Natasha Nassar

Population-based trends in pregnancy hypertension and pre-eclampsia: an international comparative study

Objective The objective of this study was to compare international trends in pre-eclampsia rates and in overall pregnancy hypertension rates (including gestational hypertension, pre-eclampsia and eclampsia). Design Population data (from birth and/or hospital records) on all women giving birth were available from Australia (two states), Canada (Alberta), Denmark, Norway, Scotland, Sweden and the USA (Massachusetts) for a minimum of 6 years from 1997 to 2007. All countries used the 10th revision of the International Classification of Diseases, except Massachusetts which used the 9th revision. There were no major changes to the diagnostic criteria or methods of data collection in any country during the study period. Population characteristics as well as rates of pregnancy hypertension and pre-eclampsia were compared. Results Absolute rates varied across the populations as follows: pregnancy hypertension (3.6% to 9.1%), pre-eclampsia (1.4% to 4.0%) and early-onset pre-eclampsia (0.3% to 0.7%). Pregnancy hypertension and/or pre-eclampsia rates declined over time in most populations. This was unexpected given that factors associated with pregnancy hypertension such as pre-pregnancy obesity and maternal age are generally increasing. However, there was also a downward shift in gestational age with fewer pregnancies reaching 40 weeks. Conclusion The rate of pregnancy hypertension and pre-eclampsia decreased in northern Europe and Australia from 1997 to 2007, but increased in Massachusetts. The use of a different International Classification of Diseases coding version in Massachusetts may contribute to the difference in trend. Elective delivery prior to the due date is the most likely explanation for the decrease observed in Europe and Australia. Also, the use of interventions that reduce the risk of pregnancy hypertension and/or progression to pre-eclampsia (low-dose aspirin, calcium supplementation and early delivery for mild hypertension) may have contributed to the decline.

The effect of maternal alcohol consumption on fetal growth and preterm birth

Objective  To investigate the relationship between prenatal alcohol exposure and fetal growth and preterm birth and to estimate the effect of dose and timing of alcohol exposure in pregnancy.

Maternal vitamin D status in pregnancy and adverse pregnancy outcomes in a group at high risk for pre-eclampsia.

Please cite this paper as: Shand A, Nassar N, Von Dadelszen P, Innis S, Green T. Maternal vitamin D status in pregnancy and adverse pregnancy outcomes in a group at high risk for pre‐eclampsia. BJOG 2010;117:1593–1598.

Autism spectrum disorders in young children: effect of changes in diagnostic practices.

BACKGROUND It is unclear whether the increase in autism over the past two decades is a real increase or due to changes in diagnosis and ascertainment of autism spectrum disorders (ASDs), which include autism, Asperger syndrome and pervasive developmental disorder not otherwise specified (PDD-NOS). The aim of this study was to examine the trends in ASD over time in Western Australia (WA) and the possible effects and contribution of changes in diagnostic criteria, age at diagnosis, eligibility for service provision based on ASD diagnoses and changes in diagnostic practices. METHODS A population-based study was conducted among the cohort of children born in WA between 1983 and 1999 and diagnosed with ASD between the age of 2 and 8 years up to December 31, 2004. The trend in ASD diagnosis over the study period was assessed by investigating birth cohort and period effects, and examining whether these were modified by age of diagnosis. ASD diagnosis corresponding with changes in diagnostic criteria, funding and service provision over time were also investigated. A subgroup analysis of children aged <or=5 years was also conducted to examine trends in the incidence and age of diagnosis of ASD and intellectual disability (ID) and to investigate the role of changes in diagnostic practices. RESULTS The overall prevalence of ASD among children born between 1983 and 1999 and diagnosed by age 8 was 30 per 10,000 births with the prevalence of autism comprising 21 per 10,000 births. The prevalence of ASD increased by 11.9% per annum, from 8 cases per 10,000 births in 1983 to 46 cases per 10,000 births in 1999. The annual incidence of ASD, based on newly diagnosed ASD cases in each year from 1985 to 2002, increased over the study period. The increase in incidence of ASD appeared to coincide with changes in diagnostic criteria and availability of funding and services in WA, particularly for children aged <5 years. The age-specific rates of autism and PDD-NOS increased over time and the median age of diagnosis for autism decreased from 4 to 3 years of age throughout the 1990s. For children aged <or=5 years the incidence of ASD diagnosis increased significantly from 1992, with an average annual increase of 22%. Similar findings were found for autism. In the corresponding years the incidence of diagnosis of severe ID fell by 10% per annum and mild-moderate ID increased by 3% per annum. CONCLUSIONS The rise in incidence of all types of ASDs by year of diagnosis appears to be related to changes in diagnostic and service provision practices in WA. In children aged <or=5 years, diagnosis of severe ID decreased, but mild-moderate ID increased during the study period. A true increase in ASD cannot be ruled out.

