Trends in early gestation stillbirths and neonatal deaths in New South Wales, Australia 2002-2019.

BACKGROUND: Little research has focused on understanding trends in early gestation (20-27 weeks) stillbirths and neonatal deaths. AIMS: To examine trends in early gestation stillbirths and neonatal deaths in New South Wales (NSW), Australia. MATERIALS AND METHODS: Population-based cohort study of all births ≥20 weeks gestation among female NSW residents during 2002 to 2019, induced pregnancy terminations excluded. Stillbirth rates by gestational age and birth year were calculated per 1000 fetuses-at-risk (FAR). Neonatal death rates by gestational age and birth year were calculated per 1000 live births. Linear regression was used to examine trends in stillbirth and neonatal death rates among all, singleton and twin births. RESULTS: Declining trends in early gestation stillbirth and neonatal death rates were found. Stillbirth rates decreased from 1.9 and 0.9/1000 FAR in 2002 to 1.6 and 0.7 in 2019 for 20-23 and 24-27 week groups, respectively. Neonatal rates decreased from 940 and 315/1000 live births in 2002 to 925 and 189 in 2019 for the 20-23 and 24-27 week groups, respectively. Among singleton births, declining trends in stillbirth and neonatal death rates across all age groups were observed, except for 37-38 week stillbirths. No trends in twin stillbirth rates were found across gestational age groups, although a decreasing trend was observed for 20-23 week twin neonatal deaths. CONCLUSIONS: Trends in early gestation stillbirth and neonatal deaths have declined in recent decades in NSW but further efforts are needed to reduce both early and late gestation stillbirth rates among twin births.

Maternal factors and risk of spontaneous preterm birth due to high ambient temperatures in New South Wales, Australia.

BACKGROUND: Exposure to high ambient temperatures has been shown to increase the risk of spontaneous preterm birth. Determining which maternal factors increase or decrease this risk will inform climate adaptation strategies. OBJECTIVES: This study aims to assess the risk of spontaneous preterm birth associated with exposure to ambient temperature and differences in this relationship between mothers with different health and demographic characteristics. METHODS: We used quasi-Poisson distributed lag non-linear models to estimate the effect of high temperature-measured as the 95th percentile of daily minimum, mean and maximum compared with the median-on risk of spontaneous preterm birth (23-36 weeks of gestation) in pregnant women in New South Wales, Australia. We estimated the cumulative lagged effects of daily temperature and analyses on population subgroups to assess increased or decreased vulnerability to this effect. RESULTS: Pregnant women (n = 916,678) exposed at the 95th percentile of daily mean temperatures (25ºC) had an increased risk of preterm birth (relative risk 1.14, 95% confidence interval 1.07, 1.21) compared with the median daily mean temperature (17℃). Similar effect sizes were seen for the 95th percentile of minimum and maximum daily temperatures compared with the median. This risk was slightly higher among women with diabetes, hypertension, chronic illness and women who smoked during pregnancy. CONCLUSIONS: Higher temperatures increase the risk of preterm birth and women with pre-existing health conditions and who smoke during pregnancy are potentially more vulnerable to these effects.

Training in obstetric anal sphincter injuries in Australia and New Zealand: A survey of Royal Australian and New Zealand College of Obstetricians and Gynaecologists trainees.

BACKGROUND: Training in obstetric anal sphincter injuries (OASIS) in Australia and New Zealand relies upon consultant teaching and has not previously been assessed. AIMS: The aims of this study are to establish if training in OASIS is consistent and optimal in Australia and New Zealand and to evaluate trainee perspectives on supervision and teaching, along with confidence in repairing OASIS. MATERIALS AND METHODS: A descriptive cross-sectional study was performed. Royal Australian and New Zealand College of Obstetricians and Gynaecologists trainees were sent a 21-question survey. The survey was distributed to 725 trainees, and 132 trainees provided complete responses (18.2%). The main outcome measures were (i) comparison of confidence in performing a caesarean section versus OASIS repair and (ii) descriptive analysis of views towards training and suggestions for improvement. RESULTS: Trainees were significantly more confident in performing a caesarean section independently compared to OASIS repair (P < 0.05). This was the case for all year groups. Confidence increased with each year of training. Only 62% reported credentialing at their site. Whereas 50% reported training at the time of first unsupervised repair as good or excellent, 22.7% felt it was suboptimal and 2.3% unsatisfactory; 75.8% had attended a workshop; 38.6% requested mandatory workshops. Requests included that workshops be yearly, include video training and be required at consultant level. Trainees asked for supervision despite credentialing and for separate credentialing for 3A/B- and 3C/4th-degree tears. CONCLUSIONS: Trainees have increasing confidence in their ability to independently perform OASIS repairs throughout training. They requested that improvements be made to training and that there be an increase in structured teaching.

