Biomedical subjects

John B Carlin

Publications and source records attributed to John B Carlin.

At least 19 recordsLinked to original sources

PubMed2007

A simulation study of odds ratio estimation for binary outcomes from cluster randomized trials.

We used simulation to compare accuracy of estimation and confidence interval coverage of several methods for analysing binary outcomes from cluster randomized trials. The following methods were used to estimate the population-averaged intervention effect on the log-odds scale: marginal logistic regression models using generalized estimating equations with information sandwich estimates of standard error (GEE); unweighted cluster-level mean difference (CL/U); weighted cluster-level mean difference (CL/W) and cluster-level random effects linear regression (CL/RE). Methods were compared across trials simulated with different numbers of clusters per trial arm, numbers of subjects per cluster, intraclass correlation coefficients (rho), and intervention versus control arm proportions. Two thousand data sets were generated for each combination of design parameter values. The results showed that the GEE method has generally acceptable properties, including close to nominal levels of confidence interval coverage, when a simple adjustment is made for data with relatively few clusters. CL/U and CL/W have good properties for trials where the number of subjects per cluster is sufficiently large and rho is sufficiently small. CL/RE also has good properties in this situation provided a t-distribution multiplier is used for confidence interval calculation in studies with small numbers of clusters. For studies where the number of subjects per cluster is small and rho is large all cluster-level methods may perform poorly for studies with between 10 and 50 clusters per trial arm.

Algorithms↗

PubMed2006

Clinical features and outcomes of childhood dilated cardiomyopathy: results from a national population-based study.

BACKGROUND: Despite considerable mortality, population-based prognostic factors for childhood dilated cardiomyopathy are lacking. METHODS AND RESULTS: A population-based cohort study was undertaken of all children in Australia who presented with cardiomyopathy at age 0 to 10 years between January 1, 1987, and December 31, 1996. A single cardiologist analyzed all cardiac investigations, and a single pathologist analyzed histopathological material. There were 184 subjects with dilated cardiomyopathy. Positive viral identification or lymphocytic myocarditis was found in 30 (68.2%) of 44 cases with available early histology and 8 of 9 cases presenting with sudden death. Freedom from death or transplantation was 72% (95% CI, 65% to 78%) 1 year after presentation and 63% (95% CI, 55% to 70%) at 5 years. By proportional hazards regression analysis, risk factors for death or transplantation comprised age >5 years at presentation (hazard ratio 5.6, 95% CI, 2.6 to 12.0), familial dilated cardiomyopathy (hazard ratio, 2.9; 95% CI, 1.5 to 5.6), lower initial fractional shortening z score (hazard ratio per z-score unit, 0.75; 95% CI, 0.65 to 0.87), and failure to increase fractional shortening z score during follow-up (hazard ratio per unit increase, 0.68; 95% CI, 0.58 to 0.79). At follow-up, 78 (44.6%) of 175 cases diagnosed during life have no symptoms and are not taking any cardiac medication. CONCLUSIONS: Early mortality is high in childhood dilated cardiomyopathy, but the clinical status of long-term survivors is good. This population-based study identifies children at risk of adverse events.

Cardiomyopathy, Dilated↗

PubMed2006

Is childhood immunisation associated with atopic disease from age 7 to 32 years?

BACKGROUND: There is ongoing conjecture over whether childhood immunisation leads to an increased risk of developing atopic diseases. OBJECTIVE: To examine associations between childhood immunisation and the risk of atopic disease. METHOD: Immunisation histories of 8443 Tasmanian children born in 1961 obtained from school medical records were linked to the Tasmanian Asthma Study. Associations between immunisation status and atopic diseases were examined while adjusting for possible confounders using multiple logistic regression. RESULTS: Diphtheria immunisation was weakly associated with an increased risk of asthma by age 7 years (odds ratio (OR) 1.3, 95% confidence interval (CI) 1.1 to 1.7), but there was no evidence of any association for four other vaccinations studied. An increased risk of eczema by age 7 years was associated with immunisation against diphtheria (OR 1.5, 95% CI 1.1 to 2.1), tetanus (OR 1.5, 95% CI, 1.1 to 2.0), pertussis (OR 1.5, 95% CI 1.1 to 1.9) and polio (OR 1.4, 95% CI 1.0 to 1.9) but not small pox. Similar but slightly weaker patterns of association were observed between the risk of food allergies and immunisation against diphtheria (OR 1.5, 95% CI 1.0 to 2.1), pertussis (OR 1.4, 95% CI 1.1 to 1.9), polio (OR 1.4, 95% CI 1.00 to 2.1) and tetanus (OR 1.30 95% CI 0.99 to 1.70), but not with small pox. There was no evidence of associations between immunisation history and hay fever, or incidence of later-onset atopic outcomes. CONCLUSIONS: The few effects seen in this study are small and age-dependent, and nearly all our findings support numerous previous studies of no effect of vaccines on asthma. Based on these findings, the fear of their child developing atopic disease should not deter parents from immunising their children, especially when weighed against the benefits.

