Mortality, rehospitalizations and costs in children undergoing a cardiac procedure in their first year of life in New South Wales, Australia.

BACKGROUND: Cardiac procedures are part of management for many children with congenital heart disease (CHD). Using population health data, this study explores health outcomes of children undergoing a cardiac procedure in the first year of life to better understand the impact of CHD on children, families and health services. METHODS AND RESULTS: A population-based record-linkage cohort study was undertaken. Rate of cardiac procedures in the first year of life over the study period 2001-2012 in New South Wales, Australia, was steady at 2.5 children per 1000 live births, accounting for 2722 children. Excluding those with isolated closure of patent ductus arteriosus (n=416), 50% required readmission in the first year of life. Over 1/5th had an additional non-cardiac congenital anomaly. Average total cost per infant for initial procedure admission was $67,054 AUD ($63,124-$70,984) with a median length of stay (LOS) 13days (IQR 8-23). Average cost per readmission in the first year of life was $11,342 (95% CI 10,361-$12,323) with median LOS 2days (IQR 1-5). Mortality rate in the 30days following initial procedure was 3.1% (72/2306). Mortality rate by age 1year was 7.1%, and 13.8% for those who had neonatal surgery. CONCLUSION: Risk of mortality in operatively-managed CHD extends beyond the immediate perioperative period. Children undergoing a cardiac procedure in their first year are often readmitted to hospital for both further planned procedures and unplanned reasons such as infection. These readmissions capture the significant impact of illness and pose substantial financial cost to the health system.

Exploring pneumonia risk factors in Vietnamese infants: a survey of new mothers.

OBJECTIVE: To understand the prevalence of pneumonia risk factors and perceived barriers to risk factor reduction among Vietnamese infants. METHODS: We conducted a cross-sectional survey of mothers in the postnatal wards of Da Nang Hospital for Women and Children in central Vietnam from 10 February 2017 to 24 February 2017. RESULTS: Of 286 mothers surveyed, 259 (91%) initiated breast feeding and 207 (72%) intended to continue exclusive breast feeding for 6 months. No mother smoked cigarettes, but 42% of fathers did. Mothers' decision not to smoke was motivated by concerns for their own health and that of their baby. Households rarely used wood or coal for cooking (6%). Mothers indicated near universal (99%) uptake of the National Expanded Program of Immunization vaccinations. Few (64; 22%) mothers knew about the pneumococcal conjugate vaccine; 56/64 (88%) indicated that they would purchase it for their infants. Family members rarely influenced mothers' decisions about breast feeding or vaccination, except in two instances where fathers were concerned about vaccine-related adverse effects. CONCLUSION: Modifiable pneumonia risk factors were uncommon among newborn babies in central Vietnam, apart from paternal cigarette smoke exposure. Successful local implementation of the WHO Essential Newborn Care package as well as high levels of maternal education and decision autonomy was observed.

Contribution of changing risk factors to the trend in breech presentation at term.

BACKGROUND: Recent population-wide changes in perinatal risk factors may affect rates of breech presentation at birth, and have implications for the provision of breech services and training in breech management. AIMS: To investigate whether changes in maternal and pregnancy characteristics explain the observed trend in breech presentation at term. MATERIALS AND METHODS: All singleton term (≥37 week) births in New South Wales during 2002-2012 were identified through birth and associated hospital records. Annual rates of breech presentation were determined. Logistic regression modelling was used to predict expected rates of breech presentation and these were compared with observed rates over time. A priori predictors included maternal age, country of birth, parity, smoking during pregnancy, diabetes, pregnancy hypertension, placenta praevia, previous singleton term breech, previous caesarean section, infant sex, gestational age, birthweight and congenital anomalies. Hospital and Medicare data were used to assess concomitant trends in external cephalic version. RESULTS: Among 914 147 singleton term births, 3.1% were breech at delivery. Rates of breech presentation declined from 3.6% in 2002 to 2.7% in 2012 (test for trend P < 0.001), but was predicted to increase from 3.6% in 2002 to 4.3% in 2012 because of increased maternal age, nulliparity, maternal diabetes, history of breech presentation and previous caesarean section. However, use of external cephalic version appears to have increased over time. CONCLUSIONS: Breech presentation at delivery has decreased in New South Wales. Increased use of external cephalic version likely accounts for this decline, as changes in risk factors do not.