Evidence of a complex association between dose, pattern and timing of prenatal alcohol exposure and child behaviour problems

BACKGROUND There is a lack of evidence regarding the effect of dose, pattern and timing of prenatal alcohol exposure and behaviour problems in children aged 2 years and older. METHODS A 10% random sample of women delivering a live infant in Western Australia (1995-96) were invited to participate in an 8-year longitudinal survey (78% response rate n = 2224); 85% were followed-up at 2 years, 73% at 5 years and 61% at 8 years. Alcohol consumption was classified by combining the overall dose, dose per occasion and frequency to reflect realistic drinking patterns. Longitudinal analysis was conducted using generalized estimating equations (GEE) to investigate the association between child behaviour as measured by the Child Behaviour Checklist at 2, 5 and 8 years of age and prenatal alcohol exposure collected 3 months postpartum for each trimester separately, adjusting for a wide range of confounding factors. RESULTS Low levels of prenatal alcohol were not associated with child behaviour problems. There were increased odds of internalizing behaviour problems following heavy alcohol exposure in the first trimester; anxiety/depression [adjusted odds ratio (aOR) 2.82; 95% confidence interval (CI) 1.07-7.43] and somatic complaints (aOR 2.74; 95% CI 1.47-5.12) and moderate levels of alcohol exposure increased the odds of anxiety/depression (aOR 2.24; 95% CI 1.16-4.34). CONCLUSIONS Prenatal alcohol exposure at moderate and higher levels increased the odds of child behaviour problems with the dose, pattern and timing of exposure affecting the type of behaviour problems expressed. Larger studies with more power are needed to confirm these findings.

Increasing prevalence of hypospadias in Western Australia, 1980-2000

Objectives: Hypospadias, a common birth defect, has shown widespread variation in reported rates and temporal trends across countries over the last 30 years. The aim of this study was to determine the prevalence and trends of hypospadias in an Australian population. Design: Population-based study of all male infants born in Western Australia (WA) between 1980 and 2000 diagnosed with hypospadias and notified to the WA Birth Defects Registry. Main outcome measures: Prevalence of hypospadias, birth outcome and association with other congenital anomalies, stratified by degree-of-severity. Results: 1788 cases of hypospadias were registered in WA in 1980–2000 with an overall prevalence of 34.8 (95% confidence interval (CI): 33.2 to 36.4) cases per 10 000 births. The prevalence increased by 2.0% per annum (95% CI: 1.2% to 2.8%) from 27.9 in 1980 to 43.2 per 10 000 births in 2000 (p<0.001). Hypospadias was mild in 84% of cases, moderate-severe in 11% and unspecified in 5%, with the number of moderate-severe hypospadias almost doubling over time (p<0.01). There were 1465 (82%) cases of isolated hypospadias and 323 (18%) had co-existing anomalies. Infants with co-existing genital (relative risk (RR) 4.5; 95% CI: 3.3 to 6.1) or non-genital (RR 1.5; 95% CI: 1.0 to 2.2) anomalies were more likely to have moderate-severe hypospadias compared with isolated cases. Conclusion: Hypospadias affects one in 231 births and has been reported to have increased significantly over the last 20 years. Future investigation of the aetiology of hypospadias is important to identify potentially modifiable risk factors and ensure optimal male reproductive health in the future.

Effects of maternal serum 25-hydroxyvitamin D concentrations in the first trimester on subsequent pregnancy outcomes in an Australian population

BACKGROUND Low serum 25-hydroxyvitamin D [25(OH)D] concentrations during pregnancy have been associated with adverse pregnancy outcomes in a few studies but not in other studies. OBJECTIVES We assessed the serum 25(OH)D concentration at 10-14 wk of pregnancy and its association with adverse pregnancy outcomes and examined the predictive accuracy. DESIGN In this nested case-control study, we measured serum 25(OH)D in 5109 women with singleton pregnancies who were attending first-trimester screening in New South Wales, Australia. Multivariate logistic regression was conducted to examine the association between low 25(OH)D concentrations and adverse pregnancy outcomes (small for gestational age, preterm birth, preeclampsia, gestational diabetes, miscarriage, and stillbirth). The predictive accuracy of models was assessed. RESULTS The median (IQR) 25(OH)D concentration for the total population was 56.4 nmol/L (43.3-69.8 nmol/L). Serum 25(OH)D concentrations showed significant variation by parity, smoking, weight, season of sampling, country of birth, and socioeconomic status. After adjustment for maternal and clinical risk factors, low 25(OH)D concentrations were not associated with most adverse pregnancy outcomes. The area under the receiver operating characteristic curve (AUC) and likelihood ratio for a composite of severe adverse pregnancy outcomes of 25(OH)D concentrations <25 nmol/L were 0.51 and 1.44, respectively, and, for risk factors alone, were 0.64 and 2.87, respectively. The addition of 25(OH)D information to maternal and clinical risk factors did not improve the ability to predict severe adverse pregnancy outcomes (AUC: 0.64; likelihood ratio: 2.32; P = 0.39). CONCLUSION Low 25(OH)D serum concentrations in the first trimester of pregnancy are not associated with adverse pregnancy outcomes and do not predict complications any better than routinely assessed clinical and maternal risk-factor information.