A study of pregnancy after endometrial ablation using linked population data.

INTRODUCTION: Endometrial ablation encapsulates a range of procedures undertaken to destroy the endometrial lining of the uterus as a treatment for heavy menstrual bleeding in women who no longer wish to bear children. Pregnancy following ablation, while unlikely, can occur and may carry higher rates of complications. The aim of this study was to identify factors associated with post-endometrial ablation pregnancy and to describe pregnancy and birth outcomes for post-endometrial ablation pregnancies. MATERIAL AND METHODS: This population-based data linkage study included all female residents of New South Wales, Australia, aged 15-50 years with a hospital admission between July 2001 to June 2014 who birthed between July 2001 and June 2015. Cox proportional hazard regression was used to estimate associations between women's characteristics and post-endometrial ablation pregnancy of at least 20 weeks' gestation. Descriptive statistics were used to characterize pregnancy and birth outcomes. RESULTS: Of 18 559 women with an endometrial ablation, 575 (3.1%) had a post-ablation pregnancy of at least 20 weeks' gestation. Nulliparity (adjusted hazard ratio [aHR] 12.2, 95% confidence interval [CI] 9.1-16.2), older age (35-39 years: aHR 0.39, 95% CI 0.29-0.51; 40-44 years: aHR 0.06, 95% CI 0.04-0.11), marital status (single: aHR 0.67, 95% CI 0.55-0.83; widowed/divorced/separated: aHR 0.58, 95% CI 0.36-0.94) and a diagnosis of heavy menstrual bleeding (aHR 0.09, 95% CI 0.07-0.13) were associated with post-ablation pregnancy. There were high rates of cesarean delivery (43%), preterm birth (13%), twin or higher order pregnancies (9%) and stillbirth (13.3/1000 births) among these post-ablation pregnancies. CONCLUSIONS: Nulliparity at the time of endometrial ablation is associated with increased risk of post-ablation pregnancy, highlighting the importance of careful discussion and consideration of treatment options for heavy menstrual bleeding.

Rates of neonatal morbidity by maternal region of birth and gestational age in New South Wales, Australia 2003-2016.

INTRODUCTION: Research suggests that neonatal morbidity differs by maternal region of birth at different gestational ages. This study aimed to determine the overall and gestation-specific risk of neonatal morbidity by maternal region of birth, after adjustment for maternal, infant and birth characteristics, for women giving birth in New South Wales, Australia, from 2003 to 2016. MATERIAL AND METHODS: The study utilized a retrospective cohort study design using linked births, hospital and deaths data. Modified Poisson regression was used to determine risk with 95% confidence intervals (95% CI) of neonatal morbidity by maternal region of birth, overall and at each gestational age, compared with Australian or New Zealand-born women giving birth at 39 weeks. RESULTS: There were 1 074 930 live singleton births ≥32 weeks' gestation that met the study inclusion criteria, and 44 394 of these were classified as morbid, giving a neonatal morbidity rate of 4.13 per 100 live births. The gestational age-specific neonatal morbidity rate declined from 32 weeks' gestation, reaching a minimum at 39 weeks in all maternal regions of birth. The unadjusted neonatal morbidity rate was highest in South Asian-born women at most gestations. Adjusted rates of neonatal morbidity between 32 and 44 weeks were significantly lower for babies born to East (adjusted relative risk [aRR] 0.65, 95% CI 0.62-0.68), South-east (aRR 0.76, 95% CI 0.73-0.79) and West Asian-born (aRR 0.93, 95% CI 0.88-0.98) mothers, and higher for babies of Oceanian-born (aRR 1.11, 95% CI 1.04-1.18) mothers, compared with Australian or New Zealand-born mothers. Babies of African, Oceanian, South Asian and West Asian-born women had a lower adjusted risk of neonatal morbidity than Australian or New Zealand-born women until 37 or 38 weeks' gestation, and thereafter an equal or higher risk in the term and post-term periods. CONCLUSIONS: Maternal region of birth is an independent risk factor for neonatal morbidity in New South Wales.