Vulvoplasty in New South Wales, 2001-2013: a population-based record linkage study.

OBJECTIVES: To compare the characteristics of women who have undergone vulvoplasty with those of other women of reproductive age; to quantify short term adverse events and complications; to determine any association between vulvoplasty and subsequent outcomes for women giving birth. DESIGN, SETTING AND PARTICIPANTS: A population-based record linkage study, analysing New South Wales Admitted Patient Data Collection and NSW Perinatal Data Collection data. The characteristics of all women who had vulvoplasties in NSW hospitals during 2001-2013 were compared with those of all women of reproductive age. MAIN OUTCOME MEASURES: Admissions for vulvoplasty and repeat vulvoplasties; serious complications or adverse events after vulvoplasty; birth mode and perineal outcomes for primiparous women with and without vulvoplasty. RESULTS: 4592 vulvoplasty procedures were performed on 4381 women in NSW hospitals and day-stay centres; the annual rate increased by 64.5% between 2001 and 2013. Compared with the reference population, women who had vulvoplasty were more likely to have been born in Australia (74.6% v 67.6%), to have other cosmetic surgery (10.1% v 1.7%), and to have never been married (43.0% v 33.1%). The serious short term adverse event rate was 7.2%. Of 257 women who had a first birth after their vulvoplasty procedure, 40.0% had caesarean deliveries, compared with 30.3% of other women (P < 0.001). There were no significant differences in the rates of perineal outcomes for women who had vaginal births. CONCLUSIONS: The number of vulvoplasties performed in NSW has increased dramatically since 2001. The procedure is not without serious complications that can necessitate re-admission to hospital. We provide objective information about outcomes for counselling women who are contemplating vulvoplasty.

Variation in and factors associated with timing of low risk, pre-labour repeat caesarean sections in NSW, 2008-2011.

OBJECTIVE: To explore variation in public hospital rates of early (37-38 weeks gestation) prelabour repeat caesarean section among low-risk women at and beyond term in New South Wales (NSW) between 2008 and 2011. IMPORTANCE OF THE STUDY: A NSW Ministry of Health policy directive for public hospitals (PD2007_024), 'Maternity - timing of elective or pre-labour caesarean section', requires that low-risk elective or prelabour caesarean section does not occur before 39 completed weeks gestation. However, compliance with this policy has not been evaluated. STUDY TYPE: Population-based record linkage study Methods: Linked birth and hospital data for low-risk, prelabour repeat caesarean sections in NSW in 2008-2011 were analysed using multilevel regression modelling. Rates were adjusted for casemix and hospital factors. Low-risk pregnancies were defined as singleton live births at 37-42 weeks gestation among women without medical or obstetric complications and where the indication for caesarean section was 'elective repeat caesarean section'. RESULTS: In 2008-2011, there were 15 163 prelabour repeat caesarean sections among low-risk women in NSW. Overall, 34.7% of low-risk prelabour repeat caesarean sections occurred before 39 weeks gestation. Adjusted NSW public hospital rates of early (37-38 weeks gestation) low-risk prelabour repeat caesarean section varied widely (16.3-67.5%). Adjusting for casemix factors actually increased the between-hospital variation by 4.3%; adjusting for hospital factors reduced variation by 20.0%. Smoking, private healthcare, assisted reproductive technology use, higher parity, a noncaesarean uterine scar and delivering in a hospital with CPAP (continuous positive airway pressure) facilities were associated with higher odds of early delivery, although infants that were small for gestational age were associated with lower odds. Hospitals with higher rates of low-risk deliveries and higher propensity for vaginal birth after caesarean section had lower odds of early delivery. CONCLUSIONS: The findings suggest generally poor compliance with the policy directive that prelabour caesarean does not occur before 39 weeks gestation, with adjusted compliance rates ranging from 32.5% to 83.7%. Large between-hospital variation after adjustment suggests that nonmedical factors are related to timing of low-risk prelabour repeat caesarean sections. Further strategies are needed to improve adherence to this evidence based policy.

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.

Interaction of maternal smoking and preterm birth on future risk of maternal cardiovascular disease: A population-based record linkage study.

