Disparities between Aboriginal and non-Aboriginal perinatal mortality rates in Western Australia from 1980 to 2015.

BACKGROUND: Perinatal mortality rates are typically higher in Aboriginal than non-Aboriginal populations of Australia. OBJECTIVES: This study aimed to examine the pattern of stillbirth and neonatal mortality rate disparities over time in Western Australia, including an evaluation of these disparities across gestational age groupings. METHODS: All singleton births (≥20 weeks gestation) in Western Australia between 1980 and 2015 were included. Linked data were obtained from core population health datasets of Western Australia. Stillbirth and neonatal mortality rates and percentage changes in the rates over time were calculated by Aboriginal status and gestational age categories. RESULTS: From 1980 to 2015, data were available for 930 926 births (925 715 livebirths, 5211 stillbirths and 2476 neonatal deaths). Over the study period, there was a substantial reduction in both the Aboriginal (19.6%) and non-Aboriginal (32.3%) stillbirth rates. These reductions were evident in most gestational age categories among non-Aboriginal births and in Aboriginal term births. Concomitantly, neonatal mortality rates decreased in all gestational age windows for both populations, ranging from 32.1% to 77.5%. The overall stillbirth and neonatal mortality rate differences between Aboriginal and non-Aboriginal birth decreased by 0.6 per 1000 births and 3.9 per 1000 livebirths, respectively, although the rate ratios (RR 2.51, 95% CI 2.14, 2.94) and (RR 2.94, 95% CI 2.24, 3.85), respectively reflect a persistent excess of Aboriginal perinatal mortality across the study period. CONCLUSIONS: Despite steady improvements in perinatal mortality rates in Western Australia over 3½ decades, the gap between Aboriginal and non-Aboriginal rates remains unchanged in relative terms. There is a continuing, pressing need to address modifiable risk factors for preventable early mortality in Aboriginal populations.

Stillbirth and neonatal death rates across time: the influence of pregnancy terminations and birth defects in a Western Australian population-based cohort study.

BACKGROUND: The stillbirth rate in most high income countries reduced in the early part of the 20(th) century but has apparently been static over the past 2½ decades. However, there has not been any account taken of pregnancy terminations and birth defects on these trends. The current study sought to quantify these relationships using linked Western Australian administrative data for the years 1986-2010. METHODS: We analysed a retrospective, population-based cohort of Western Australia births from 1986 to 2010, with de-identified linked data from core population health datasets. RESULTS: The study revealed a significant decrease in the neonatal death rate from 1986 to 2010 (6.1 to 2.1 neonatal deaths per 1000 births; p < .01), while the overall stillbirth rate remained static. The stillbirth trend was driven by deaths in the extremely preterm period (20-27 weeks; which account for about half of all recorded stillbirths and neonatal deaths), masking significant decreases in the rate of stillbirth at very preterm (28-31 weeks), moderate to late preterm (32-36 weeks), and term (37+ weeks). For singletons, birth defects made up an increasing proportion of stillbirths and decreasing proportion of neonatal deaths over the study period-a shift that appears to have been largely driven by the increase in late pregnancy terminations (20 weeks or more gestation). After accounting for pregnancy terminations, we observed a significant downward trend in stillbirth and neonatal death rates at every gestational age. CONCLUSIONS: Changes in clinical practice related to pregnancy terminations have played a substantial role in shaping stillbirth and neonatal death rates in Western Australia over the 2½ decades to 2010. The study underscores the need to disaggregate perinatal mortality data in order to support a fuller consideration of the influence of pregnancy terminations and birth defects when assessing change over time in the rates of stillbirth and neonatal death.

Changes in Caesarean Delivery Rates in Western Australia from 1995 to 2010 by Gestational Age at Birth.