Determining a strategy to reduce smoking in pregnancy.

BACKGROUND: Further efforts, informed by current data, are needed to reduce smoking during pregnancy. AIMS: To describe trends in smoking during pregnancy and identify regions most likely to benefit from targeted smoking cessation interventions, in New South Wales (NSW), Australia. MATERIALS AND METHODS: All women who gave birth in NSW between 1994 and 2016 were included. Smoking status was identified from the Perinatal Data Collection. For births between 2012 and 2016, women were grouped into Local Health District (LHD) of residence, and smoking rates calculated. The impacts of a hypothetical smoking cessation intervention in four LHDs with (i) high smoking rates and (ii) high numbers of smokers, were compared. RESULTS: The overall smoking rate during pregnancy decreased from 22.1% in 1994 to 8.3% in 2016. [Correction added on 13 August 2020, after first online publication: the overall smoking rate during pregnancy in 1994 has been corrected from 14.5% to 22.1%.]. The decrease was lowest among women living in the most socioeconomically disadvantaged areas (41%) and highest among those living in the most advantaged areas (83%). Between 2012 and 2016, over half the women who smoked during pregnancy lived in one of four LHDs. Only 1% of women reporting smoking during pregnancy resided in the LHD with the highest smoking rate (34.7%). A simulated intervention targeting only four regions showed greater effect on the statewide smoking rate when targeting LHDs with high numbers of smokers rather than high smoking rates. CONCLUSIONS: Despite decreases in rates of smoking during pregnancy, there was evidence of geographic clustering of smokers. The greatest reduction in overall smoking may come from interventions targeting the four LHDs with the highest number of smokers.

Childhood health and education outcomes following early term induction for large-for-gestational age: A population-based record linkage study.

INTRODUCTION: There is debate about optimal management of pregnancies with a large-for-gestational age baby. A recent randomized controlled trial reported that early term induction of labor reduced cesarean section rates and infant morbidity. However, long term childhood outcomes have not been assessed. The aim of this study was to assess maternal, neonatal and child health and education outcomes for large-for-gestational age babies induced at 37-38 weeks' gestation. MATERIAL AND METHODS: Population-based record linkage study of term (37+ weeks), cephalic-presenting singleton pregnancies with a large-for-gestational age baby in New South Wales, Australia, 2002-2006. Linked birth, hospital, mortality and education data were used with at least 9 years follow up from birth. Exposure was induction of labor at 37-38 weeks, compared to expectant management (spontaneous birth at ≥37 weeks and planned births at ≥39 weeks). Relative risks and 95% confidence intervals were estimated using Modified Poisson regression with robust variance. RESULTS: Among 10 174 eligible pregnancies, 412 (4.0%) had an induction at 37-38 weeks. Women in the induction group were less likely to have a cesarean section (RR: 0.65, 95% CI: 0.51-0.82). Infants had higher rates of: low Apgar scores, birth trauma, neonatal jaundice and phototherapy use, and admission to special care nursery or neonatal intensive care than their expectantly managed counterparts. As children, they had higher rates of hospital admission (RR: 1.16, 95% CI: 1.04-1.30) and special needs (RR: 1.98, 95% CI: 1.12-3.50). However, by age 8 there was no difference in overall literacy and numeracy achievement. CONCLUSIONS: Although women who had an early term labor induction with large-for-gestational age were less likely to have a cesarean section, the increased risk of neonatal morbidities and additional healthcare utilization suggests the need for caution in early induction of large-for-gestational age babies before 39 weeks' gestation.

Outcomes associated with transfusion in low-risk women with obstetric haemorrhage.