BACKGROUND: While associations of smoking and preterm birth (PTB) with maternal cardiovascular disease (CVD) risks have been established, it is unknown whether the coexistence of these two conditions could synergistically increase the risks. METHODS: We linked birth records of 902,008 mothers with singleton infants during 1994-2011 in New South Wales, Australia to the mothers' subsequent CVD hospitalisation or death. Multiplicative interaction was tested through an interaction term in a multivariate Cox-proportional hazard regression model, while additive interaction was assessed by calculating the synergy index. RESULTS: Relative to never-smokers with term babies, the CVD risk in ever-smokers with PTBs (hazard ratio (HR) 3.35, 95% confidence interval (CI) 2.96-3.80) was significantly greater than the sum of risks in ever-smokers with term babies (HR 2.10, 95% CI 1.96-2.24) and in never-smokers with PTBs (HR 1.73, 95% CI 1.55-1.93), indicating an additive interaction (synergy index = 1.29, 95% CI 1.05-1.58). In ever-smokers, the association was stronger for extremely PTB (HR 3.83, 95% CI 3.23-4.69) than moderately PTB (HR 3.18, 95% CI 2.76-3.66), and for ≥2 PTB (HR 4.47, 95% CI 3.39-5.88) than one PTB (HR 3.20, 95% CI 2.81-3.64). CONCLUSION: Maternal smoking and PTB interact on the additive scale to synergistically increase maternal CVD risks. The interaction was dose-dependent according to both the severity and number of PTBs.

Preterm birth and future risk of maternal cardiovascular disease - is the association independent of smoking during pregnancy?

BACKGROUND: While the association of preterm birth and the risk of maternal cardiovascular disease (CVD) has been well-documented, most studies were limited by the inability to account for smoking during pregnancy - an important risk factor for both preterm birth and CVD. This study aimed to determine whether the increased future risk of maternal cardiovascular disease (CVD) associated with preterm birth is independent of maternal smoking during pregnancy. METHODS: A population-based record linkage study of 797,056 women who delivered a singleton infant between 1994 and 2011 in New South Wales, Australia was conducted. Birth records were linked to the mothers' subsequent hospitaliation or death from CVD. Preterm births were categorised as late (35-36 weeks), moderate (33-34 weeks), or extreme (≤32 weeks); and as spontaneous or indicated. Cox proportional hazard regression was used to estimate adjusted hazard ratios (AHR) [95 % CI]. RESULTS: During the study period, 59,563 women (7.5 %) had at least one preterm birth. After adjustment for CVD risk factors other than smoking, AHR [95 % CI] of CVD among women who ever had a preterm birth was 1.78 [1.61-1.96]. Associations were greater for extreme (AHR = 1.98 [1.63-2.42]) and moderate (AHR = 2.06 [1.69-2.51]) than late preterm birth (AHR = 1.63 [1.44-1.85]), for indicated (AHR = 2.04 [1.75-2.38]) than spontaneous preterm birth (AHR = 1.65 [1.47-1.86]), and for having ≥ two (AHR = 2.29[1.75-2.99]) than having one preterm birth (AHR = 1.73[1.57-1.92]). A further adjustment for maternal smoking attenuated, but did not eliminate, the associations. Smoking during pregnancy was also independently associated with maternal CVD risks, with associations being stronger for mothers who smoked during last pregnancy (AHR = 2.07 [1.93-2.23]) than mothers who smoked during a prior pregnancy (AHR = 1.64 [1.41-1.90]). CONCLUSIONS: Associations of preterm birth and maternal CVD risk are independent of maternal smoking during pregnancy. This underscores the importance of smoking cessation in reducing CVD and suggests that a history of preterm delivery (especially if severe, indicated or recurrent) identifies women who could be targeted for CVD screening and preventative therapies.

Red cell and platelet transfusions in neonates: a population-based study.

