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 Mortality in a Rural District of Pakistan and Contributing Factors.

INTRODUCTION: Pakistan is among the ten countries that account for 60% of global maternal mortality. Lack of accurate data on maternal mortality and a complex interrelation of access and quality of healthcare services, healthcare delivery system, and socio-economic and demographic factors contribute significantly to inadequate progress in reducing maternal mortality. MATERIAL AND METHODS: A population-based prospective cohort study was conducted in a rural district of Pakistan using data obtained from an enhanced surveillance system. A total of 7572 pregnancies and their outcomes were recorded by 273 Lady Health Workers and 73 Community Health Workers over 2016-2017. Logistic regression was used to calculate the unadjusted and adjusted odds ratios (OR) for maternal mortality for each risk factor. Population Attributable Fraction (PAF) was derived from the ORs and risk factor prevalence. RESULTS: The study recorded 18 maternal deaths. The maternal mortality rate was estimated at 238/100,000 pregnancies (95% CI 141-376), and the maternal mortality ratio was 247/100,000 live births (95% CI 147-391). Half of the maternal deaths (9) were from obstetric hemorrhage, and 28% (5) from puerperal sepsis. Postpartum hemorrhage was associated with a 17-fold higher risk of maternal mortality (PAF = 40%) and puerperal sepsis with a 12-fold higher mortality risk (PAF = 29%) compared to women without these conditions. Women delivered by unskilled birth attendants had a three-fold (PAF = 21%), and women having prolonged labour had a fourfold risk of maternal mortality compared to those with these conditions. Women with leg swelling (47%) and pre-eclampsia (26%) are at seven times the risk of maternal mortality compared to those without these conditions. Mortality in women delivered by unskilled birth attendants was three times higher than with skilled attendants. CONCLUSION: The study, among a few large-scale prospective cohort studies conducted at the community level in a rural district of Pakistan, provides a better understanding of the risk factors determining maternal mortality in Pakistan. Poverty emerged as a significant risk factor for maternal mortality in the study area and contributes to the underutilization of health facilities and skilled birth attendants. Incorporating poverty reduction strategies across all sectors, including health, is urgently required to address higher maternal mortality in Pakistan. A paradigm shift is required in Maternal and Child health related programs and interventions to include poverty estimation and measuring mortality through linking mortality surveillance with the Civil Registration and Vital Statistics system. Accelerated efforts to expand the coverage and completeness of mortality data with risk factors to address inequalities in access and utilization of health services.

Interventional radiology in obstetric patients: A population-based record linkage study of use and outcomes.

INTRODUCTION: Interventional radiology (IR) is a technique for controlling hemorrhage and preserving fertility for women with serious obstetric conditions such as placenta accreta spectrum (PAS) or postpartum hemorrhage. This study examined maternal, pregnancy and hospital characteristics and outcomes for women receiving IR in pregnancy and postpartum. MATERIAL AND METHODS: A population-based record linkage study was conducted, including all women who gave birth in hospital in New South Wales or the major tertiary hospital in the neighboring Australian Capital Territory, Australia, between 2003 and 2019. Data were obtained from birth and hospital records. Characteristics and outcomes of women who underwent IR in pregnancy or postpartum are described. Outcomes following IR were compared in a high-risk cohort of women: those with PAS who had a planned cesarean with hysterectomy. Women were grouped by those who did and those who did did not have IR and were matched using propensity score and other factors. RESULTS: We identified IR in 236 pregnancies of 1 584 708 (15.0 per 100 000), including 208 in the delivery and 26 in a postpartum admission. Two-thirds of women receiving IR in the birth admission received a transfusion of red cells or blood products, 28% underwent hysterectomy and 12.5% were readmitted within 6 weeks. Other complications included: severe maternal morbidity (29.8%), genitourinary tract trauma/repair (17.3%) and deep vein thrombosis/pulmonary embolism (4.3%). Outcomes for women with PAS who underwent planned cesarean with hysterectomy were similar for those who did and did not receive IR, with a small reduction in transfusion requirement for those who received IR. CONCLUSIONS: Interventional radiology is infrequently used in pregnant women. In our study it was performed at a limited number of hospitals, largely tertiary centers, with the level of adverse outcomes reflecting use in a high-risk population. For women with PAS undergoing planned cesarean with hysterectomy, most outcomes were similar for those receiving IR and those not receiving IR, but IR may reduce bleeding.