BACKGROUND AND OBJECTIVES: Obstetric haemorrhage is associated with increased blood transfusion, morbidity and health service usage in women. While the use of transfusion in actively bleeding patients is supported, there is little evidence for the use of blood as treatment in the nonbleeding patient following obstetric haemorrhage. Transfusion may expose women to increased morbidity. This study aims to compare outcomes between low-risk women receiving no or 1-2 units of blood in the context of obstetric haemorrhage. MATERIALS AND METHODS: The study population included women giving birth in hospital in New South Wales, Australia, between July 2006 and December 2010, with a diagnosis of obstetric haemorrhage. Women with medical or obstetric conditions making them high risk were excluded, as were women receiving more than 2 units of blood. Data were obtained from linked hospital, birth and blood bank databases. Propensity score matching was used to compare outcomes between transfused and nontransfused women in order to estimate the impact of the transfusion itself on outcomes. RESULTS: There were 14989 women with obstetric haemorrhage, of whom, 1702 received a transfusion, including 1069 receiving a transfusion of 1-2 units. Women receiving transfusion were more likely to experience severe maternal morbidity (relative risk 7·0, 95% Confidence interval (2·8, 17·8)), be admitted to intensive care (RR 2·1 95% CI(1·2, 3·8)), and have a length of stay >5 days (RR 2·0, 95% CI (1·6, 2·5)). CONCLUSIONS: Small volume transfusion in the context of obstetric haemorrhage among low-risk women is associated with poorer maternal outcomes and increased healthcare utilisation.

Assessing the effect of risk factors on rates of obstetric transfusion over time using two methodological approaches.

BACKGROUND: While red blood cell transfusion rates have declined in most Australian medical specialties, obstetric transfusion rates have instead been increasing. Obstetric transfusions are mostly linked to postpartum haemorrhage, the rates of which have also increased over time. This study used two methodological approaches to investigate recent trends in obstetric transfusion in New South Wales (NSW) and the extent to which this was influenced by changing maternal and pregnancy characteristics. METHODS: Linked birth and hospital records were used to examine rates of red blood cell transfusion in the postpartum period for mothers giving birth in NSW hospitals from 2005 to 2015. Logistic regression models were run to examine the contribution of maternal and pregnancy risk factors to changing rates of transfusion. Risk factors were divided into "pre-pregnancy" and "pregnancy related". Crude and adjusted estimates of the effect of year of birth on obstetric transfusion rates were compared to assess the effect of risk factors on rates over time using two approaches. The first compared actual and predicted odds ratios of transfusion for each year. The second compared the observed increase in transfusion rate with that predicted after controlling for the risk factors. RESULTS: Among 935,659 births, the rate of obstetric transfusion rose from 13 per 1000 births in 2005 to 17 in 2011, and remained stable until 2015. From 2005 to 2015, postpartum haemorrhage increased from 74 to 114 per 1000 births. Compared with the rate in 2005, the available maternal and pregnancy characteristics only partially explained the change in rate of transfusion by 2015 (Method 1, crude odds ratio 1.39 (95% CI 1.25, 1.56); adjusted odds ratio 1.29 (95% CI 1.15, 1.45)). After adjustment for maternal and pregnancy characteristics, obstetric transfusion incidence was predicted to increase by 10.3%, but a 38.7% increase was observed (Method 2). CONCLUSION: Rates of obstetric transfusion have stabilised after a period of increase. The trend could not be fully explained by measured maternal and pregnancy characteristics with either of the two approaches. Further investigation of rates and maternal and clinical risk factors will help to inform and improve obstetric blood product use.

Variation in clinical decision-making for induction of labour: a qualitative study.