OBJECTIVES: This study aimed to describe the use of red cells, platelets and exchange transfusions among all neonates in a population cohort, to examine trends in transfusion over time and to determine transfusion rates in at-risk neonates. DESIGN: Linked population-based birth and hospital data from New South Wales (NSW), Australia, were used to determine rates of blood product transfusion in the first 28 days of life. The study included all live births ≥23 weeks' gestation in NSW between 2001 and 2011. RESULTS: Between 2001 and 2011, 5326 of 989 491 live born neonates received a red cell, platelet or exchange transfusion (5.4/1000 births). Transfusion rates were 4.8 per 1000 for red cells, 1.3 per 1000 for platelets and 0.3 per 1000 for exchange transfusion. Overall transfusion rate remained constant from 2001 to 2011 (p=0.27). Among transfused neonates, 60% were <32 weeks' gestation (n=3210, 331/1000 births), 40% were ≥32 weeks' gestation (n= 2116, 2/1000 births) and 7% received transfusions in a hospital without a neonatal intensive care unit (NICU). Factors other than prematurity associated with higher transfusion rates were prior in utero transfusion (631/1000), congenital anomaly requiring surgery (440/1000) and haemolytic disorder (106/1000). CONCLUSIONS: In this population-based study, preterm neonates had a higher rate of transfusion than term neonates; however, 40% of those who received a transfusion were born ≥32 weeks' gestation and 7% were transfused in hospitals without an NICU. These findings need to be considered by transfusion services and personnel developing neonatal transfusion guidelines.

Reduced breast milk feeding subsequent to cosmetic breast augmentation surgery.

OBJECTIVE: To determine the effect of cosmetic breast augmentation on subsequent infant feeding. PARTICIPANTS, DESIGN AND SETTING: Population-based record linkage study of women giving birth in New South Wales, January 2006 - December 2011. Birth records were linked longitudinally to maternal hospitalisations up to 11 years before birth. Breast augmentation was identified by surgical procedure codes in hospital records. MAIN OUTCOME MEASURES: Any breast milk feeding at discharge from birth care, and among infants receiving any breast milk, exclusive breast milk feeding. The before-and-after effect of breast augmentation was assessed among women who had the surgery between births. RESULTS: Among 378 389 women who gave birth in the study period, 892 (0.2%) had prior breast augmentation. Among women with breast augmentation, 705 (79%) provided any breast milk to their infant at discharge, compared with 89% among women without augmentation. After adjusting for sociodemographic and pregnancy factors, infants of women with breast augmentation were less likely to receive breast milk at discharge than infants of women without augmentation (adjusted relative risk [ARR], 0.90; 95% CI, 0.87-0.93). However, infants receiving breast milk were not more or less likely to receive breast milk exclusively (ARR, 0.99; 95% CI, 0.97-1.01). Women with augmentation surgery between births changed their breastfeeding behaviour (reduced rates), while those with no augmentation or augmentation before both births did not. CONCLUSIONS: Reduced rates of breast milk feeding among women who have undergone breast augmentation underscore the importance of identifying, supporting and encouraging women who are vulnerable to a lower likelihood of breastfeeding.

Delivery of a Small-For-Gestational-Age Infant and Risk of Maternal Cardiovascular Disease--A Population-Based Record Linkage Study.

BACKGROUND: Delivery of small for gestational age (SGA) infants has been associated with increased risk of future maternal cardiovascular disease (CVD). However, whether the risk increases progressively with the greater severity of SGA and number of SGA infants has not been explored. METHODS: A population-based record linkage study was conducted among 812,732 women delivering live born, singleton infants at term between 1994 and 2011 in New South Wales, Australia. Birth records were linked to the mothers' subsequent hospitalisation or death records to identify CVD events (coronary heart disease, cerebrovascular events, and chronic heart failure) after a median of 7.4 years. Cox proportional hazard regression was used to estimate adjusted hazard ratios (AHR) [95% confidence interval (CI)] for the associations between the severity (moderate or extreme) of SGA and number of SGA infants and subsequent risk of maternal CVD, accounting for maternal age at last birth, socioeconomic status, parity, smoking, (pre-gestational and gestational) diabetes, and (chronic and pregnancy) hypertension. RESULTS: Compared to mothers of non-SGA infants, AHRs [95%CI] of CVD among mothers of moderately and extremely SGA infants were 1.36 [1.23-1.49], and 1.66 [1.47-1.87], respectively, while AHRs among mothers with 1, 2, and ≥3 SGA infants were 1.42 [1.30-1.54], 1.65 [1.34-2.03], and 2.42 [1.52-3.85], respectively, indicating a dose-response relationship. AHRs of specific CVD categories showed a similar pattern. CONCLUSIONS: Delivery of an SGA infant was associated with a dose-dependent increase in the risk of maternal CVD according to both the severity of SGA and number of previous SGA infants.