Pregnancy outcomes in women with endometriosis and/or ART use: a population-based cohort study.

STUDY QUESTION: What is the association between endometriosis and adverse pregnancy outcomes with ART use and non-use? SUMMARY ANSWER: Endometriosis and ART use are both associated with increased risk of preterm birth, antepartum haemorrhage, placenta praevia and planned birth (caesarean delivery or induction of labour). WHAT IS KNOWN ALREADY: There are contradictory findings on the association between endometriosis and adverse pregnancy outcomes, and many large studies have not considered the effect of ART use. STUDY DESIGN, SIZE, DURATION: Population-based cohort study of 578 221 eligible pregnancies during 2006-2015, comparing pregnancy outcomes across four groups (No endo/no ART, No endo/ART, Endo/no ART and Endo/ART). PARTICIPANTS/MATERIALS, SETTING, METHODS: All female residents of New South Wales, Australia aged 15-45 years and their index singleton pregnancy of at least 20 weeks gestation or 400 g birthweight. Linked hospital, pregnancy/birth and mortality data were used. Modified Poisson regression with robust error variances was used to estimate adjusted risk ratios (aRRs) and 99% CIs, adjusting for sociodemographic and pregnancy factors. MAIN RESULTS AND THE ROLE OF CHANCE: Compared to women without endometriosis who had pregnancies without ART use, there was increased risk of preterm birth (<37 weeks) in all groups [No endo/ART (aRR 1.85, 99% CI 1.46-2.34), Endo/no ART (aRR 1.24, 99% CI 1.06-1.44), Endo/ART (aRR 1.93, 99% CI 1.11-3.35)] and antepartum haemorrhage [No endo/ART (aRR 1.99, 99% CI 1.39-2.85), Endo/no ART (aRR 1.31, 99% CI 1.03-1.67), Endo/ART (aRR 2.69, 99% CI 1.30-5.56)] among pregnancies affected by endometriosis or ART use, separately and together. There was increased risk of placenta praevia [No endo/ART (aRR 2.26, 99% CI 1.42-3.60), Endo/no ART (aRR 1.66, 99% CI 1.18-2.33)] and planned birth [No endo/ART (aRR 1.08, 99% CI 1.03-1.14), Endo/no ART (aRR 1.11, 99% CI 1.07-1.14)] among pregnancies with endometriosis or ART use, separately. There was increased risk of placental abruption [No endo/ART (aRR 2.36, 99% CI 1.12-4.98)], maternal morbidity [No endo/ART (aRR 1.67, 99% CI 1.07-2.62)] and low birthweight (<2500 g) [No endo/ART (aRR 1.45, 99% CI 1.09-1.93)] among pregnancies with ART use without endometriosis. There was decreased risk of having a large-for-gestational age infant [Endo/no ART (aRR 0.83, 99% CI 0.73-0.94)] among pregnancies with endometriosis without ART use. LIMITATIONS, REASONS FOR CAUTION: Endometriosis is often under-diagnosed and women with a history of hospital diagnosis of endometriosis may represent those with more symptomatic or severe disease. If the effects of endometriosis on pregnancy are greater for those with more severe disease, our results may over-estimate the effect of endometriosis on adverse pregnancy outcomes at a population level. We were unable to assess the effect of endometriosis stage or typology on the study outcomes. WIDER IMPLICATIONS OF THE FINDINGS: These results suggest that women with endometriosis including those who used ART to achieve pregnancy are a higher-risk obstetric group requiring appropriate surveillance and management during their pregnancy. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by the Prevention Research Support Program, funded by the New South Wales Ministry of Health. The funder had no role in the design, data collection and analysis, interpretation of results, manuscript preparation or the decision to submit the manuscript for publication. The authors have no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

Alternatives to low birthweight as a population-level indicator of infant and child health.