BACKGROUND: Unexplained variation in induction of labour (IOL) rates exist between hospitals, even after accounting for casemix and hospital differences. We aimed to explore factors that influence clinical decision-making for IOL that may be contributing to the variation in IOL rates between hospitals. METHODS: We undertook a qualitative study involving semi-structured, audio-recorded interviews with obstetricians and midwives. Using purposive sampling, participants known to have diverse opinions on IOL were selected from ten Australian maternity hospitals (based on differences in hospital IOL rate, size, location and case-mix complexities). Transcripts were indexed, coded, and analysed using the Framework Approach to identify main themes and subthemes. RESULTS: Forty-five participants were interviewed (21 midwives, 24 obstetric medical staff). Variations in decision-making for IOL were based on the obstetrician's perception of medical risk in the pregnancy (influenced by the obstetrician's personality and knowledge), their care relationship with the woman, how they involved the woman in decision-making, and resource availability. The role of a 'gatekeeper' in the procedural aspects of arranging an IOL also influenced decision-making. There was wide variation in the clinical decision-making practices of obstetricians and less accountability for decision-making in hospitals with a high IOL rate, with the converse occurring in hospitals with low IOL rates. CONCLUSION: Improved communication, standardised risk assessment and accountability for IOL offer potential for reducing variation in hospital IOL rates.

Maternal and neonatal outcomes following abnormally invasive placenta: a population-based record linkage study.

INTRODUCTION: Abnormally invasive placenta involves abnormal adherence of the placenta to the myometrium and is associated with severe pregnancy complications such as blood transfusion and hysterectomy. Knowledge of outcomes has been limited by small sample sizes and a focus on maternal rather than neonatal outcomes. This study uses population-level data collected over 10 years to investigate maternal and neonatal outcomes and trends in incidence of abnormally invasive placenta (also known as placenta accreta, increta and percreta). MATERIAL AND METHODS: A population-based record linkage study was performed, including all women who gave birth in New South Wales, Australia, between 2003 and 2012. Data were obtained from birth records, hospital admissions and deaths registrations. Modified Poisson regression models, adjusted for confounding factors, were used to quantify the effect of abnormally invasive placenta on adverse maternal and neonatal outcomes. RESULTS: Abnormally invasive placenta was significantly associated with morbidity for mothers (adjusted relative risk 17.6, 99% confidence interval 14.5-21.2) and infants (adjusted relative risk 3.1, 99% confidence interval 2.7-3.5). Abnormally invasive placenta increased risk of stillbirth (relative risk 5.4, 99% confidence interval 4.0-7.3) and neonatal death (relative risk 8.0, 99% confidence interval 1.5-41.6). The overall rate of abnormally invasive placenta was 24.8 per 10 000 deliveries, and 22.7 per 10 000 among primiparae. Incidence increased by 30%, from 20.6 to 26.9 per 10 000, over the 10-year study period. CONCLUSIONS: Abnormally invasive placenta substantially increases the risk of severe adverse outcomes for mothers and babies, and the incidence is increasing. Delivery should occur in tertiary hospitals equipped with neonatal intensive care units. Clinicians should be cognizant of the risks, particularly to infants, and maintain a high index of suspicion of abnormally invasive placenta, including in primiparae.

Induction of labour practices in New South Wales hospitals: Before and after a statewide policy.

Midwifery Unit Managers completed surveys in 2008 and 2014 to determine methods of induction of labour. There was an increase in balloon catheter use for cervical ripening (rate difference 37%, P = 0.007). Currently, all respondent hospitals have an oxytocin protocol; district hospitals had a significant increase in use of post-maturity protocols (rate difference = 40%, P = 0.01) but there was no change in use of prostaglandin protocols.

Inter-hospital variations in labor induction and outcomes for nullipara: an Australian population-based linkage study.

INTRODUCTION: This study aimed to describe variation in inter-hospital induction of labor (IOL) rates, determine whether variation is explained by individual and hospital factors and examine birth outcomes. MATERIAL AND METHODS: Nullipara at term with a singleton cephalic birth were identified using linked hospital discharge and birth data for 66 hospitals in New South Wales, Australia, 2010-2011. Random effects multilevel logistic regression models were fitted for early term, full term, and late term births, adjusting for individual and hospital factors. Hospital intrapartum cesarean rates, and severe maternal and neonatal morbidity outcomes were determined according to hospital IOL rate. RESULTS: Of 69 549 nullipara, 24 673 (35%) had an IOL. For early term births, adjusted hospital IOL (aIOL) rates varied (3.3-13.9%), with 11 of 66 (17%) hospitals having aIOL rates significantly different from the average aIOL rate. For births at full term, the hospital aIOL rates varied (10.6-32.6%), with 29 hospitals (44%) having aIOL rates significantly different from the average aIOL rate. For late term births, the hospital aIOL rates varied (45.1-67.5%), with 11 hospitals (17%) having aIOL rates significantly different from the overall average aIOL rate for women with late term births. There was generally no relationship between higher or lower hospital IOL rates and intrapartum cesarean section rates, or maternal or neonatal adverse outcomes. CONCLUSIONS: Inter-hospital IOL rates for nullipara with a singleton cephalic term birth had high unexplained variation, with no clear association with intrapartum cesarean section rates, or maternal or neonatal adverse outcomes.