BACKGROUND: The caesarean delivery rate in the developed world has been increasing. It is not well understood how caesarean delivery rates have changed by gestational age at birth in Western Australia, particularly in relation to the introduction of the early-term delivery guidelines in Australia in 2006. METHODS: Data from the Western Australian Midwives Notification System were used to identify 193,136 singletons born to primiparous women at 34-42 weeks' gestation during 1995-2010. Caesarean delivery rates were calculated by gestational age group (34-36 weeks, 37-38 weeks, and 39-42 weeks) and stratified into pre-labour and in-labour caesarean delivery. The average annual percent change (AAPC) for the caesarean delivery rates was calculated using joinpoint regression. Log-binomial regression was used to estimate the risk of having a caesarean delivery while adjusting for maternal and antenatal factors. RESULTS: Caesarean delivery rates rose steadily from 1995 to 2005 (AAPC = 5.9%, [95% confidence interval (CI) 4.9, 6.9]), but stabilised since then (AAPC = 0.9%, [95% CI -1.9, 3.8]). The rate of in-labour caesarean deliveries rose consistently from 1995 to 2010 across all gestational age groups. The pre-labour caesarean delivery rate rise was most dominant at 37-38 weeks' gestation from 1995 to 2005 (AAPC = 6.8%, [95% CI 5.4, 8.2]), but declined during 2006-10 (AAPC = -4.5, [95% CI -6.7, -2.3]), while at the same time the rate at 39-42 weeks rose slightly. CONCLUSIONS: The rise in pre-labour caesarean deliveries during 1995-2005 occurred predominantly at 37-38 weeks' gestation, but declined again from 2006 to 2010. This suggests that the recently developed Australian early-term delivery guidelines may have had some success in reducing early-term deliveries in Western Australia.

Trends in pre-existing mental health disorders among parents of infants born in Western Australia from 1990 to 2005.

OBJECTIVE: To determine the prevalence of prior and current mental health disorders in parents, including trends over time. DESIGN: retrospective population cohort study using de-identified linked health data. SETTING: Population of Western Australia. SUBJECTS: All parents of infants born in WA between 1990 and 2005. MAIN OUTCOME MEASURES: Prevalence of prior mental health disorders in parents by birth 2013 and by parent and child characteristics, including Aboriginality, maternal age, socioeconomic status and diagnostic groups. RESULTS: From 1990 to 2005, there was an increase in prevalence of prior mental health disorders in mothers, from 76 per 1000 births in 1990 to 131 per 1000 births in 2005 (3.7% increase per 2013 in the odds of children being born to mothers with a prior mental health disorder). There was also a 4.7% increase in odds per 2013 in the prevalence of mental health contacts that had taken place in the 12 months before the birth 2013 in mothers. In addition, there was an increase in prevalence of prior mental health disorders in fathers, from 56 per 1000 births in 1990 to 88 per 1000 births in 2005 (3.1% increase in odds per 2013). The diagnostic group with the highest prevalence in both mothers and fathers was substance-related disorders. CONCLUSIONS: From 1990 to 2005, there was an increase in prevalence of parents with a prior history of mental health disorders in WA. General practitioners and mental health workers can play an important role in identifying mental illness and in working with families to offer early intervention, referral and support.

Are women with major depression in pregnancy identifiable in population health data?

BACKGROUND: Although record linkage of routinely collected health datasets is a valuable research resource, most datasets are established for administrative purposes and not for health outcomes research. In order for meaningful results to be extrapolated to specific populations, the limitations of the data and linkage methodology need to be investigated and clarified. It is the objective of this study to investigate the differences in ascertainment which may arise between a hospital admission dataset and a dispensing claims dataset, using major depression in pregnancy as an example. The safe use of antidepressants in pregnancy is an ongoing issue for clinicians with around 10% of pregnant women suffer from depression. As the birth admission will be the first admission to hospital during their pregnancy for most women, their use of antidepressants, or their depressive condition, may not be revealed to the attending hospital clinicians. This may result in adverse outcomes for the mother and infant. METHODS: Population-based de-identified data were provided from the Western Australian Data Linkage System linking the administrative health records of women with a delivery to related records from the Midwives' Notification System, the Hospital Morbidity Data System and the national Pharmaceutical Benefits Scheme dataset. The women with depression during their pregnancy were ascertained in two ways: women with dispensing records relating to dispensed antidepressant medicines with an WHO ATC code to the 3rd level, pharmacological subgroup, 'N06A Antidepressants'; and, women with any hospital admission during pregnancy, including the birth admission, if a comorbidity was recorded relating to depression. RESULTS: From 2002 to 2005, there were 96698 births in WA. At least one antidepressant was dispensed to 4485 (4.6%) pregnant women. There were 3010 (3.1%) women with a comorbidity related to depression recorded on their delivery admission, or other admission to hospital during pregnancy. There were a total of 7495 pregnancies identified by either set of records. Using data linkage, we determined that these records represented 6596 individual pregnancies. Only 899 pregnancies were found in both groups (13.6% of all cases). 80% of women dispensed an antidepressant did not have depression recorded as a comorbidity on their hospital records. A simple capture-recapture calculation suggests the prevalence of depression in this population of pregnant women to be around 16%. CONCLUSION: No single data source is likely to provide a complete health profile for an individual. For women with depression in pregnancy and dispensed antidepressants, the hospital admission data do not adequately capture all cases.

