Proportion Of Optimal Birth Weight Research Articles

The longitudinal effects of neonatal anthropometry on attention problems in males and females

AbstractBackgroundThe longitudinal impact of fetal growth on attention problems in males and females is unclear. This study aims to evaluate the impact of fetal growth assessed by neonatal anthropometry throughout childhood and adolescence in males and females separately.MethodsWe compared neonatal anthropometry (birth weight (BW), head circumference (HC), proportion of optimal birthweight (POBW)) and asymmetry (head‐to‐abdominal circumference ratio (HC/AC) and ponderal index (PI)) at birth with parental assessment of the child behavior checklist attention‐problem syndrome (CBCL‐AP) raw score measured at ages five, eight, 10, 14 and 17. We used univariable and multivariable linear mixed‐effects modeling. Sensitivity analyses included excluding pre‐term births, teacher ratings and treating the CBCL‐AP as an ordinal variable.ResultsIn males, a 1‐SD lower BW, increased CBCL‐AP by 0.234 (95%CI [−0.422, −0.0497]). In males, a 1‐SD lower HC increased CBCL‐AP by 0.316 (95%CI [0.495, 0.133]). In males, there was a U‐shaped relationship between HC/AC and CBCL‐AP throughout childhood and adolescence; a curvilinear relationship was observed between POBW and CBCL‐AP. In females, a 1 SD lower HC increased CBCL‐AP 0.424 (95%CI [0.726, 0.133]), but every increased year of age reduced the effect by 0.027 (95% CI: 0.006–0.05). In females, there was no clear relationship between BW, POBW or HC/AC and CBCL‐AP. In males and females, PI was not significantly associated with CBCL‐AP. The exclusion of pre‐term births and analysis of teacher‐rated attention problems was consistent with the primary results.ConclusionsUsing a longitudinal design, our study suggests a male vulnerability to attention problems throughout childhood and adolescence from neonatal anthropometry. The relationships in females appear to be limited to childhood.

Prenatal exposure to mixtures of persistent environmental chemicals and fetal growth outcomes in Western Australia

Background: Environmental chemicals have been implicated in the etiology of impaired fetal growth; however, few studies have assessed the effects of chemical mixtures or considered the possibility of non-monotonic exposure–response relationships for chemicals that act through the endocrine system. Methods: We assessed exposure to polybrominated diphenyl ethers, organochlorine pesticides, metals, and perfluoroalkyl substances in blood and urine samples collected two weeks prior to delivery in 166 non-smoking pregnant women, and subsequent birth weight, length, and head circumference of neonates who were part of the Australian Maternal Exposures to Toxic Substances (AMETS) study. We used Bayesian structured additive regression models with spike–slab priors to estimate mixture effects, identify important exposures, and model non-linearity in exposure–response relationships. Results: An increase in cesium exposure measured in whole blood from the 10th to 90th percentile was associated with a reduction in both birth weight (-236.5 g, 90% credible interval: -458.1 to -6.5 g) and the proportion of optimal birth weight (-8.6%, 90% credible interval: -14.8 to -0.4%), after adjusting for potential confounders. We identified several other chemicals and mixtures that may be associated with fetal growth, some non-linearly; however, 90% credible intervals contained the null. Conclusions: Using a Bayesian penalised regression method that is robust to multicollinearity, we assessed the shapes of exposure–response relationships, controlled for confounding by co-exposure, and estimated the single and combined effects of a large mixture of correlated environmental chemicals on fetal growth. While exposure concentrations in the AMETS study were generally low, our findings suggest that cesium exposure is associated with a reduction in birth weight. The potential for non-monotonic relationships between environmental chemicals and fetal growth outcomes warrants further study.

Associations between biological and sociodemographic risks for developmental vulnerability in twins at age 5: a population data linkage study in Western Australia

ObjectiveTo investigate the prevalence of, and associations between, prenatal and perinatal risk factors and developmental vulnerability in twins at age 5.DesignRetrospective cohort study using bivariate and multivariable logistic regression.SettingWestern Australia...

