the effects of early postnatal nutrition on later rates of growth and maturation.

Aging↗

Alcohol, breastfeeding, and development at 18 months.

OBJECTIVE: We aimed to replicate a previous study of 1-year-olds that reported a deficit in motor development associated with moderate alcohol use during lactation, using a different but comparable population. METHODOLOGY: The mental development of 915 18-month-old toddlers from a random sample of a longitudinal population-based study in the United Kingdom was measured using the Griffiths Developmental Scales. Frequent self-administered questionnaires during and after pregnancy provided maternal data. The dose of alcohol available to the lactating infant was obtained by multiplying the alcohol intake of the mother by the proportion of breast milk in the infant's diet. We compared this dose with the Griffiths Scales of Mental Development, taking into account potentially confounding variables. RESULT: Three of the Griffiths scales increased slightly but significantly with increasing infant alcohol exposure; there was no association in the remaining 2 or average of the scales. DISCUSSION: We were unable to replicate the earlier deficit in motor skills associated with lactation alcohol use. One reason may be that the dose of alcohol reaching the lactating infant is small, and tests of infants and toddlers have limited ability to pick up small effects. Studies of older children may resolve the question of the safety of drinking while nursing.

Alcohol Drinking↗

Culture, stress and the parent-child relationship: a qualitative study of parents' perceptions of parenting.

UNLABELLED: This qualitative research project, based on the principles of grounded theory, has used a series of semi-structured interviews with parents to explore parental understanding of the culture in which today's children are growing up, the influences of that culture on their parenting and the potential impact on their child. METHODS: Sixteen mothers and one father whose children are participating in the Avon Longitudinal Study of Parents and Children were interviewed. The interviews covered various aspects of parenting and culture. Data from the transcribed interviews were analysed for emerging themes relating to parenting and areas where parenting can go wrong. These themes were developed further through an understanding of the literature on parenting and families. RESULTS: Analysis of the data suggested several key areas in which our culture imposes particular stresses on parents and, as such, does not support families or children. Prominent areas of stress were time pressures, particularly in the work-home arena, expectations of children to be active and achieving, financial pressures and the impact of consumerism on families. CONCLUSIONS: These data suggest that parents, although holding a very positive view of their children, do perceive parenting as being stressful. This is exacerbated by social structures and attitudes that do not value or support children and their families.

Adult↗

ALSPAC--the Avon Longitudinal Study of Parents and Children. I. Study methodology.

ALSPAC (The Avon Longitudinal Study of Parents and Children, formerly the Avon Longitudinal Study of Pregnancy and Childhood) was specifically designed to determine ways in which the individual's genotype combines with environmental pressures to influence health and development. To date, there are comprehensive data on approximately 10,000 children and their parents, from early pregnancy until the children are aged between 8 and 9. The study aims to continue to collect detailed data on the children as they go through puberty noting, in particular, changes in anthropometry, attitudes and behaviour, fitness and other cardiovascular risk factors, bone mineralisation, allergic symptoms and mental health. The study started early during pregnancy and collected very detailed data from the mother and her partner before the child was born. This not only provided accurate data on concurrent features, especially medication, symptoms, diet and lifestyle, attitudes and behaviour, social and environmental features, but was unbiased by parental knowledge of any problems that the child might develop. From the time of the child's birth many different aspects of the child's environment have been monitored and a wide range of phenotypic data collected. By virtue of being based in one geographic area, linkage to medical and educational records is relatively simple, and hands-on assessments of children and parents using local facilities has the advantage of high quality control. The comprehensiveness of the ALSPAC approach with a total population sample unselected by disease status, and the availability of parental genotypes, provides an adequate sample for statistical analysis and for avoiding spurious results. The study has an open policy in regard to collaboration within strict confidentiality rules.

Adult↗

Screening for amblyopia in preschool children: results of a population-based, randomised controlled trial. ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood.