BACKGROUND: Low birthweight (<2500 g) is often used as a population-level indicator of maternal-child health, as it is easy to measure and correlates with poorer infant health outcomes. However, it conflates preterm birth and intrauterine growth restriction, which have different causal pathways and require different approaches to prevention. Small for gestational age (SGA) (a proxy for growth restriction) and preterm birth may be more informative measures. We evaluated low birthweight as a population-level indicator. METHODS: We conducted a population-based cohort study of singleton live births in New South Wales (NSW), Australia, using linked data from 1994-2006 birth, hospital, death and educational records, with follow-up until 2014. Outcomes of babies born of low birthweight, preterm and SGA were compared with well-grown term infants (i.e. not low birthweight or SGA). Overlap between groups and temporal trends were also examined. RESULTS: Of 1 093 765 singleton live births, 47 946 (4.4%) infants were low birthweight and had poorer outcomes than well-grown term infants (2.7% vs. 0.1% infant mortality; 13% vs. 6% below national minimum numeracy standard). SGA and preterm infants also had poorer outcomes (0.5%, 2.3% infant mortality respectively; 10%, 11% below numeracy standard) but 80% of SGA and 47% of preterm infants were not low birthweight. For all outcomes, low birthweight identified a smaller proportion of infants with poor outcomes than preterm birth and than either SGA or low birthweight at term. The proportion of low-birthweight births remained constant over time, while the proportion of births that were preterm increased and proportion of SGA decreased. CONCLUSIONS: Low birthweight, SGA and preterm infants are all at higher risk of poorer outcomes but low birthweight inadequately captures, and masks trends in, both preterm births and births that are SGA. Reporting preterm births and an indicator of growth restriction at term will identify vulnerable groups better than using the measure of low birthweight.

Benefits of not smoking during pregnancy for non-Aboriginal women and their babies in New South Wales, Australia: a record linkage study.

BACKGROUND: Smoking rates among pregnant women in New South Wales (NSW) have plateaued at 8-9%. To inform relevant smoking reduction efforts, we aimed to quantify the benefits of not smoking during pregnancy for non-Aboriginal NSW mothers and their babies. The benefits of not smoking during pregnancy for NSW Aboriginal mothers have previously been described. These data are important inputs in modelling health and economic impacts of smoking cessation interventions. METHODS: This population-based cohort study used linked-data from routinely collected data sets. Not smoking during pregnancy was the exposure of interest among all NSW non-Aboriginal women who became mothers of singleton babies in 2012-2016. Unadjusted and adjusted relative risks (aRR) were used to examine associations between not smoking during pregnancy and adverse outcomes including severe morbidity, inter-hospital transfer, perinatal death, preterm birth and small-for-gestational age. Population attributable fractions (PAFs) were calculated to quantify adverse perinatal outcomes avoided in the population if all mothers were non-smokers. RESULTS: Compared with babies born to mothers who smoked during pregnancy, babies born to non-smoking mothers had a lower risk of all adverse perinatal outcomes including perinatal death (aRR = 0.68, 95%CI 0.61-0.76), preterm birth (aRR = 0.58, 95%CI 0.56-0.61) and small-for-gestational age (aRR = 0.48, 95%CI 0.47-0.50). PAFs(%) were 3.9% for perinatal death, 5.6% for preterm birth and 7.3% for small-for-gestational-age. Compared with women who smoked during pregnancy (n = 36,518), those who did not smoke (n = 413,072) had a lower risk of suffering severe maternal morbidity (aRR = 0.87, 95%CI 0.81-0.93) and being transferred to another hospital (aRR = 0.92, 95%CI 0.86-0.99). CONCLUSIONS: Mothers who reported not smoking during pregnancy had a small reduction in their risk of morbidity and of being transferred to another hospital whilst their babies had substantially reduced risks of all adverse perinatal outcomes. Results have implications for clinician training, clinical care standards, and performance management.