Adolescent↗

PubMed2006

Perinatal risk factors altering regional brain structure in the preterm infant.

Neuroanatomical structure appears to be altered in preterm infants, but there has been little insight into the major perinatal risk factors associated with regional cerebral structural alterations. MR images were taken to quantitatively compare regional brain tissue volumes between term and preterm infants and to investigate associations between perinatal risk factors and regional neuroanatomical alterations in a large cohort of preterm infants. In a large prospective longitudinal cohort study of 202 preterm and 36 term infants, MR scans at term equivalent were undertaken for volumetric estimates of cortical and deep nuclear grey matter, unmyelinated and myelinated white matter (WM) and CSF within 8 parcellated regions for each hemisphere of the brain. Perinatal correlates analysed in relation to regional brain structure included gender, gestational age, intrauterine growth restriction, bronchopulmonary dysplasia, white matter injury (WMI) and intraventricular haemorrhage. Results revealed region-specific reductions in brain volumes in preterm infants compared with term controls in the parieto-occipital (preterm mean difference: -8.1%; 95% CI = -13.8--2.3%), sensorimotor (-11.6%; -18.2--5.0%), orbitofrontal (-30.6%; -49.8--11.3%) and premotor (-7.6%; -14.2--0.9%) regions. Within the sensorimotor and orbitofrontal regions cortical grey matter and unmyelinated WM were most clearly reduced in preterm infants, whereas deep nuclear grey matter was reduced mainly within the parieto-occipital and subgenual regions. CSF (ventricular and extracerebral) was doubled in volume within the superior regions in preterm infants compared with term controls. Cerebral WMI and intrauterine growth restriction were both associated with a more posterior reduction in brain volumes, whereas bronchopulmonary dysplasia was associated with a more global reduction across all regions. In contrast degree of immaturity was not related to regional brain structure among preterm infants. In summary, preterm birth is associated with regional cerebral tissue reductions, with the adverse pattern varying between risk factors. These findings add to our understanding of the potential pathways leading to altered brain structure and outcome in the preterm infant.

Brain↗

PubMed2006

Promoting social inclusion in schools: a group-randomized trial of effects on student health risk behavior and well-being.

OBJECTIVES: We sought to test the efficacy of an intervention that was designed to promote social inclusion and commitment to education, in reducing among students health risk behaviors and improving emotional well-being. METHODS: The design was a cluster-randomized trial in 25 secondary schools in Victoria, Australia. The subjects were 8th-grade students (aged 13 to 14 y) in 1997 (n=2545) and subsequent 8th-grade students in 1999 (n=2586) and 2001 (n=2463). The main outcomes were recent substance use, antisocial behavior, initiation of sexual intercourse, and depressive symptoms. RESULTS: At 4-year follow-up, the prevalence of marked health risk behaviors was approximately 20% in schools in the comparison group and 15% in schools in the intervention group, an overall reduction of 25%. In ordinal logistic regression models a protective effect of intervention was found for a composite measure of health risk behaviors in unadjusted models (odds ratio [OR]= 0.69; 95% confidence interval [CI]= 0.50, 0.95) and adjusted models (OR= 0.71; CI =0.52, 0.97) for potential confounders. There was no evidence of a reduction in depressive symptoms. CONCLUSION: The study provides support for prevention strategies in schools that move beyond health education to promoting positive social environments.

Adolescent↗

PubMed2006

Reduction in cerebellar volumes in preterm infants: relationship to white matter injury and neurodevelopment at two years of age.