Neonatal outcomes after preterm birth by mothers' health insurance status at birth: a retrospective cohort study.

BACKGROUND: Publicly insured women usually have a different demographic background to privately insured women, which is related to poor neonatal outcomes after birth. Given the difference in nature and risk of preterm versus term births, it would be important to compare adverse neonatal outcomes after preterm birth between these groups of women after eliminating the demographic differences between the groups. METHODS: The study population included 3085 publicly insured and 3380 privately insured, singleton, preterm deliveries (32-36 weeks gestation) from Western Australia during 1998-2008. From the study population, 1016 publicly insured women were matched with 1016 privately insured women according to the propensity score of maternal demographic characteristics and pre-existing medical conditions. Neonatal outcomes were compared in the propensity score matched cohorts using conditional log-binomial regression, adjusted for antenatal risk factors. Outcomes included Apgar scores less than 7 at five minutes after birth, time until establishment of unassisted breathing (>1 minute), neonatal resuscitation (endotracheal intubation or external cardiac massage) and admission to a neonatal special care unit. RESULTS: Compared with infants of privately insured women, infants of publicly insured women were more likely to receive a low Apgar score (ARR = 2.63, 95% CI = 1.06-6.52) and take longer to establish unassisted breathing (ARR = 1.61, 95% CI = 1.25-2.07), yet, they were less likely to be admitted to a special care unit (ARR = 0.84, 95% CI = 0.80-0.87). No significant differences were evident in neonatal resuscitation between the groups (ARR = 1.20, 95% CI = 0.54-2.67). CONCLUSIONS: The underlying reasons for the lower rate of special care admissions in infants of publicly insured women compared with privately insured women despite the higher rate of low Apgar scores is yet to be determined. Future research is warranted in order to clarify the meaning of our findings for future obstetric care and whether more equitable use of paediatric services should be recommended.

Delivery at 37 weeks' gestation is associated with a higher risk for child behavioural problems.

BACKGROUND: Advances in obstetric care have been accompanied by increasing rates of intervention which often involve elective delivery at 37 weeks, soon after term gestation has been achieved. AIM: The aim of this study was to examine the behavioural sequelae for children born at this early term gestational age compared with those born at later weeks. METHODS: The Western Australian Pregnancy Cohort (Raine) Study provided comprehensive obstetric data from 2900 pregnancies. Offspring were followed up at ages two, five, eight, 10, 14 and 17 years using the parent report Child Behaviour Checklist (CBCL) with clinical cutoffs for overall, internalising (withdrawn, somatic complaints, anxious/depressed) and externalising (delinquent, aggressive) behaviour (T-score ≥ 60). We used longitudinal logistic regression models incorporating generalised estimating equations (GEE) with step-wise adjustment for ante-, peri- and postnatal confounding factors. RESULTS: Approximately 9% of our cohort was born within the range of 37(0/7) and 37(6/7)  weeks. Those born at 37 weeks' gestation were at increased risk for overall (OR = 1.43, 95% CI = 1.02, 2.01) and externalising (OR = 1.42, 95% CI = 1.01, 2.01) behavioural problems in the fully adjusted model when compared with infants born from 39 weeks onwards. Infants born late preterm (34-36 weeks) and at 38 weeks did not show a significantly increased risk for behavioural problems. CONCLUSION: Infants born at 37 weeks' gestation are at increased risk for behavioural problems over childhood and adolescence compared with those born later in gestation. We suggest that 37 weeks' gestation may not be the optimal cutoff for defining perinatal risk as it applies to behavioural development.

Dispensing patterns and pregnancy outcomes for women dispensed selective serotonin reuptake inhibitors in pregnancy.