Are preterm birth and intra-uterine growth restriction more common in Western Australian children of immigrant backgrounds? A population based data linkage study

BackgroundTo compare the prevalence of preterm birth, post term birth, intra-uterine growth restriction and distribution of Apgar scores in offspring of foreign-born women in Western Australia with that of their Australian-born non-Indigenous and Indigenous counterparts.MethodsA population-based linked data study, involving 767,623 singleton births in Western Australia between 1980 and 2010 was undertaken. Neonatal outcomes included preterm birth, post term births, intra-uterine growth restriction (assessed using the proportion of optimal birth weight) and low Apgar scores. These were compared amongst foreign-born women from low, lower-middle, upper middle and high income countries and Australian-born non-Indigenous and Indigenous women over two different time periods using multinomial logistic regression adjusted for covariates.ResultsCompared with Australian born non-Indigenous women, foreign-born women from low income countries were at some increased risk of extreme preterm (aRRR 1.59, 95% CI 0.87, 2.89) and very early preterm (aRRR 1.63, 95% CI 0.92, 2.89) births during the period from 1980 to 1996. During the period from 1997 to 2010 they were also at some risk of extreme preterm (aRRR 1.42, 95% CI 0.98, 2.04) very early preterm (aRRR 1.34, 95% CI 1.11, 1.62) and post term birth (aRRR 1.93, 95% CI 0.99, 3.78). During this second time period, other adverse outcomes for children of foreign-born women from low income and middle income countries included increases in severe (aRRR 1.69, 95% CI 1.30, 2.20; aRRR 1.72, 95% CI 1.53, 1.93), moderate (aRRR 1.54, 95% CI 1.32, 1.81; aRRR 1.59, 95% CI 1.48, 1.70) and mild (aRRR 1.28, 95% CI 1.14, 1.43; aRRR 1.31, 95% CI 1.25, 1.38) IUGR compared to children of Australian-born non-Indigenous mothers. Uniformly higher risks of adverse outcomes were also demonstrated for infants of Indigenous mothers.ConclusionsOur findings illustrate the vulnerabilities of children born to foreign women from low and middle-income countries. The need for exploratory research examining mechanisms contributing to poorer birth outcomes following resettlement in a developed nation is highlighted. There is also a need to develop targeted interventions to improve outcomes for these women and their families.

Sex specific influence on the relationship between maternal exposures to persistent chemicals and birth outcomes.

Prenatal exposure to persistent pollutants has been associated with adverse birth outcomes, although few studies have investigated the influence of the sex of the infant. Sex specific differences have been associated with neurobehavioural impacts from environmental exposures with limited and contrary findings in relation to persistent pollutants. This study investigated the relationships between maternal exposure to a range of metals, polychlorinated biphenyls and pesticides measured in biological samples and birth outcomes with a specific focus on the sex of the infant. Outcome measures used included birth weight, birth length and head circumference, proportion of optimal birth weight (POBW), proportion of optimal birth length, proportion of optimal head circumference (POHC) and ponderal index. In general maternal urinary and blood metals, plasma polychlorinated biphenyl and pesticide concentrations were low. In adjusted regression models, a ln-unit increase in plasma β-hexachlorocyclohexane concentrations was associated with decreased birth weight (-76g, 95% CI -149, -33), ponderal index (-0.048, 95% CI 0.102, 0.007) and proportion of optimal birth weight (-1.5%, 95% CI -3.6, 0.5) in the whole study population, with stronger associations observed for male infants. Maternal p,p'-dichlorodiphenyldichloroethylene concentrations were associated with reduced ponderal index in male infants (β=-0.171, 95% CI -0.269, -0.074). A ln-unit increase in plasma hexachlorobenzene concentrations was associated with a 5% increase in POBW in male infants (95% CI 0.67, 9.5). Increased urinary barium was associated with increased birth length and POBL and decreased ponderal index in boys. Conversely, urinary concentrations of caesium and rubidium were found to be associated with decreased foetal growth in female infants. This study supports the growing body of evidence regarding the reductions in foetal growth associated with β-hexachlorocyclohexane and p,p'-Dichlorodiphenyldichloroethylene as well as reporting new relationships between metals exposures and birth outcomes. The finding that maternal exposure to barium, strontium, rubidium and caesium was associated with birth outcomes requires confirmation in larger studies. Similarly the apparent differences in susceptibility based on sex of the infant requires further investigation.