Increasing Prevalence of Neonatal Withdrawal Syndrome: Population Study of Maternal Factors and Child Protection Involvement

OBJECTIVES. Illicit drug use during pregnancy is an important public health issue, with adverse effects on the newborn and implications for subsequent parenting. The aim of this study was to measure the birth prevalence of neonatal withdrawal syndrome over time, associated maternal characteristics and child protection involvement. METHODS. This is a retrospective cohort study that used linked health and child protection databases for all live births in Western Australia from 1980 to 2005. Maternal characteristics and mental health–and assault-related medical history were assessed by using logistic regression models. RESULTS. The birth prevalence of neonatal withdrawal syndrome increased from 0.97 to a high of 42.2 per 10 000 live births, plateauing after 2002. Mothers with a previous mental health admission, low skill level, Aboriginal status or who smoked during pregnancy were significantly more likely to have an infant with neonatal withdrawal syndrome. These infants were at greater risk for having a substantiated child maltreatment allegation and entering foster care. Increased risk for maltreatment was associated with mothers who were aged <30 years, were from socially disadvantaged backgrounds, Aboriginal status, and had a mental health–or assault-related admission. CONCLUSIONS. There has been a marked increase in neonatal withdrawal syndrome in the past 25 years. Specific maternal characteristics identified should facilitate planning for early identification and intervention for these women. Findings demonstrate an important pathway into child maltreatment and highlight the need for well-supported programs for women who use illicit drugs during pregnancy as well as the need for sustained long-term support after birth.

Autism and intellectual disability are differentially related to sociodemographic background at birth.

Background Research findings investigating the sociodemographics of autism spectrum disorder (ASD) have been inconsistent and rarely considered the presence of intellectual disability (ID). Methods We used population data on Western Australian singletons born from 1984 to 1999 (n = 398,353) to examine the sociodemographic characteristics of children diagnosed with ASD with or without ID, or ID without ASD compared with non-affected children. Results The profiles for the four categories examined, mild-moderate ID, severe ID, ASD without ID and ASD with ID varied considerably and we often identified a gradient effect where the risk factors for mild-moderate ID and ASD without ID were at opposite extremes while those for ASD with ID were intermediary. This was demonstrated clearly with increased odds of ASD without ID amongst older mothers aged 35 years and over (odds ratio (OR) = 1.69 [CI: 1.18, 2.43]), first born infants (OR = 2.78; [CI: 1.67, 4.54]), male infants (OR = 6.57 [CI: 4.87, 8.87]) and increasing socioeconomic advantage. In contrast, mild-moderate ID was associated with younger mothers aged less than 20 years (OR = 1.88 [CI: 1.57, 2.25]), paternal age greater than 40 years (OR = 1.59 [CI: 1.36, 1.86]), Australian-born and Aboriginal mothers (OR = 1.60 [CI: 1.41, 1.82]), increasing birth order and increasing social disadvantage (OR = 2.56 [CI: 2.27, 2.97]). Mothers of infants residing in regional or remote areas had consistently lower risk of ASD or ID and may be linked to reduced access to services or under-ascertainment rather than a protective effect of location. Conclusions The different risk profiles observed between groups may be related to aetiological differences or ascertainment factors or both. Untangling these pathways is challenging but an urgent public health priority in view of the supposed autism epidemic.

Systematic review of first-trimester vitamin D normative levels and outcomes of pregnancy

OBJECTIVE We undertook a systematic review to assess normative levels of vitamin D in early pregnancy and association with subsequent pregnancy outcomes. STUDY DESIGN Medline and Embase databases and reference lists were searched. Inclusion criteria were pregnant populations, blood sample taken during the first trimester, and serum hydroxyvitamin D levels assessed. RESULTS Eighteen studies reported vitamin D levels in first trimester (n = 11-3730), and 5 examined pregnancy outcomes. Mean vitamin D concentrations differed when stratified by ethnicity: white (mean [SD]: 29.4 [11.7] to 73.1 [27.1] nmol/L) and nonwhite (15.2 [12.1] to 43 [12] nmol/L). Most studies used general population cut points to define deficiency and found a large proportion of women deficient. Two articles examined risk of preeclampsia and reported differing findings, whereas 2 of 3 found low levels associated with increased risk of small-for-gestational age births. CONCLUSION There is no clear definition of vitamin D deficiency in pregnancy and insufficient evidence to suggest low vitamin D levels in early pregnancy are associated with adverse pregnancy outcomes.