Place of birth and outcomes associated with large volume transfusion: an observational study.

BACKGROUND: Guidelines recommend that women at high risk of postpartum haemorrhage deliver at facilities able to handle heavy bleeding. However postpartum haemorrhage is often unexpected. This study aims to compare outcomes and health service use related to transfusion of ≥4 units of red blood cells between women delivering in tertiary and lower level hospitals. METHODS: The study population was women giving birth in public hospitals in New South Wales, Australia, between July 2006 and December 2010. Data were obtained from linked hospital, birth and blood bank databases. The exposure of interest was transfusion of four or more units of red cells during admission for delivery. Outcomes included maternal morbidity, length of stay, neonatal morbidity and need for other blood products or transfer to higher care. Multivariable regression models were developed to predict need of transfusion of ≥4 units of red cells using variables known early in pregnancy and those known by the birth admission. RESULTS: Data were available for 231,603 births, of which 4309 involved a blood transfusion, with 1011 (0.4%) receiving 4 or more units. Women giving birth in lower level and/or smaller hospitals were more likely to receive ≥4 units of red cells. Women receiving ≥4 units in tertiary settings were more likely to receive other blood products and have longer hospital stays, but morbidity, readmission and hysterectomy rates were similar. Although 46% of women had no identifiable risk factors early in pregnancy, 20% of transfusions of ≥4 units occurred within this group. By the birth admission 70% of women had at least one risk factor for requiring ≥4 units of red cells. CONCLUSIONS: Overall outcomes for women receiving ≥4 units of red cells were comparable between tertiary and non-tertiary facilities. This is important given the inability of known risk factors to predict many instances of postpartum haemorrhage.

Comparison of costs related to infant hospitalisations for spontaneous, induced and Caesarean births: population-based cohort study.

Objective This study examined hospitalisations and associated in-patient costs for babies during the first year of life following spontaneous labour, compared with labour induction or prelabour Caesarean section, at each gestational age. Methods Birth data for singleton liveborn babies from 33 weeks gestation in New South Wales from 2005 to 2014 were linked to hospital and death data. Generalised linear models were used to examine the association between the type of labour and the length of hospitalisations and hospital costs. Results From 2005 to 2014, 598640 women gave birth to 1187451 liveborn singleton babies. The mean total length of hospitalisations and costs of hospitalisations for babies in the first year of life decreased significantly as week of gestational age increased to 39 weeks, then plateaued. Overall, the total length of hospitalisations and hospital costs were significantly (P<0.001) lower for babies born after spontaneous labour (5.6 days and A$8405 respectively) than for babies born following labour induction (6.1 days and A$9452 respectively) or prelabour Caesarean section (8.2 days and A$12320 respectively). Conclusions Babies born following spontaneous labour spend less time in hospital and have lower hospital costs than those born following labour induction or prelabour Caesarean section. Hospitalisations and costs decrease with each week of gestational age until 39 weeks. What is known about the topic? It is known that induction of labour and prelabour Caesarean sections are increasing, and this increase has changed the distribution of gestational age towards birth at earlier ages. It is also known that babies born before 39 weeks of gestation are at increased risk of mortality and morbidity. What does this paper add? This study shows that babies born following spontaneous labour spend the least amount of time in hospital and subsequently have the lowest hospital costs at each week of gestation compared with babies born following labour induction or prelabour Caesarean section. This study also shows a small but significant economic advantage of labour induction compared with prelabour Caesarean delivery. This study quantifies the mean time babies spend in hospital in their first year of life, by week of gestational age and mode of birth. What are the implications for practitioners? The findings from this study can assist clinicians in judicious decision making when balancing the risks and benefits of early planned births. Clinicians can use the results of this study to inform women who are intending to have a planned birth of risks they may not have anticipated, such as the increased risk of rehospitalisation. The finding that hospitalisations and costs continue to decline until 39 weeks gestation can be used to reinforce the importance of continuing the pregnancy beyond 37 weeks if safe to do so, even though 37 weeks is considered term.