A substantial number of prematurely born infants will experience later neurodevelopmental challenges. Abnormal development of the cerebellum may be related to some of the impairments exhibited by preterm children. To test the hypothesis that cerebellar development is structurally impaired in preterm infants and associated with adverse outcomes, we studied 83 preterm infants and 13 term controls using volumetric magnetic resonance imaging techniques to obtain cerebellar volumes (CV) at term corrected and subsequent neurodevelopmental assessment at 2 y of age. The preterm group had smaller mean CV at term compared with the term control infants [mean (SD) CV, 22.0 (5.0) versus 23.5 (5.0) cc; mean difference (95% confidence interval), 1.5 (-1.5, 4.4)] although this did not reach statistical significance. Within the preterm group, there was evidence of a reduction in CV related to the presence of white matter injury (WMI) after adjusting for intracranial volume (ICV) [WMI grade 1 versus grade 2: mean (SD) CV, 23.6 (5.0) versus 21.6 (4.5); p = 0.01; WMI grade 1 versus grade 3 and 4: 23.6 (5.0) versus 20.8 (5.6); p = 0.07]. Within the preterm infants, there was no apparent relationship between CV at term and gestational age at birth after adjusting for ICV. At 2 y of age, CV showed a weak correlation with cognitive and motor development, although this was principally mediated by WMI. In conclusion, we found no evidence for a primary impairment in cerebellar development in relation to prematurity, although there was evidence for a secondary effect of cerebral WMI on cerebellar development independent of immaturity.

Aging↗

PubMed2006

Evaluation of a decision aid for prenatal testing of fetal abnormalities: a cluster randomised trial [ISRCTN22532458].

BACKGROUND: By providing information on the relative merits and potential harms of the options available and a framework to clarify preferences, decision aids can improve knowledge and realistic expectations and decrease decisional conflict in individuals facing decisions between alternative forms of action. Decision-making about prenatal testing for fetal abnormalities is often confusing and difficult for women and the effectiveness of decision aids in this field has not been established. This study aims to test whether a decision aid for prenatal testing of fetal abnormalities, when compared to a pamphlet, improves women's informed decision-making and decreases decisional conflict. METHODS/DESIGN: A cluster designed randomised controlled trial is being conducted in Victoria, Australia. Fifty General Practitioners (GPs) have been randomised to one of two arms: providing women with either a decision aid or a pamphlet. The two primary outcomes will be measured by comparing the difference in percentages of women identified as making an informed choice and the difference in mean decisional conflict scores between the two groups. Data will be collected from women using questionnaires at 14 weeks and 24 weeks gestation. The sample size of 159 women in both arms of the trial has been calculated to detect a difference of 18% (50 to 68%) in informed choice between the two groups. The required numbers have been adjusted to accommodate the cluster design, miscarriage and participant lost--to--follow up. Baseline characteristics of women will be summarised for both arms of the trial. Similarly, characteristics of GPs will be compared between arms. Differences in the primary outcomes will be analysed using 'intention-to-treat' principles. Appropriate regression techniques will adjust for the effects of clustering and include covariates to adjust for the stratifying variable and major potential confounding factors. DISCUSSION: The findings from this trial will make a significant contribution to improving women's experience of prenatal testing and will have application to a variety of maternity care settings. The evaluation of a tailored decision aid will also have implications for pregnancy care providers by identifying whether or not such a resource will support their role in providing prenatal testing information.

Cluster Analysis↗

PubMed2006

Birthweight and coronary heart disease in a cohort born 1857-1900 in Melbourne, Australia.

BACKGROUND: The widely observed association between birth size and risk of later coronary heart disease (CHD) has not been examined in an impoverished pre-20th century birth cohort. METHODS: Birth weights and maternal characteristics, for births between 1857 and 1900 in a charity hospital, were recorded from preserved ledgers. Names were linked to death certificates to determine age and cause of death. Death with CHD was coded using specific criteria, and survival analysis methods were used to relate risk of CHD to birth weight, allowing for competing causes of death and adjusting for potentially confounding maternal factors. RESULTS: Death certificates were traced for 8,584 (53%) of 16,272 registered live-births. Survival analyses were confined to 2,938 subjects (1,572 male, 1,366 female) who survived beyond age 40, since none of the 486 CHD cases was recorded earlier. CHD risk increased with time, but there was no evidence that it was related to birth weight, in men or women. CONCLUSIONS: We did not replicate findings in more recent cohorts. This may represent a true lack of association in a historical cohort who we believe remained impoverished through their early life. However, we acknowledge the strong possibility of misclassification of cause of death by the person filling in the death certificate and/or our coding criteria, and temporal change in diagnostic criteria for CHD. We cannot exclude the possibility that low birth weight babies 'programmed' in utero for later CHD were more likely to die in infancy, in this cohort with a high infant mortality rate.