Maternal exposure to perfluoroalkyl acids measured in whole blood and birth outcomes in offspring

Perfluoralkyl and polyfluoralkyl substances have been measured in plasma and serum of pregnant women as a measure of prenatal exposure. Increased concentrations of individual perfluoroalkyl acids (PFAAs), (typically perfluorooctanoic acid (PFOA) and perfluoroctane sulfonate (PFOS) have been reported to be associated with reductions in birth weight and other birth outcomes. We undertook a study of 14 PFAAs in whole blood (including PFOS, PFHxS, PFHpA, PFOA, PFNA, PFDA and PFUnDA) from 98 pregnant women in Western Australia from 2008 to 2011. Median concentrations (in μg/L) were: PFOS 1.99; PFHxS 0.33; PFOA 0.86; PFNA 0.30; PFDA 0.12 and PFUnDA 0.08. Infants born to women with the highest tertile of PFHxS exposure had an increased odds of being <95% of their optimal birth weight (OR 3.5, 95% CI 1.1–11.5). Conversely, maternal blood concentrations of PFUnDA were associated with non-significant increases in average birth weight (+102g, 95% CI −41, 245) and significant increases in proportion of optimal birth weight (+4.7%, 95% CI 0.7, 8.8) per ln-unit change. This study has reported a range of PFAAs in the whole blood of pregnant women and suggests that PFHxS and PFUnDA may influence foetal growth and warrant further attention. Additional studies are required to identify the sources of PFAA exposure with a view to prevention, in addition to further studies investigating the long term health effects of these ubiquitous chemicals.

Fetal growth and childhood acute lymphoblastic leukemia: Findings from the childhood leukemia international consortium

Positive associations have been reported between the measures of accelerated fetal growth and risk of childhood acute lymphoblastic leukemia (ALL). We investigated this association by pooling individual-level data from 12 case-control studies participating in the Childhood Leukemia International Consortium. Two measures of fetal growth-weight-for-gestational-age and proportion of optimal birth weight (POBW)-were analysed. Study-specific odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression, and combined in fixed effects meta-analyses. Pooled analyses of all data were also undertaken using multivariable logistic regression. Subgroup analyses were undertaken when possible. Data on weight for gestational age were available for 7,348 cases and 12,489 controls from all 12 studies and POBW data were available for 1,680 cases and 3,139 controls from three studies. The summary ORs from the meta-analyses were 1.24 (95% CI: 1.13, 1.36) for children who were large for gestational age relative to appropriate for gestational age, and 1.16 (95% CI: 1.09, 1.24) for a one-standard deviation increase in POBW. The pooled analyses produced similar results. The summary and pooled ORs for small-for-gestational-age children were 0.83 (95% CI: 0.75, 0.92) and 0.86 (95% CI: 0.77, 0.95), respectively. Results were consistent across subgroups defined by sex, ethnicity and immunophenotype, and when the analysis was restricted to children who did not have high birth weight. The evidence that accelerated fetal growth is associated with a modest increased risk of childhood ALL is strong and consistent with known biological mechanisms involving insulin-like growth factors. © 2013 UICC.

Locally derived traffic-related air pollution and fetal growth restriction: a retrospective cohort study

BackgroundFetal growth restriction has been inconsistently associated with maternal exposure to elevated levels of traffic-related air pollution.ObjectiveWe investigated the relationship between an individualised measure of fetal growth and maternal exposure...

Traffic emissions are associated with reduced fetal growth in areas of Perth, Western Australia: an application of the AusRoads dispersion model

This study, in a region with relatively low industrial activity, used a highly specific marker for traffic emissions, accounted for the inherent fetal growth potential, and used complete record linkage of births, midwife notifications, deaths, hospital morbidity and birth defect records. Clinical records were obtained for pregnancies between 2000 and 2006 in three areas of Perth, Western Australia (n=3,501). We used carbon monoxide as a marker for locally derived traffic emissions, and assessed exposure using the AusRoads dispersion model. Fetal growth was characterised by proportion of optimal birth weight and investigated using multivariate mixed-effects regression. Exposure in the third trimester was associated with a -0.49% (sd=0.23%) change in proportion of optimal birth weight per 10 μg/m(3) increase in locally derived traffic emissions. However, this result was confined to one of the three study areas due to elevated exposure misclassification among women in the other two areas. Among this group, a neonate who would have otherwise attained an optimal birth weight of 3.5 kg would be expected to be born 58 g lighter for an interquartile increase in third trimester exposure, which was approximately half of the effect observed for maternal smoking during pregnancy. We observed an association between maternal exposure to traffic emissions and reduced fetal growth. This effect was supported by sensitivity analyses but only observed in one of the three study areas. Further studies are required to corroborate our results.