Validation of anaemia, haemorrhage and blood disorder reporting in hospital data in New South Wales, Australia.

OBJECTIVE: Hospital data are a useful resource for studying pregnancy complications, including bleeding-related conditions, however, the reliability of these data is unclear. This study aims to examine reliability of reporting of bleeding-related conditions, including anaemia, obstetric haemorrhage and blood disorders, and procedures, such as blood transfusion and hysterectomy, in coded hospital records compared with obstetric data from two large tertiary hospitals in New South Wales. RESULTS: There were 36,051 births between 2011 and 2015 included in the analysis. Anaemia and blood disorders were poorly reported in the hospital data, with sensitivity ranging from 2.5% to 24.8% (positive predictive value (PPV) 12.0-82.6%). Reporting of postpartum haemorrhage, transfusion and hysterectomy showed high sensitivity (82.8-96.0%, PPV 78.0-89.6%) while moderate consistency with the obstetric data was observed for other types of obstetric haemorrhage (sensitivity: 41.9-65.1%, PPV: 50.0-56.8%) and placental complications (sensitivity: 68.2-81.3%, PPV: 20.3-72.3%). Our findings suggest that hospital data may be a reliable source of information on postpartum haemorrhage, transfusion and hysterectomy. However, they highlight the need for caution for studies of anaemia and blood disorders, given high rates of uncoded and 'false' cases, and suggest that other sources of data should be sought where possible.

Reporting of gestational diabetes and other maternal medical conditions: validation of routinely collected hospital data from New South Wales, Australia.

INTRODUCTION: Hospital datasets are a valuable resource for examining prevalence and outcomes of medical conditions during pregnancy. To enable effective research and health planning, it is important to determine whether variables are reliably captured. OBJECTIVE: To examine the reliability of reporting of gestational and pre-existing diabetes, hypertension, thyroid conditions, and morbid obesity in coded hospital records that inform the population-level New South Wales Admitted Patient Data Collection. METHODS: Coded hospital admission data from two large tertiary hospitals in New South Wales, from 2011 to 2015, were compared with obstetric data, collected by midwives at outpatient pregnancy booking and in hospital after birth, as the reference standard. Records were deterministically linked and sensitivity, specificity, positive predictive values and negative predictive values for the conditions of interest were obtained. RESULTS: There were 36,051 births included in the analysis. Sensitivity was high for gestational diabetes (83.6%, 95% CI 82.4-84.7%), pre-existing diabetes (88.2%, 95% CI 84.1-91.6%), and gestational hypertension (80.1%, 95% CI 78.2-81.9%), moderate for chronic hypertension (53.5%, 95% CI 47.8-59.1%), and low for thyroid conditions (12.9%, 95% CI 11.7-14.2%) and morbid obesity (9.8%, 95% CI 7.6-12.4%). Specificity was high for all conditions (≥97.8%, 95% CI 97.7-98.0) and positive predictive value ranged from 53.2% for chronic hypertension (95% CI 47.5-58.8%) to 92.7% for gestational diabetes (95% CI 91.8-93.5%). CONCLUSION: Our findings suggest that coded hospital data are a reliable source of information for gestational and pre-existing diabetes and gestational hypertension. Chronic hypertension is less consistently reported, which may be remedied by grouping hypertension types. Data on thyroid conditions and morbid obesity should be used with caution, and if possible, other sources of data for those conditions should be sought.

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.

Is mode of first birth a risk factor for subsequent preterm birth?