Incisional hernia repair after caesarean section: a population-based study.

BACKGROUND: Incisional hernias occur at surgical abdominal incision sites, but the association with caesarean section (CS) has not been examined. AIM: To determine whether CS is a risk factor for incisional hernia repair. MATERIALS AND METHODS: Population-based cohort study in Australia using linked birth and hospital data for women who gave birth from 2000 to 2011. Survival analysis was used to explore the association between CS and subsequent incisional hernia repair. Analyses were adjusted for confounding factors, including other abdominal surgery. The main outcome measure was surgical repair of an incisional hernia. RESULTS: Of 642,578 women, 217,555 (33.9%) had at least one CS and 1,554 (0.2%) women had a subsequent incisional hernia repair. The rate of incisional hernia repair in women who had ever had a caesarean section was 0.47%, compared to 0.12% in women who never had a caesarean section. After controlling for the duration of follow-up and known explanatory variables (eg other abdominal surgery, parity and multiple pregnancy), the adjusted hazard ratio (aHR) was 2.73 (95% confidence interval (CI) 2.45-3.06, P < 0.001). Incisional hernia repair risk increased with number of caesarean sections: women with two CS had a threefold increased risk of incisional hernia repair, which increased to sixfold after five CS (aHR = 6.29, 95% CI 3.99-9.93, P < 0.001) compared to women with no CS. CONCLUSIONS: There was a strong association between maternal CS and subsequent incisional hernia repair, which increased as the number of CSs increased, but the absolute risk of incisional hernia repair was low.

Evaluation of first trimester serum soluble endothelial cell-specific tyrosine kinase receptor in normal and affected pregnancies.

AIMS: To assess soluble endothelial cell-specific tyrosine kinase receptor (sTie-2) levels in the first trimester of pregnancy and its association with adverse pregnancy outcomes; and examine the predictive accuracy. STUDY DESIGN: In this nested case-control study, serum sTie-2 levels were measured in 2616 women with singleton pregnancies attending first trimester screening in New South Wales, Australia. Multivariate logistic regression models were used to assess the association and predictive accuracy of serum sTie-2 with subsequent adverse pregnancy outcomes. RESULTS: Median (interquartile range) sTie-2 for the total population was 19.6 ng/ml (13.6-26.4). Maternal age, weight, and smoking status significantly affected sTie-2 levels. There was no difference in serum sTie-2 between unaffected and women with adverse pregnancy outcomes. After adjusting for maternal and clinical risk factors, low sTie-2 (<25th centile) was associated with preeclampsia (Adjusted odds ratio: 1.61; 95% CI: 1.01-2.57), however, the accuracy of sTie-2 in predicting preeclampsia was not different from chance (AUC = 0.54; p = 0.08) and does not add valuable predictive information to maternal and clinical risk factors. CONCLUSIONS: Our findings suggest that low sTie-2 levels are associated with preeclampsia, however, it does not add valuable information to clinical and maternal risk factor information in predicting preeclampsia or any other adverse pregnancy outcomes.

Incidence and outcomes of pregnancy-associated melanoma in New South Wales 1994-2008.