Seasonal variation in fetal growth: accounting for sociodemographic, biological, and environmental exposures

We sought to investigate seasonal variation in fetal growth, accounting for important sociodemographic, biological, and environmental exposures. Records of births 1998 through 2006 in Perth, Western Australia were obtained (N = 147,357). We investigated small for gestational age and sex and the proportion of optimal birthweight (POBW) in relation to seasonal exposures (season, temperature, sunlight) by trimester of pregnancy. Adjustment was made for a wide range of risk factors. The POBW for neonates with third trimesters predominantly in summer was 0.18% (0.00-0.36%) lower than for those in winter. POBW decreased by 0.14% (0.01-0.27%) per interquartile range increase in third-trimester temperature (9.15°C). An interquartile range increase in temperature over pregnancy (0.73°C) was associated with an odds ratio of 1.02 (95% confidence interval, 1.00-1.05) for small for gestational age and sex. Reduced fetal growth was associated with elevated ambient temperatures throughout and late in pregnancy, independently of air pollution and other risk factors.

Community-Level Socioeconomic Inequalities in Infants With Poor Fetal Growth in Western Australia, 1984 to 2006

This study describes social and racial inequalities in poor fetal growth in Western Australia between 1984 and 2006. Multilevel multivariate logistic regression was used to investigate relative differences in fetal growth restriction between socioeconomic groups. Fetal growth restriction was defined as having a proportion of optimal birth weight corresponding to less than the 10th percentile for the population. Aboriginal (N = 50,395) and non-Aboriginal (N = 517,073) infants were analyzed separately. There has been an overall decrease in the rate of poor fetal growth during the last 23 years, with a plateau reached in recent years. Aboriginal infants were significantly more likely to have fetal growth restriction than non-Aboriginal infants and social inequalities increased over time, particularly among non-Aboriginal infants. After stratifying by Aboriginality and accounting for important parental sociodemographic characteristics, the community-level socioeconomic gradient remained. This study highlights the misleading nature of observing aggregated rates of poor fetal growth that mask increasing inequalities, and the importance of monitoring trends by social and racial characteristics. It also highlights the concerning finding that almost all improvements in poor fetal growth have occurred in the least disadvantaged communities, with almost no change in the most disadvantaged communities, which is likely to result in further increases in social and racial inequalities.

Western Australian children with acute lymphoblastic leukemia are taller at diagnosis than unaffected children of the same age and sex

Acute lymphoblastic leukemia (ALL) is the commonest childhood malignancy in Australian children. Recently published data from Western Australia suggest a link between proportion of optimal birth weight and the risk of ALL, but few studies have investigated the relationship between growth during infancy and early childhood and risk of leukemia. The aim of this study was to determine whether children diagnosed with ALL in Western Australia were taller at the time of diagnosis than children of the same age and sex in the general population. Records of children diagnosed with ALL between January 1984 and June 2008 were accessed. Height before the commencement of chemotherapy was recorded and compared to the height of population norms derived from the Longitudinal Study of Australian Children. On average, male cases were 0.67 cm (95% CI -0.21, 1.54 cm) taller and female cases were 0.30 cm (95% CI -0.68, 1.28 cm) taller than population controls. Our results suggest that children diagnosed with ALL in Western Australia are slightly taller than their counterparts in the general population. These findings are consistent with at least one previous study. While this increase in height may be too small to be recognizable clinically, it is consistent with the notion that growth factors play a role in the pathogenesis of ALL beyond infancy.

Fetal Growth and Risk of Childhood Acute Lymphoblastic Leukemia: Results From an Australian Case-Control Study

The relation between intrauterine growth and risk of childhood acute lymphoblastic leukemia was investigated in an Australian population-based case-control study that included 347 cases and 762 controls aged <15 years recruited from 2003 to 2006. Information on proportion of optimal birth weight, a measure of the appropriateness of fetal growth, was collected from mothers by questionnaire. Data were analyzed by using logistic regression. Risk of acute lymphoblastic leukemia was positively associated with proportion of optimal birth weight; the odds ratio for a 1-standard-deviation increase in proportion of optimal birth weight was 1.18 (95% confidence interval: 1.04, 1.35) after adjustment for the matching variables and potential confounders. This association was also present among children who did not have a high birth weight, suggesting that accelerated growth, rather than high birth weight per se, is associated with risk of acute lymphoblastic leukemia. Similar associations between proportion of optimal birth weight and acute lymphoblastic leukemia were observed for both sexes and across age groups and leukemia subtypes. Results of this study confirm earlier findings of a positive association between rapidity of fetal growth and subsequent risk of acute lymphoblastic leukemia in childhood, and they are consistent with a role for insulin-like growth factors in the causal pathway.