BACKGROUND: The safety of selective serotonin reuptake inhibitors (SSRIs) during pregnancy remains uncertain. The purpose of this study was to investigate dispensing patterns and pregnancy outcomes for women dispensed an SSRI in pregnancy. METHODS: Using data linkage of population-based health datasets from Western Australia and a national pharmaceutical claims dataset, our study included 123,405 pregnancies from 2002 to 2005. There were 3764 children born to 3703 women who were dispensed an SSRI during their pregnancy. RESULTS: A total of 42.3% of the women were dispensed an SSRI in each trimester, and 97.6% of the women used the same SSRI throughout the first trimester without switching. The women who were dispensed an SSRI were more likely to give birth prematurely (adjusted odds ratio [aOR], 1.4; 95% confidence interval [CI], 1.2-1.7), to have smoked during the pregnancy (OR, 1.9; 95% CI, 1.8-2.1), and parity>1 (OR, 1.7; 95% CI, 1.5-1.8). The singletons were found to have a lower birth weight than expected when other factors were taken into account (OR, 1.2; 95% CI, 1.1-1.3). There was an increased risk of major cardiovascular defects (OR, 1.6; 95% CI, 1.1-2.3). The children of women dispensed citalopram during the first trimester had an increased risk of vesicoureteric reflux (OR, 3.1; 95% CI, 1.3-7.6). Children born to women dispensed sertraline had a higher mean birth weight than those born to women dispensed citalopram, paroxetine, or fluoxetine. This pattern was also seen in birth length. CONCLUSIONS: Most women were dispensed the same SSRI throughout their pregnancy. We have confirmed previous findings with an increased risk of cardiovascular defects and preterm birth. New findings requiring confirmation include an increased risk of vesicoureteric reflux with the use of citalopram.

Prenatal stress and risk of behavioral morbidity from age 2 to 14 years: the influence of the number, type, and timing of stressful life events.

The maternal experience of stressful events during pregnancy has been associated with a number of adverse consequences for behavioral development in offspring, but the measurement and interpretation of prenatal stress varies among reported studies. The Raine Study recruited 2900 pregnancies and recorded life stress events experienced by 18 and 34 weeks' gestation along with numerous sociodemographic data. The mother's exposure to life stress events was further documented when the children were followed-up in conjunction with behavioral assessments at ages 2, 5, 8, 10, and 14 years using the Child Behavior Checklist. The maternal experience of multiple stressful events during pregnancy was associated with subsequent behavioral problems for offspring. Independent (e.g., death of a relative, job loss) and dependent stress events (e.g., financial problems, marital problems) were both significantly associated with a greater incidence of mental health morbidity between age 2 and 14 years. Exposure to stressful events in the first 18 weeks of pregnancy showed similar associations with subsequent total and externalizing morbidity to events reported at 34 weeks of gestation. These results were independent of postnatal stress exposure. Improved support for women with chronic stress exposure during pregnancy may improve the mental health of their offspring in later life.

Breastfeeding and early child development: a prospective cohort study.

AIM: Breastfeeding has been associated with multiple developmental advantages for the infant; however, there have also been a number of studies that find no significant benefits to child development. We examined the relationship between breastfeeding for 4 months or longer and child development at age 1, 2 and 3 years. METHODS: Women were enrolled in the Western Australian Pregnancy Cohort (Raine) Study (N = 2900) and their live born children (N = 2868) were followed to the age of 3 years (N = 2280). Infant feeding data were collected at each age, and the mothers completed the Infant/Child Monitoring Questionnaire (IMQ), which measures progress towards developmental milestones in the domains of gross and fine motor skills, adaptability, sociability and communication. Factors adjusted for in multivariable analyses included maternal sociodemographic characteristics and stressful life events. RESULTS: Infants breastfed for 4 months or longer had significantly higher mean scores (representing better functioning) for fine motor skills at age 1 and 3, significantly higher adaptability scores up to age two, and higher communication scores at age 1 and 3 years. Infants who were breastfed for <4 months were more likely to have at least one atypical score across the five developmental domains than those who were breastfed for 4 months or longer. CONCLUSION: Although our effect sizes were small, breastfeeding for 4 months or longer was associated with improved developmental outcomes for children aged one to 3 years after adjustment for multiple confounding factors.