BACKGROUND: There is controversy about the interaction between melanoma and pregnancy. There is a lack of Australian data on pregnancy outcomes associated with melanoma in pregnancy, despite Australia having the highest incidence of melanoma in the world. AIMS: Describe trends, maternal characteristics and pregnancy outcomes associated with pregnancy-associated melanoma in New South Wales. MATERIALS AND METHODS: Population-based cohort study of all births (n = 1 309 501) of at least 20-week gestation or 400 g birthweight in New South Wales, 1994-2008. Logistic regression was used to analyse the association between melanoma in pregnancy and adverse birth outcomes. RESULTS: 577 pregnancy-associated melanomas were identified, including 195 diagnosed during pregnancy and 382 diagnosed within 12 months postpartum. The crude incidence of pregnancy-associated melanoma increased from 37.1 per 100 000 maternities in 1994 to 51.84 per 100 000 maternities in 2008. Adjusting for maternal age accounted for the trend in pregnancy-associated melanoma. Melanomas diagnosed in pregnancy were thicker (median = 0.75 mm) than melanomas diagnosed postpartum (median = 0.60 mm) (P = 0.002). Pregnancy-associated melanoma was associated with the increased risk of large-for-gestational-age infant but not preterm birth, planned birth, caesarean section or stillbirth. Parity was inversely associated with pregnancy-associated melanoma, as women with three or more previous pregnancies had 0.59 times the odds of pregnancy-associated melanoma compared to nulliparous women (95% CI 0.42-0.84, P = 0.003). CONCLUSIONS: The incidence of pregnancy-associated melanoma has increased with increasing maternal age. The observation of thicker melanomas in pregnancy and increased risk of large-for-gestational-age infants may suggest a role for growth-related pregnancy factors in pregnancy-associated melanoma.

The impact of cosmetic breast implants on breastfeeding: a systematic review and meta-analysis.

BACKGROUND: Cosmetic breast augmentation (breast implants) is one of the most common plastic surgery procedures worldwide and uptake in high income countries has increased in the last two decades. Women need information about all associated outcomes in order to make an informed decision regarding whether to undergo cosmetic breast surgery. We conducted a systematic review to assess breastfeeding outcomes among women with breast implants compared to women without. METHODS: A systematic literature search of Medline, Pubmed, CINAHL and Embase databases was conducted using the earliest inclusive dates through December 2013. Eligible studies included comparative studies that reported breastfeeding outcomes (any breastfeeding, and among women who breastfed, exclusive breastfeeding) for women with and without breast implants. Pairs of reviewers extracted descriptive data, study quality, and outcomes. Rate ratios (RR) and 95% confidence intervals (CI) were pooled across studies using the random-effects model. The Newcastle-Ottawa scale (NOS) was used to critically appraise study quality, and the National Health and Medical Research Council Level of Evidence Scale to rank the level of the evidence. This systematic review has been registered with the international prospective register of systematic reviews (PROSPERO): CRD42014009074. RESULTS: Three small, observational studies met the inclusion criteria. The quality of the studies was fair (NOS 4-6) and the level of evidence was low (III-2 - III-3). There was no significant difference in attempted breastfeeding (one study, RR 0.94, 95% CI 0.76, 1.17). However, among women who breastfed, all three studies reported a reduced likelihood of exclusive breastfeeding amongst women with breast implants with a pooled rate ratio of 0.60 (95% CI 0.40, 0.90). CONCLUSIONS: This systematic review and meta-analysis suggests that women with breast implants who breastfeed were less likely to exclusively feed their infants with breast milk compared to women without breast implants.

Maternal body weight and first trimester screening for chromosomal anomalies.

Prenatal risk ratios for Down syndrome adjust for maternal weight because maternal serum biomarker levels decrease with increasing maternal weight. This is accomplished by converting serum biomarker values into a multiple of the expected median (MoM) for women of the same gestational age. Weight is frequently not recorded, and the impact of using MoMs not adjusted for weight for calculating risk ratios is unknown. The aim of this study is to examine the effect of missing weight on first trimester Down syndrome risk ratios by comparing risk ratios calculated using weight-unadjusted-and-adjusted MoMs. Findings at the population level indicate that the impact of not adjusting for maternal weight on first trimester screening results for chromosomal anomalies would lead to under-identification of 84 per 10,000 pregnancies.

Trends in New South Wales infant hospital readmission rates in the first year of life: a population-based study.

OBJECTIVE: To examine the trends in hospital readmissions in the first year of life and identify whether changes in maternal and infant risk factors explain any changes. DESIGN: Population-based study using de-identified linked health data. PARTICIPANTS: All 788 798 live-born infants delivered in New South Wales from 1 January 2001 to 31 December 2009 with a linked birth and hospital record. MAIN OUTCOME MEASURES: The number of infants readmitted to hospital at least once after discharge home from the birth admission to 1 year of age, per 100 live births each year, and changes in maternal and infant risk factors assessed by logistic regression. RESULTS: The number of infants readmitted to hospital up to age 1 year decreased by 10.5% (average annual reduction, 1.8%; 95% CI, - 1.7% to - 0.01%, P = 0.001), from 18.4 per 100 births in 2001 to 16.5 in 2009. Fifty-five per cent of this decrease could be explained by changes in factors that are associated with likelihood of hospitalisation; length of stay during the birth admission, maternal age and maternal smoking. The rate of readmissions for jaundice and feeding difficulties increased significantly over the study period, while readmissions for infections decreased. CONCLUSIONS: There has been a decrease in the rate of infants readmitted to hospital in the first year of life, which can be partly explained by increasing maternal age, decreasing maternal smoking and a shift to shorter length of hospital stay at birth. Improved maternal and neonatal care in hospital and increased postnatal support at home may have contributed to reduced risk of readmission.