Prevalence of noncaesarean uterine surgical scars in a maternity population.

The prevalence of noncaesarean section uterine surgical scars in a general obstetric population was 3.0 of 1000 deliveries and among nulliparae 3.4 of 1000 deliveries, calculated from population data of all delivery records in New South Wales from 2005 to 2011. As the population prevalence is low, women with a noncaesarean section uterine surgical scar are unlikely to impact the analyses of factors associated with caesarean section.

Red blood cell transfusion after postpartum haemorrhage and breastmilk feeding at discharge: A population-based study.

BACKGROUND: Recently released patient blood management guidelines for maternity patients in Australia highlighted the lack of evidence on functional outcomes post-transfusion. AIM: This study aimed to determine the association between red blood cell transfusion and breastmilk feeding at discharge. MATERIALS AND METHODS: Population-based cohort study of all births (n = 522 534) of at least 20 weeks gestation or 400 g birthweight in New South Wales, 2007-2012. Multivariable Poisson regression was used to analyse the association between red cell transfusion post-delivery and breastfeeding at discharge among women experiencing a postpartum haemorrhage (PPH). RESULTS: Overall, 461 395 of 522 534 maternities were breastmilk feeding at discharge, a rate of 88% (82% exclusive; 6% partial). Of 35 588 maternities with a PPH that did not receive a transfusion, 31 387 were breastmilk feeding at discharge (88%; 81% exclusive; 7% partial). There were 4561 maternities with a PPH that were transfused and 3737 were breastmilk feeding at discharge (82%; 70% exclusive; 12% partial). After adjusting for differences in clinical and demographic characteristics, women receiving transfusions are 0.91 (99%CI: 0.89-0.93) times as likely to exclusively breastmilk feed at discharge, compared to nontransfused women. The rate of any breastmilk feeding is 0.94 (99% CI: 0.92-0.95) times lower for transfused women, compared to nontransfused women. CONCLUSIONS: Transfused women have reduced breastmilk feeding rates at discharge. Caution is warranted when advising women that transfusion promotes breastmilk feeding. Additional lactation support may be required for transfused women.

Venous thromboembolism prophylaxis during and following caesarean section: a survey of clinical practice.

BACKGROUND: Caesarean section (CS) is a significant risk factor for venous thromboembolism; however, the optimal method of thromboprophylaxis around the time of CS is unknown. AIMS: To examine current thromboprophylaxis practice during and following CS in Australia and New Zealand, and the willingness of obstetricians to participate in a randomised controlled trial (RCT) comparing different methods of thromboprophylaxis after CS. MATERIALS AND METHODS: An online survey was sent to fellows and trainees of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists. RESULTS: There were 488 responses from currently practising obstetricians (response rate 23.4%). During CS, 48% and 80% of obstetricians recommended intermittent pneumatic compression (IPC) and elastic stockings (ES), respectively. Following CS, 96-97% of obstetricians recommended early ambulation, 87-90% recommended ES, 23-36% recommended IPC, and 42-65% recommended low molecular weight heparin (LMWH) depending on clinical factors. Increased BMI (OR 3.42; 95% CI 2.87-4.06), emergency CS (OR 1.88; 95% CI 1.67-2.16) and older maternal age (OR 1.37; 95% CI 1.26-1.49) were associated with more frequent LMWH use. Of obstetricians who prescribed LMWH, 70% adjusted the dose depending on maternal weight. LMWH therapy was most commonly recommended until discharge from hospital (31%), <5 days (24%) and 5-7 days (15%). Most obstetricians (58-79%) were willing to enrol women in a RCT, but less likely if the woman had an increased BMI or emergency CS. CONCLUSIONS: There is considerable variation in clinical practice regarding thromboprophylaxis during and following CS. Obstetricians support a RCT to assess different methods of thromboprophylaxis following CS.