The long-term effects of breastfeeding on child and adolescent mental health: a pregnancy cohort study followed for 14 years.

OBJECTIVES: To determine whether there was an independent effect of breastfeeding on child and adolescent mental health. STUDY DESIGN: The Western Australian Pregnancy Cohort (Raine) Study recruited 2900 pregnant women and followed the live births for 14 years. Mental health status was assessed by the Child Behaviour Checklist (CBCL) at 2, 6, 8, 10, and 14 years. Maternal pregnancy, postnatal, and infant factors were tested in multivariable random effects models and generalized estimating equations to examine the effects of breastfeeding duration on mental health morbidity. RESULTS: Breastfeeding for less than 6 months compared with 6 months or longer was an independent predictor of mental health problems through childhood and into adolescence. This relationship was supported by the random effects models (increase in total CBCL score: 1.45; 95% confidence interval 0.59, 2.30) and generalized estimating equation models (odds ratio for CBCL morbidity: 1.33; 95% confidence interval 1.09, 1.62) showing increased behavioral problems with shorter breastfeeding duration. CONCLUSION: A shorter duration of breastfeeding may be a predictor of adverse mental health outcomes throughout the developmental trajectory of childhood and early adolescence.

Social and racial inequalities in preterm births in Western Australia, 1984 to 2006.

Preterm birth is associated with a range of childhood morbidities and in industrialised societies is the primary cause of infant mortality. Social and racial inequalities in preterm birth have been reported in North America, UK, Europe and New Zealand. This study utilised population-level data to investigate social and racial inequalities in preterm birth among Aboriginal and non-Aboriginal infants in Western Australia. All live, singleton births between 1984 and 2006 (n = 567 468) were included, and multilevel multivariable logistic regression was used to investigate relative differences in preterm infants between socio-economic groups. Aboriginal and non-Aboriginal infants were analysed separately. The prevalence of preterm births increased from 7.1% in 1984-88 to 7.5% in 1999-2003, before decreasing to 7.2% in 2004-06. Inequalities in preterm births between Aboriginal and non-Aboriginal infants increased over time, with the percentage of preterm births being almost twofold higher for Aboriginal infants (14.8%), compared with non-Aboriginal infants (7.6%). A significant portion of the disparity between Aboriginal and non-Aboriginal infants is attributable to parental socio-economic and demographic characteristics, though the disparity continues to persist even after adjustment for these factors. While the overall rates of preterm birth in Western Australia have remained fairly static over the last two decades, the disparity between Aboriginal and non-Aboriginal infants has increased and is now similar to inequalities seen 20 years ago. These findings highlight a major public health issue that should be of great concern, given the short- and long-term morbidities and complications associated with preterm birth.

Linking a pharmaceutical claims database with a birth defects registry to investigate birth defect rates of suspected teratogens.

PURPOSE: Data linkage of population administrative data is being investigated as a tool for pharmacovigilance in pregnancy in Australia. Records of prescriptions of known or suspected teratogens dispensed to pregnant women have been linked to a birth defects registry to determine if defects associated with medicine exposure can be detected. METHODS: The Pharmaceutical Benefits Scheme is a national claims database that has been linked with population-based data to extract linkages for women with a pregnancy event in Western Australia from 2002 to 2005 (n = 106 074). Records of births to the women who were dispensed medicines in categories D or X of the Australian ADEC pregnancy risk category were linked to the Birth Defects Registry of Western Australia. Population rates of registered birth defects per 1000 births were calculated for each medicine. RESULTS: There were 47 medicines dispensed at least once during pregnancy with 23 associated with a registered birth defect to a woman dispensed the medicine. When the birth defect rate for each medicine was compared with the rate for all other women not dispensed that medicine, most medicines showed an increased risk. Medicines with the higher risks were medroxyprogesterone acetate (OR: 1.8; 95%CI: 1.4-2.3), follitropin alfa (OR: 2.5; 95%CI: 1.2-5.0), carbamazepine (OR: 3.1; 95%CI: 1.7-5.6) and enalapril maleate (OR: 8.1; 95%CI: 1.6-41.7). CONCLUSION: Many known associations between medicines and birth defects were identified, suggesting that linked administrative data could be an important means of pharmacovigilance in pregnancy in Australia.