Linking birth records to hospital admission records enhances the identification of women who smoke during pregnancy.

OBJECTIVE: Birth records and hospital admission records are valuable for research on maternal smoking, but individually are known to under-estimate smokers. This study investigated the extent to which combining data from these records enhances the identification of pregnant smokers, and whether this affects research findings such as estimates of maternal smoking prevalence and risk of adverse pregnancy outcomes associated with smoking. METHODS: A total of 846,039 birth records in New South Wales, Australia, (2001-2010) were linked to hospital admission records (delivery and antenatal). Algorithm 1 combined data from birth and delivery admission records, whereas algorithm 2 combined data from birth record, delivery and antenatal admission records. Associations between smoking and placental abruption, preterm birth, stillbirth, and low birthweight were assessed using multivariable logistic regression. RESULTS: Algorithm 1 identified 127,612 smokers (smoking prevalence 15.1%), which was a 9.6% and 54.6% increase over the unenhanced identification from birth records alone (prevalence 13.8%), and delivery admission records alone (prevalence 9.8%), respectively. Algorithm 2 identified a further 2,408 smokers from antenatal admission records. The enhancement varied by maternal socio-demographic characteristics (age, marital status, country of birth, socioeconomic status); obstetric factors (multi-fetal pregnancy, diabetes, hypertension); and maternity hospital. Enhanced and unenhanced identification methods yielded similar odds ratios for placental abruption, preterm birth, stillbirth and low birthweight. CONCLUSIONS: Use of linked data improved the identification of pregnant smokers. Studies relying on a single data source should adjust for the under-ascertainment of smokers among certain obstetric populations.

Rate of spontaneous onset of labour before planned repeat caesarean section at term.

BACKGROUND: Guidelines recommend that, in the absence of compelling medical indications (low risk) elective caesarean section should occur after 38 completed weeks gestation. However, implementation of these guidelines will mean some women go into labour before the planned date resulting in an intrapartum caesarean section. The aim of this study was to determine the rate at which low-risk women planned for repeat caesarean section go into spontaneous labour before 39 weeks. METHODS: We conducted a population-based cohort study of women who were planned to have an elective repeat caesarean section (ERCS) at 39-41 weeks gestation in New South Wales Australia, 2007-2010. Labour, delivery and health outcome information was obtained from linked birth and hospital records for the entire population. Women with no pre-existing medical or pregnancy complications were categorized as 'low risk'. The rate of spontaneous labour before 39 weeks was determined and variation in the rate for subgroups of women was examined using univariate and multivariate analysis. RESULTS: Of 32,934 women who had ERCS as the reported indication for caesarean section, 17,314 (52.6%) were categorised as 'low-risk'. Of these women, 1,473 (8.5% or 1 in 12) had spontaneous labour or prelabour rupture of the membranes before 39 weeks resulting in an intrapartum caesarean section. However the risk of labour <39 weeks varied depending on previous delivery history: 25% (1 in 4) for those with spontaneous preterm labour in a prior pregnancy; 15% (1 in 7) for women with a prior planned preterm birth (by labour induction or prelabour caesarean) and 6% (1 in 17) among those who had only previously had a planned caesarean section at term. Smoking in pregnancy was also associated with spontaneous labour. Women with spontaneous labour prior to a planned CS in the index pregnancy were at increased risk of out-of-hours delivery, and maternal and neonatal morbidity. CONCLUSIONS: These findings allow clinicians to more accurately determine the likelihood that a planned caesarean section may become an intrapartum caesarean section, and to advise their patients accordingly.

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

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