BACKGROUND: Previous preterm birth is a strong predictor of subsequent preterm birth, but less is known about the causes of preterm birth following a full-term first pregnancy. Recent research has highlighted previous caesarean section as a potential risk factor. AIM: To examine the relationship between mode of first birth and the risk of subsequent preterm birth in New South Wales (NSW), Australia. MATERIALS AND METHODS: A population-based record-linkage study of NSW women who had a live singleton first birth at ≥37 weeks gestation, followed by a singleton second birth between 2005 and 2017. Relative risk (RR) and 95% CI of preterm birth in the subsequent pregnancy was calculated using modified Poisson regression, with mode of first birth as the exposure. Spontaneous preterm birth and preterm prelabour caesarean were secondary outcomes. RESULTS: Women who had either an intrapartum (RR: 1.26, 95% CI 1.19-1.32) or prelabour caesarean (RR: 1.26, 95% CI 1.18-1.35) first birth had a higher risk of subsequent preterm birth (any birth <37 weeks gestation), than those who birthed vaginally. Women who had a previous instrumental birth (RR: 0.85, 95% CI 0.79-0.91) or prelabour caesarean (RR: 0.74, 95% CI 0.67-0.82) had lower risks of subsequent spontaneous preterm birth. However, prior prelabour caesarean also greatly increased risk of subsequent preterm prelabour caesarean (RR: 5.25, 95% CI 4.65-5.93). CONCLUSIONS: The mode of first birth has differing effects on the risk of subsequent spontaneous preterm birth and preterm prelabour caesarean. Awareness of the risk of subsequent preterm birth following caesarean section may help inform clinical decisions around mode of first birth.

Pregnancy outcomes for women with a history of stroke: A population-based record linkage study.

BACKGROUND: Little is known about the pregnancy outcomes of women who have had a stroke prior to a first pregnancy. AIM: To identify a cohort of primiparous women giving birth to a single baby and compare the pregnancy outcomes of those with a pre-pregnancy stroke hospitalisation record to those without a stroke hospitalisation record. MATERIALS AND METHODS: Record linkage study of all primiparous women aged 15-44 years with singleton pregnancies birthing in New South Wales, Australia from 2003 to 2015. Stroke was identified from 2001 to 2015 hospital data using International Classification of Diseases tenth Edition - Australian Modification codes I60-64. Women whose first hospital record of stroke was during pregnancy or <42 days after birth were excluded. Outcomes included diabetes or hypertension during pregnancy, mode of delivery, haemorrhage, severe maternal morbidity (validated composite outcome indicator), gestational age at birth, Apgar score (1 min < 7), and small-for-gestational age. RESULTS: Of 487 767 women with a first pregnancy, 124 (2.5/10 000) had a hospital record which included a pre-pregnancy stroke diagnosis. Women with a stroke history were more likely to have an early-term delivery (37-38 weeks; relative risk (RR) 1.49, 95% CI 1.17-1.90) and a pre-labour caesarean (RR 2.83, 95% CI 2.20-3.63). There were no significant differences in other maternal or neonatal outcomes. CONCLUSION: This is the largest reported study of pregnancy and birth outcomes for women with a history of stroke. With the exception of pre-labour caesarean, there were no differences in pregnancy outcomes for women with a history of stroke compared with women with no history of stroke.

Global production capacity of seasonal and pandemic influenza vaccines in 2019.

Vaccines will be an important element in mitigating the impact of an influenza pandemic. While research towards developing universal influenza vaccines is ongoing, the current strategy for vaccine supply in a pandemic relies on seasonal influenza vaccine production to be switched over to pandemic vaccines. Understanding how much vaccine could be produced, in which regions of the world and in what timeframe is critical to informing influenza pandemic preparedness. Through the Global Action Plan for Influenza Vaccines, 2006-2016, WHO promoted an increase in vaccine production capacity and monitors the landscape through periodically surveying influenza vaccine manufacturers. This study compares global capacity for production of influenza vaccines in 2019 with estimates from previous surveys; provides an overview of countries with established production facilities; presents vaccine production by type and manufacturing process; and discusses limitations to these estimates. Results of the current survey show that estimated annual seasonal influenza vaccine production capacity changed little since 2015 increasing from 1.47 billion to 1.48 billion doses with potential maximum annual influenza pandemic vaccine production capacity increasing from 6.37 billion to 8.31 billion doses. However, this figure should be interpreted with caution as it presents a best-case scenario with several assumptions which may impact supply. Further, pandemic vaccines would not be immediately available and could take four to six months for first supplies with several more months needed to reach maximum capacity. A moderate-case scenario is also presented of 4.15 billion doses of pandemic vaccine in 12 months. It is important to note that two doses of pandemic vaccine are likely to be required to elicit an adequate immune response. Continued efforts are needed to ensure the sustainability of this production and to conduct research for vaccines that are faster to produce and more broadly protective taking into account lessons learned from COVID-19 vaccine development.