Aged↗

PubMed2006

Atopic disease and breast-feeding--cause or consequence?

BACKGROUND: A number of studies have observed an association between breast-feeding and increased risk of development of asthma and eczema. It has been proposed that these results might be due to early signs of atopic disease in the infant causing mothers to prolong breast-feeding. OBJECTIVE: We sought to determine whether early symptoms of atopic disease (eczema, food reaction, or asthma) or positive skin prick test responses reduce the likelihood of ceasing breast-feeding. METHODS: A prospective birth cohort of 620 infants from Melbourne, Australia, was used. Telephone interviews every 4 weeks were conducted until 64 weeks and then again at 78 and 104 weeks to determine duration of breast-feeding (both exclusive and total) and evidence of atopic disease. Because of the varying time of onset of atopic symptoms, they were modeled as time-varying covariates in Cox models. RESULTS: Only 52 (8.4%) infants did not establish breast-feeding, whereas an additional 103 (25.0%) did not establish exclusive breast-feeding. Early signs of atopic disease or sensitization were independently associated with an approximately 28% reduction in risk of ceasing exclusive breast-feeding (adjusted hazard ratio, 0.72; 95% CI, 0.53-0.97); P=.029), but there was no evidence for a relationship with risk of ceasing breast-feeding completely (adjusted hazard ratio, 1.12; 95% CI, 0.92-1.37; P=.262). CONCLUSION: Early signs of atopic disease might prolong the duration of exclusive breast-feeding. This could mask a protective effect of breast-feeding or even result in breast-feeding appearing to be a risk factor for the development of atopic diseases. Future investigation of the relationship between breast-feeding and atopic diseases should consider this possibility.

Adult↗

PubMed2006

Teen smokers reach their mid twenties.

PURPOSE: Most outcome studies of adolescent smokers have focused on tobacco use in the short term. Few have reported on the health of adolescent smokers as they reach young adulthood. METHODS: The design was a 10-year, eight-wave cohort study of a state-wide community sample of 1943 participants in Victoria, Australia. Participants were initially aged 14 to 15 years. Tobacco use was assessed with self-reported frequency of use and a seven-day retrospective diary. The Fagerstrom Test for Nicotine Dependence was used to define nicotine dependence in young adulthood. A computerized interview assessment was used during the teens and in young adulthood. RESULTS: Former daily smokers in adolescence accounted for most cases of nicotine dependence and high-dose (10+ cigarettes per day) smoking in young adulthood. Other substance abuse and psychiatric morbidity in young adulthood were also markedly elevated in this group. This was most clearly evident for cannabis dependence, where close to two-thirds of all cases were formerly daily tobacco smokers. Male smokers were more likely to continue as young adults. Persistent symptoms of depression and anxiety during the teens predicted progression to nicotine dependence, as did having a parent smoking daily. CONCLUSIONS: The poor health outcomes of daily adolescent smokers as they reach young adulthood provide a rationale for greater tobacco control initiatives directed at early users. Clinical interventions might usefully consider factors such as psychiatric morbidity and parental smoking.

Adolescent↗

PubMed2006

Risk factors for intussusception in infants in Vietnam and Australia: adenovirus implicated, but not rotavirus.

OBJECTIVE: This study aimed to investigate risk factors for the development of intussusception in infants in a developing country with a suspected high incidence and in a developed country with a low incidence. STUDY DESIGN: A prospective case-control study of infants <2 years of age with idiopathic intussusception confirmed by air enema or surgery was conducted at the National Hospital of Paediatrics (NHP), Vietnam (n = 533) and the Royal Children's Hospital (RCH), Australia (n = 51). Diagnosis was validated in a subset (84% NHP; 67% RCH) by an independent blinded radiologist. Risk factor assessment was performed using a standardized questionnaire. Stool specimens were assayed for bacterial, viral, and parasitic agents. RESULTS: The incidence of intussusception in Vietnam was 302/100,000 in infants <1 year of age (95% CI: 258-352), substantially higher than in Australia (71/100,000). A strong association with adenovirus infection was observed at both sites (cases positive at NHP: 34%, OR 8.2; cases positive at RCH: 40%, OR 44). No association was identified between intussusception and rotavirus, other enteric pathogens, oral polio vaccine, feeding practices, or living conditions. CONCLUSIONS: The incidence of intussusception in infants was markedly higher in Vietnam than in Australia. A strong association between adenovirus infection and intussusception was identified at both sites suggesting that adenovirus may play a role in the etiology of intussusception.