Variation in hospital caesarean section rates for women with at least one previous caesarean section: a population based cohort study.

BACKGROUND: Internationally, repeat caesarean sections make the largest contribution to overall caesarean section rates and inter-hospital variation has been reported. The aim of this study was to determine if casemix and hospital factors explain variation in hospital rates of repeat caesarean sections and whether these rates are associated with maternal and neonatal morbidity. METHODS: This population-based record linkage study utilised data from New South Wales, Australia between 2007 and 2011. The study population included maternities with any previous caesarean section(s) and were singleton, cephalic and ≥ 37 weeks' gestation (Robson Group 5). Multilevel regression models were used to examine variation in hospital rates of 'planned repeat caesarean section' and, among women who planned a vaginal birth, 'intrapartum caesarean section'. We assessed associations between risk-adjusted hospital rates of planned and intrapartum caesarean sections and rates of casemix adjusted maternal and neonatal morbidity, postpartum haemorrhage and Apgar score <7 at five minutes. RESULTS: Of 61894 maternities with a previous caesarean section in 81 hospitals, 82.1% resulted in a caesarean section (72.7% planned and 9.4% unplanned intrapartum caesareans) and 17.9% in vaginal birth. Observed hospital rates of planned caesarean sections ranged from 50.7% to 98.4%. Overall 49.0% of between-hospital variation in planned repeat caesarean section rates was explained by patient (17.3%) and hospital factors (31.7%). Increased odds of planned caesarean section were associated with private hospital status and lower hospital propensity for vaginal birth after caesarean. There were no associations between hospital rates of planned repeat caesarean section and adjusted morbidity rates. Among women who intended a vaginal birth, the observed rates of intrapartum caesarean section ranged from 12.9% to 71.9%. In total, 27.5% of between-hospital variation in rates of intrapartum caesarean section was explained by patient (19.5%) and hospital factors (8.0%). The adjusted morbidity rates differed among hospital intrapartum caesarean section rates, but were influenced by a few hospitals with outlying morbidity rates. CONCLUSIONS: Among women with at least one previous caesarean section, less than half of the variation in hospital caesarean section rates was explained by differences in hospital's patient characteristics and practices. Strategies aimed at modifying caesarean section rates for these women should not affect morbidity rates.

Prenatal iodine supplementation and early childhood neurodevelopment: the PoppiE trial - study protocol for a multicentre randomised controlled trial.

INTRODUCTION: Observational studies suggest both low and high iodine intakes in pregnancy are associated with poorer neurodevelopmental outcomes in children. This raises concern that current universal iodine supplement recommendations for pregnant women in populations considered to be iodine sufficient may negatively impact child neurodevelopment. We aim to determine the effect of reducing iodine intake from supplements for women who have adequate iodine intake from food on the cognitive development of children at 24 months of age. METHODS AND ANALYSIS: A multicentre, randomised, controlled, clinician, researcher and participant blinded trial with two parallel groups. Using a hybrid decentralised clinical trial model, 754 women (377 per group) less than 13 weeks' gestation with an iodine intake of ≥165 µg/day from food will be randomised to receive either a low iodine (20 µg/day) multivitamin and mineral supplement or an identical supplement containing 200) µg/day (amount commonly used in prenatal supplements in Australia), from enrolment until delivery. The primary outcome is the developmental quotient of infants at 24 months of age assessed with the Cognitive Scale of the Bayley Scales of Infant Development, fourth edition. Secondary outcomes include infant language and motor development; behavioural and emotional development; maternal and infant clinical outcomes and health service utilisation of children. Cognitive scores will be compared between groups using linear regression, with adjustment for location of enrolment and the treatment effect described as a mean difference with 95% CI. ETHICS AND DISSEMINATION: Ethical approval has been granted from the Women's and Children's Health Network Research Ethics Committee (HREC/17/WCHN/187). The results of this trial will be presented at scientific conferences and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT04586348.