Outcomes of Subsequent Births After Placenta Accreta Spectrum.

OBJECTIVE: To investigate subsequent birth rates, maternal and neonatal outcomes for women with a history of placenta accreta spectrum (placenta accreta, increta, and percreta). METHODS: A population-based record linkage study of women who had a first, second, or third birth in New South Wales from 2003 to 2016 was conducted. Data were obtained from birth and hospital records and death registrations. Women with a history of placenta accreta spectrum were matched to women without, on propensity score and parity, to compare outcomes with women who had similar risk profiles. Modified Poisson regression models were used to calculate adjusted relative risk (aRR) for a range of maternal and neonatal outcomes. RESULTS: We identified recurrent placenta accreta spectrum in 27/570 (4.7%, 95% CI 3.0-6.5%) of second and 9/119 (7.6%, 95% CI 2.8-12.3%) of third pregnancies after placenta accreta spectrum in the preceding birth, with an overall recurrence rate of 38/689 (5.5%, 95% CI 3.9-7.5%, compared with the population prevalence of 25.5/10,000 births (95% CI 24.6-26.4). Subsequent births after placenta accreta spectrum had higher risk of postpartum hemorrhage (aRR 1.51, 95% CI 1.19-1.92), transfusion (aRR 2.13, 95% CI 1.17-3.90), cesarean delivery (aRR 1.19, 95% CI 1.02-1.37), manual removal of placenta (aRR 6.92, 95% CI 3.81-12.55), and preterm birth (aRR 1.43, 95% CI 1.03-1.98), with lower risk of small for gestational age (aRR 0.64, 95% CI 0.43-0.96), compared with similar-risk births. CONCLUSION: Women with a history of placenta accreta spectrum have increased risk of maternal morbidity, preterm birth, and placenta accreta spectrum in the subsequent pregnancy compared with similar-risk women with no previous placenta accreta spectrum, although the absolute risks are generally low. These findings may be used to inform counseling of women on the risks of future pregnancies.

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.

Rates of stillbirth by maternal region of birth and gestational age in New South Wales, Australia 2004-2015.

BACKGROUND: Research suggests that in Australia, maternal region of birth is a risk factor for stillbirth. AIMS: We aimed to examine the relationship between stillbirth and maternal region of birth in New South Wales (NSW), Australia from 2004 to 2015. METHODS: Adjusted logistic regression was used to determine odds of stillbirth by maternal region of birth, compared with Australian or New Zealand-born (AUS/NZ-born) women. Intervention rates (induction or pre-labour caesarean) by maternal region of birth, over time, were also examined. Interaction terms were used to assess change in relative odds of stillbirth, over two time periods (2004-2011 and 2012-2015). RESULTS: There were 944 457 singleton births ≥24 weeks gestation that met the study inclusion criteria and 3221 of these were stillbirths, giving a stillbirth rate of 3.4 per 1000 births. After adjustment for confounders, South Asian (adjusted odds ratio (aOR) 1.42, 95% CI 1.24-1.62), Oceanian (aOR 1.45, 95% CI 1.17-1.80) and African (aOR 1.46, 96% CI 1.19-1.80) born women had significantly higher odds of stillbirth that AUS/NZ-born women. Intervention rates increased from the earlier to the later time period by 13.1% across the study population, but the increase was larger in African and South Asian-born women (18.1% and 19.6% respectively) than AUS/NZ-born women (11.2%). There was a significant interaction between ethnicity and time period for South Asian-born women in the all-births model, with their stillbirth rates becoming closer to AUS/NZ-born women in the later period. CONCLUSION: South Asian, African and Oceanian maternal region of birth are independent risk factors for stillbirth in NSW.