Adenovirus Infections, Human↗

PubMed2006

Interobserver variability of the 5-minute Apgar score.

OBJECTIVES: To assess interobserver variability of Apgar scores assigned with video recordings of neonatal resuscitation (AS(video)) and compare the scores assigned by observers of videos to the Apgar score given by staff attending the delivery (AS(del)). STUDY DESIGN: Ten-second clips of 30 newborns taken at 5 minutes were shown to observers. Infants were 23 to 40 weeks' gestation, received varying degrees of resuscitation, and were monitored with pulse oximetry. Forty-two observers (neonatal/obstetric medical/nursing staff) scored infants' respiratory effort, muscle tone, reflex irritability, and color. The value for heart rate was assigned from the oximeter, which was masked in all clips. All 42 AS(video) and the AS(del) were represented graphically for each infant. Interobserver reliability was assessed by use of a variance components model. RESULTS: AS(video) varied widely between observers. Variability was large for all 4 elements of the score observers assigned and was seen irrespective of the infant's level of illness. AS(del) was greater than AS(video) in most cases, on average by 2.4 points. There was no evidence that the level of discrepancy was substantially different between groupings of staff. CONCLUSION: The Apgar score has poor interobserver reliability. More objective and precise measures of newborns' condition are required.

Apgar Score↗

PubMed2006

Financial stress, smoking cessation and relapse: results from a prospective study of an Australian national sample.

AIMS: Our aim was to examine the association between financial stress and subsequent smoking cessation among smokers, and relapse among ex-smokers. DESIGN AND PARTICIPANTS: Data came from the first two waves of the Household Income and Labour Dynamics in Australia (HILDA) survey. The size of the subsample of smokers was 2076, and that of ex-smokers was 2717. Data collection was based on face-to-face interviews. MEASUREMENT: Eight questionnaire items (e.g. difficulty paying electricity, gas or telephone bills and going without meals due to shortage of money) were used to construct a nine-point financial stress index. FINDINGS: Smokers with more financial stress were less likely to quit, with the odds of quitting reducing by 13% (95% CI: 4-21%; P = 0.008) per unit of the financial stress index. Ex-smokers with more financial stress were more likely to relapse (P < 0.001). CONCLUSIONS: Special programmes may have to be implemented to counter the potentially adverse effects of tobacco price increases on smokers who have financial stress and fail to quit smoking.

Adolescent↗

PubMed2006

The burden of rotavirus-related illness among young children on the Australian health care system.

OBJECTIVE: To provide estimates of the annual number and cost of hospital admissions, emergency department (ED) visits and general practitioner (GP) visits for rotavirus (RV) related acute gastroenteritis (AGE) in young children in Australia. METHODS: Numbers of hospitalisations for AGE were determined from national hospital morbidity data from July 1998 to June 2003. The fraction of these hospitalisations that may be attributed to RV was estimated by direct linkage of hospital admissions and pathology data from hospitals in two regions of Australia and by a second indirect method using the seasonal variation of RV infection. Numbers of ED visits were estimated using statewide data from Victoria and New South Wales (NSW), and numbers of GP visits were estimated from representative sample data for GP visits. Costs of RV hospital admissions and ED visits were estimated from national hospital cost data. RESULTS: RV continues to account for around 10,000 hospitalisations annually for children aged less than five in Australia at an average cost of 1890 dollars each. There are an additional 22,000 ED visits a year where the child is not subsequently hospitalised, each at a cost of 320 dollars, and approximately 115,000 visits to GPs by children in this age group for RV-AGE at a cost of 36.60 dollars each. CONCLUSIONS: The annual cost of hospital admissions, ED visits and GP visits associated with RV infection in young children in Australia is approximately 30 million dollars. IMPLICATIONS: Vaccination against RV disease in Australia may provide substantial savings to the health care system, depending on the cost and effectiveness of an immunisation program.

Australia↗

PubMed2006

Women's and health professionals' preferences for prenatal testing for Down syndrome in Australia.