INTRODUCTION: The rationale for preschool vision screening programmes has recently been questioned. Evidence about the effects of early treatment is needed, but it is not known how early the target conditions can reliably be detected. In this study, an intensive programme comprising several different screening methods, used at different ages up to 37 months, was compared with the usual practice of visual surveillance and ad hoc referrals. METHODS: Two groups were randomly selected from children in a population birth cohort study. The control group (n = 1461) received visual surveillance only. The intervention group (n = 2029) was offered in addition a programme of regular visual assessments by orthoptists testing visual acuity, ocular alignment, stereopsis and non-cycloplegic photorefraction. RESULTS: The intervention group programme yielded more children with amblyopia (1.6% vs. 0.5%, p < 0.01), and was more specific (95% vs. 92%, p < 0.01), than the control programme. The individual components of the intervention programme were compared. The cover test and visual acuity tests were poorly sensitive until the children were 37 months, but were always >99% specific. Photorefraction was more sensitive than acuity testing at all ages below 37 months, with specificity >95% at 31 and 37 months. CONCLUSIONS: Photorefraction would have detected more children less than 37 months of age with straight-eyed amblyopia than did visual acuity testing, but with more false positives. At 37 months, photorefraction plus a cover test would have been comparable in effectiveness to visual acuity testing plus a cover test.

Amblyopia↗

Should infants be screened for anaemia? A prospective study investigating the relation between haemoglobin at 8, 12, and 18 months and development at 18 months.

AIMS: To investigate the relation between haemoglobin in children followed longitudinally from 8 to 18 months, and developmental outcome at 18 months. METHODS: The Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC) is a longitudinal survey of a geographically defined population of children born in 1991-92. In a randomly selected subsample, blood samples were assayed for Hb at 8, 12, and 18 months; a developmental assessment was carried out at 18 months on 1141 children using the Griffiths Scales of Mental Development. RESULTS: There was a strong quadratic association between Hb at 8 months and performance on the locomotor subscale at 18 months. Average scores increased with increasing Hb up to 95 g/l; there was little additional developmental benefit in Hb levels beyond 95 g/l. Infants with Hb <95 g/l at 8 months of age scored on average 6 points lower on the locomotor subscale than infants with Hb >/= 95 g/l; infants with Hb <90 g/l at 8 months scored 12 points lower on the locomotor subscale than children with Hb >/= 90 g/l. CONCLUSIONS: Low Hb concentrations (</= 95 g/l) in 8 month old children are associated with impaired motor development at 18 months. This cut off point corresponds to the 5th centile of Hb at 8 months. The results indicate that if there is an adverse effect of low Hb on developmental outcome, screening may be more effective at 8 months or earlier, rather than after this age. We propose to examine the importance of infant anaemia in relation to more accurate and detailed long term outcomes as the children get older.

Analysis of Variance↗

Accidents and resulting injuries in premobile infants: data from the ALSPAC study.

BACKGROUND AND AIMS: Little is known about injuries resulting from accidents in premobile infants. We aimed to describe the pattern of minor accidents in infants and their resulting injuries. METHODS: The ALSPAC study collected data in successive postal questionnaires. At 6 months of age, parents were asked to describe any accident since birth. The type of fall, distance fallen, resulting injury, and help sought were independently coded. Burns were similarly coded. RESULTS: A total of 11 466 responses were available. In 2554 children, 3357 falls were reported; 53% fell from beds or settees and 12% fell from arms or while being carried. Only 14% reported visible injury, of which 56% were bruises; 97% of injuries specified involved the head. Only 21 falls (<1%) resulted in concussion or fracture. A burn or scald occurred in 172 cases (1.5%). The main causes of scalds were hot drinks and water, with contact burns caused by radiators, cookers, and hot food. CONCLUSIONS: Falls in young infants are common while burns are rare. Injuries from falls are infrequent, predominantly trivial, and almost entirely confined to the head. Falls from beds and settees did not result in skull fractures. Serious injury was the result of complex accidents.

Accidental Falls↗

Premature adiposity rebound in children treated for acute lymphoblastic leukemia.

The adiposity rebound (AR), when body mass index begins to increase after its nadir in childhood, is a critical period for the regulation of energy balance and adult obesity risk. The aim of the present study was to test whether children treated for acute lymphoblastic leukemia (ALL) experience premature AR. This might, in part, explain their tendency to develop obesity. Timing of AR was assessed by visual inspection of body mass index plots in 68 patients treated for ALL in first remission. This sample comprised all eligible patients treated in Scotland between 1991 and 1998, age 30 months or less at the time of diagnosis. Timing of AR in patients was compared against a cohort of 889 healthy British children studied during the 1990s using the same method. AR occurred significantly earlier in the patients treated for ALL (chi(2) test, P < 0.001). The AR had occurred in 43% (29 of 68) of the patients and 4% (40 of 889) of the comparison group by age 37 months. At 49 months AR had occurred in 81% (55 of 68) of the patients and 21% (190 of 889) of the comparison group. Treatment of ALL is associated with a significantly advanced AR. This might, in part, explain the extremely high prevalence of obesity in long-term survivors. Clinical management should focus on minimizing excess weight gain during therapy to reduce long-term obesity risk.