Gestational age, morbidity and mortality among twin births in New South Wales, Australia 2003-2014: A cohort study.

BACKGROUND: Evidence suggests that the trend toward early planned births observed among singletons may be evident among twin pregnancies. AIMS: To describe trends in gestational age at birth, pregnancy characteristics, neonatal morbidity and mortality among twin pregnancies. MATERIALS AND METHODS: Population-based data linkage study of twin births of ≥30 weeks of gestation without a major congenital anomaly born in 2003-2014 in New South Wales (NSW), Australia. Linked pregnancy and birth, hospital and mortality data were used. Generalised linear regression was used to assess linear trends. Risk difference (RD) and 95% confidence intervals were estimated. RESULTS: Among 28 076 eligible twin births (14 038 pregnancies), 49% of births occurred prior to 37 weeks and 69% of births were planned (pre-labour caesarean or induction of labour). There were increases over time in the proportion of twin births at preterm gestations (30-34 weeks (RD 2.1, 95% CI 0.1, 4.0), 35-36 weeks (RD 7.5, 95% CI 5.4, 9.7)) and in the rates of planned births (pre-labour caesarean (RD 6.4, 95% CI 4.0, 8.8), induction (RD 4.6, 95% CI 2.6, 6.6)). There was no significant change in stillbirth or neonatal death rates, but there was an increase in neonatal morbidity over the study period. Concurrently, there were increases in the prevalence of gestational diabetes; and decreases in pregnancy hypertension, assisted reproductive technology use, small-for-gestational age and birthweight discordance. CONCLUSIONS: Gestational age at birth among twin births is decreasing and birth intervention is increasing. There are increasing rates of neonatal morbidity, but no overall change in perinatal mortality.

Benefits of not smoking during pregnancy for Australian Aboriginal and Torres Strait Islander women and their babies: a retrospective cohort study using linked data.

OBJECTIVES: To provide evidence for targeted smoking cessation policy, the aim of this study was to compare pregnancy outcomes of Aboriginal mothers who reported not smoking during pregnancy with Aboriginal mothers who reported smoking during pregnancy. DESIGN: Population based retrospective cohort study using linked data. SETTING: New South Wales, the most populous Australian state. POPULATION: 18 154 singleton babies born to 13 477 Aboriginal mothers between 2010 and 2014 were identified from routinely collected New South Wales datasets. Aboriginality was determined from birth records and from four linked datasets through an Enhanced Reporting of Aboriginality algorithm. EXPOSURE: Not smoking at any time during pregnancy. MAIN OUTCOME MEASURES: Unadjusted and adjusted relative risks (aRR) and 95% CIs from modified Poisson regression were used to examine associations between not smoking during pregnancy and maternal and perinatal outcomes including severe morbidity, inter-hospital transfer, perinatal death, preterm birth and small-for-gestational age. Population attributable fractions (PAFs) were calculated using adjusted relative risks. RESULTS: Compared with babies born to mothers who smoked during pregnancy, babies born to non-smoking mothers had a lower risk of all adverse perinatal outcomes including perinatal death (aRR=0.58, 95% CI 0.44 to 0.76), preterm birth (aRR=0.58, 95% CI 0.53 to 0.64) and small-for-gestational age (aRR=0.35, 95% CI 0.32 to 0.39). PAFs (%) were 27% for perinatal death, 26% for preterm birth and 48% for small-for-gestational-age. Compared with women who smoked during pregnancy (n=8919), those who did not smoke (n=9235) had a lower risk of being transferred to another hospital (aRR=0.76, 95% CI 0.66 to 0.89). CONCLUSIONS: Babies born to women who did not smoke during pregnancy had a lower risk of adverse perinatal outcomes. Rates of adverse outcomes among Aboriginal non-smokers were similar to those among the general population. These results quantify the proportion of adverse perinatal outcomes due to smoking and highlight why effective smoking cessation programme are urgently required for this population.