AIM: To describe and compare women's and health professionals' preferences for prenatal screening tests for Down syndrome. DESIGN: Cross-sectional questionnaire survey. PARTICIPANTS AND SETTING: Women (n = 322) attending for a glucose challenge test at 26 weeks gestation and health professionals (266 midwives and 34 obstetricians) at the Royal Women's Hospital, Melbourne, between 13 December 2002 and 30 April 2003. OUTCOME MEASURES: The relative value participants attach to attributes of Down syndrome screening tests as determined by conjoint analysis and ranking scales. RESULTS: Women and health professionals shared similar relative values regarding the importance of detection rate of screening tests, according to coefficients from conjoint analysis models. However, health professionals placed higher relative values on timing of prenatal tests and risk associated with the subsequent diagnostic test than did women. Comparison of coefficients suggests that, compared with health professionals, women would wait longer and accept a greater decrease in detection rate for a test if it was safer. Using the more traditional ranking scale, the safest test was ranked first by 56% of women while 47% of health professionals ranked a test with the highest detection rate first. Equal proportions ( approximately 10%) in both groups ranked the earliest test first. CONCLUSION: There is a general agreement between pregnant women and health professionals regarding the relative importance they attach to different attributes of a test. However, health professionals appeared to favour earlier timing of tests while women placed greater emphasis on safety. Utilising two different measures of preference demonstrated the complexity of decision-making.

Adolescent↗

PubMed2006

Using bivariate models to understand between- and within-cluster regression coefficients, with application to twin data.

In the regression analysis of clustered data it is important to allow for the possibility of distinct between- and within-cluster exposure effects on the outcome measure, represented, respectively, by regression coefficients for the cluster mean and the deviation of the individual-level exposure value from this mean. In twin data, the within-pair regression effect represents association conditional on exposures shared within pairs, including any common genetic or environmental influences on the outcome measure. It has therefore been proposed that a comparison of the within-pair regression effects between monozygous (MZ) and dizygous (DZ) twins can be used to examine whether the association between exposure and outcome has a genetic origin. We address this issue by proposing a bivariate model for exposure and outcome measurements in twin-pair data. The between- and within-pair regression coefficients are shown to be weighted averages of ratios of the exposure and outcome variances and covariances, from which it is straightforward to determine the conditions under which the within-pair regression effect in MZ pairs will be different from that in DZ pairs. In particular, we show that a correlation structure in twin pairs for exposure and outcome that appears to be due to genetic factors will not necessarily be reflected in distinct MZ and DZ values for the within-pair regression coefficients. We illustrate these results in a study of female twin pairs from Australia and North America relating mammographic breast density to weight and body mass index.

Australia↗

PubMed2006

Personality and substance use disorders in young adults.

BACKGROUND: There have been no studies of the co-occurrence of personality and substance use disorders in young community-dwelling adults. AIMS: To examine the association between DSM-IV personality disorders and substance use disorders in a large representative sample of young community-dwelling participants. METHOD: Young Australian adults (n=1520, mean age=24.1 years) were interviewed to determine the prevalence of substance use disorders; 1145 also had an assessment for personality disorder. RESULTS: The prevalence of personality disorder was 18.6% (95% CI 16.5-20.7). Personality disorder was associated with indices of social disadvantage and the likely presence of common mental disorders. Independent associations were found between cluster B personality disorders and substance use disorders. There was little evidence for strong confounding or mediating effects of these associations. CONCLUSIONS: In young adults, there are independent associations between cluster B personality disorders and substance use disorders.

Adolescent↗

PubMed2006

Maternal dietary intake in twin pregnancies: does it diminish towards term?

We tested the hypothesis that energy intake among women with twin pregnancies decreases in late gestation, as the uterus enlarges and they become increasingly uncomfortable. We asked women to recall dietary intake for the previous 24 hours, every 2 weeks from around 29 weeks of gestation, using a photographic atlas and other strategies to estimate portion size. Eighty women provided data at around 29, 31, 33 and 35 weeks of gestation. We calculated total energy intake, and energy intake from carbohydrate, fat and protein. Data were log transformed to reduce skewness. Using mixed effects linear regression models, we found minimal evidence that total energy intake changed over this time period, either before or after adjustment for potential confounding factors (95% confidence interval for relative change per week: -1.4%, 0.6%). There was weak evidence of a small decline in carbohydrate intake over time, both before and after controlling for energy intake. We cannot exclude change in energy intake or diet composition before 29 weeks or after 35 weeks of twin gestation.

Diet↗