Adipose Tissue↗

Fat content of the diet among preschool children in southwest Britain: II. relationship with growth, blood lipids, and iron status.

OBJECTIVE: In most countries, it is recommended that adults restrict fat intake to 30% to 35% of energy to reduce the risk of coronary heart disease and certain cancers. However, the appropriate level of fat in the diet of children is hotly debated. It has been generally accepted that fat intake by children under 2 years of age should not be limited because of fears that nutrient intakes and thus growth and iron status might be compromised. However, there is very little longitudinal information on the relationship between fat intake and growth in representative populations of free-living children under 2 years old. The objective of this study was to investigate the relationship between fat intake as a percentage of energy, and nutrient adequacy, growth, blood lipids, and iron status in 18- and 43-month-old children. DESIGN: This study forms part of the Avon Longitudinal Study of Parents and Children (ALSPAC)-a geographically-based cohort study in southwest England. A randomly selected subsample of the ALSPAC cohort attended research clinics approximately every 6 months from birth, at which a variety of anthropometric and other measurements were made. Dietary intakes at 18 and 43 months were assessed using a 3-day unweighed food record. A capillary blood sample was taken at 18 months for measurement of hemoglobin and ferritin levels. Nonfasting venous blood samples were taken at 31 and 43 months and analyzed for total and high-density lipoprotein cholesterol. The children were divided into quartiles of fat intake as a percentage of energy (QFI). QFI groups were compared for the number of children reaching recommended nutrient intakes, and for anthropometry, measures of iron status, and blood lipid levels. PARTICIPANTS: Nine hundred fifty-one children at 18 months and 805 children at 43 months. RESULTS: The mean (standard deviation) percentages of energy from fat in each quartile at 18 months were 31.2 (2.8), 36.1 (0.9), 39.1 (0.8), and 43.1 (2.2), corresponding to a fat intake in grams of 37.3 (8.1), 44.3 (8.1), 50.4 (10.2), and 55.4 (12.7). The number of children failing to reach recommended intake levels for zinc and vitamin A fell with increasing fat intake, while the number of children consuming less than the recommendations for iron and vitamin C rose at both ages. Despite this, there was no association between fat intake at 18 months and mean height or body mass index (BMI) at either 18 or 31 months. Fat intake at 43 months was also unassociated with concurrent or subsequent height or BMI. There was also no significant increase in the number of children falling below the tenth percentile for height or BMI as QFI fell. Mean ferritin levels at 18 months fell in both sexes as QFI increased. Total cholesterol levels at 31 months were significantly associated with QFI at 18 months, and rose from 3.99 mmol/l in the lowest QFI in boys, to 4.31 mmol/l in the highest QFI. QFI at 43 months was unassociated with cholesterol levels. CONCLUSIONS: These data do not suggest that fat intakes are an important determinant of growth in these children, even before the age of 2 years, or that children at the bottom of the range of fat intakes are experiencing delayed growth. On the other hand, there is also no evidence in this study that children on higher fat intakes are at a greater risk of becoming obese. In contrast to a number of US studies, we have not found children on lower fat intakes to have lower iron intakes-indeed higher fat intakes were associated with a greater chance of consuming less than the recommended intake of iron and with lower ferritin levels. The association of higher fat intakes with higher total cholesterol levels among boys is of concern, as there is evidence that the process of atherosclerosis begins during the preschool years.

Age Distribution↗

The role of brothers and sisters in the gender development of preschool children.

The study examined whether the sex of older siblings influences the gender role development of younger brothers and sisters of age 3 years. Data on the Pre-School Activities Inventory, a measure of gender role behavior that discriminates within as well as between the sexes, were obtained in a general population study for 527 girls and 582 boys with an older sister, 500 girls and 561 boys with an older brother, and 1665 singleton girls and 1707 singleton boys. It was found that boys with older brothers and girls with older sisters were more sex-typed than same-sex singletons who, in turn, were more sex-typed than children with other-sex siblings. Having an older brother was associated with more masculine and less feminine behavior in both boys and girls, whereas boys with older sisters were more feminine but not less masculine and girls with older sisters were less masculine but not more feminine.

Birth Order↗