Association of Birth Outcomes and Maternal, School, and Neighborhood Characteristics with Subsequent Numeracy Achievement

This study investigated the relation between birth characteristics and numeracy attainment at age 8 years. Using a multilevel approach, the authors analyzed all non-Aboriginal singletons born in Western Australia who attended government schools and participated in a Western Australia-wide numeracy test in grade 3 between 1999 and 2005. Appropriateness of intrauterine growth was expressed as the proportion of optimal growth parameters for gestational duration, infant sex, and maternal height and parity, which was derived from a total population of births without risk factors for growth restriction. After the authors controlled for sociodemographic factors, term birth and proportion of optimal head circumference at birth were associated with higher numeracy scores. Increasing proportion of optimal birth length and being firstborn were associated with relatively higher numeracy scores among children born to mothers residing in the most educationally deprived area. The relative advantage of being born first was also higher for children born to single mothers. In contrast, higher Apgar scores and greater proportion of optimal birth weight were associated with a lower relative advantage for children born to single mothers. In summary, term birth and increased growth in head circumference and length are key birth characteristics associated with higher numeracy scores, especially among disadvantaged children.

Fetal growth and the risk of childhood CNS tumors and lymphomas in Western Australia

The etiology of childhood cancers is largely unknown, although the early age at diagnosis has led to particular interest in in utero and perinatal factors. Birth weight is the most frequently studied perinatal factor in relation to risk of childhood cancers, and results have been inconsistent. We investigated whether the risk of CNS tumors and lymphomas in children was associated with three measures of the appropriateness of intra-uterine growth: proportion of optimal birth weight (POBW), birth length (POBL) and weight for length (POWFL). A cohort of 576,633 infants born in Western Australia in 1980-2004 were followed from birth to diagnosis of a CNS tumor (n = 183) or lymphoma (n = 84) before age 15, death, or December 31, 2005, and analyzed with Cox regression. Overall, there was little evidence of any association between fetal growth and risk of CNS tumors, although risk of ependymoma/choroid plexus tumors was positively associated with POBL and negatively associated with POWFL. The risk of Hodgkin and Burkitt lymphoma increased with increasing fetal growth among boys only, whereas the increased risk observed with non-Hodgkin lymphoma was only in girls. These associations between fetal growth and disease risk were also observed among children not classified as high birth weight, suggesting that accelerated growth is more important than birth weight per se. Results were similar when cases were compared with their unaffected siblings, suggesting that the increased growth associated with cancer risk was not general to the family. The associations we observed are consistent with causal pathways involving fetal growth factors.

Fetal Growth and Acute Childhood Leukemia: Looking Beyond Birth Weight

The authors examined the relation between birth weight, intrauterine growth, and risk of childhood leukemia using population-based linked health data from Western Australia. A cohort of 576,593 infants born in 1980-2004 were followed from birth to diagnosis of acute lymphoblastic leukemia (ALL) (n = 243) or acute myeloid leukemia (AML) (n = 36) before their 15th birthday, death, or the end of follow-up (December 31, 2005). Data were analyzed using Cox regression. Risk of ALL was positively associated with the proportion of optimal birth weight--a measure of the appropriateness of fetal growth--particularly among children younger than 5 years; the hazard ratio for a 1-standard-deviation increase in proportion of optimal birth weight was 1.25 (95% confidence interval: 1.07, 1.47). Among children younger than 5 years not classified as having high birth weight (defined as >3,500 g, >3,800 g, and >4,000 g), a 1-unit increase in proportion of optimal birth weight was associated with an approximately 40% increase in ALL risk. This suggests that accelerated growth, rather than high birth weight per se, is involved in the etiology of ALL. These findings are consistent with a role for insulin-like growth factor I in the causal pathway. Findings for AML were inconclusive, probably because of small numbers.