A validation of placental pathology reports by ethnicity in New Zealand, through systematic analysis of histological slides.

INTRODUCTION: Reliability studies of placental examination have shown differing interobserver agreement for certain pathological features, a lack of uniform reporting criteria and variable experience among pathologists. In previous analyses we have shown that placental pathology differs by ethnicity. This validation study was performed to investigate whether bias related to ethnicity is a feature of placental pathology reporting in New Zealand (NZ). METHODS: 199 of 1726 eligible perinatal death cases between 2008 and 2017 were selected at random for this audit-type study, including 51 cases from South Asian, Maori and NZ European ethnicity and 46 cases from Pacific mothers. Stored histology slides were blinded and re-examined by an experienced perinatal pathologist, and linked to the corresponding original pathology report. Interobserver agreement (overall, by ethnicity and by gestational age) was described by proportional differences and kappa coefficients. RESULTS: Total interobserver agreement between original placental reporting and the validation review was 89.7 %, which differed by pathological feature. There was generally more underreporting than overreporting (3.6 % and 6.7 %, respectively). There was little disagreement by ethnicity (decidual vasculopathy [p = 0.03]), although there were more differences by gestational age (villous morphology [p < 0.01], chorioamnionitis [p = 0.03], high-grade villitis of unknown etiology [p < 0.01], and placental haemorrhage [p = 0.03]). DISCUSSION: No systematic bias in placental pathology reporting in NZ was identified by ethnicity or gestational age, as observed differences could be related to the underlying prevalence of pathology. We identified more underreporting than overreporting of pathology in the original reports, emphasizing the importance of placental investigation by specialised perinatal pathologists.

An in-depth analysis of perinatal related mortality among women of South Asian ethnicity in Aotearoa New Zealand.

BACKGROUND: International and national New Zealand (NZ) research has identified women of South Asian ethnicity at increased risk of perinatal mortality, in particular stillbirth, with calls for increased perinatal research among this ethnic group. We aimed to analyse differences in pregnancy outcomes and associated risk factors between South Asian, Maori, Pacific and NZ European women in Aotearoa NZ, with a focus on women of South Asian ethnicity, to ultimately understand the distinctive pathways leading to adverse events. METHODS: Clinical data from perinatal deaths between 2008 and 2017 were provided by the NZ Perinatal and Maternal Mortality Review Committee, while national maternity and neonatal data, and singleton birth records from the same decade, were linked using the Statistics NZ Integrated Data Infrastructure for all births. Pregnancy outcomes and risk factors for stillbirth and neonatal death were compared between ethnicities with adjustment for pre-specified risk factors. RESULTS: Women of South Asian ethnicity were at increased risk of stillbirth (aOR 1.51, 95%CI 1.29-1.77), and neonatal death (aOR 1.51, 95%CI 1.17-1.92), compared with NZ European. The highest perinatal related mortality rates among South Asian women were between 20-23 weeks gestation (between 0.8 and 1.3/1,000 ongoing pregnancies; p < 0.01 compared with NZ European) and at term, although differences by ethnicity at term were not apparent until ≥ 41 weeks (p < 0.01). No major differences in commonly described risk factors for stillbirth and neonatal death were observed between ethnicities. Among perinatal deaths, South Asian women were overrepresented in a range of metabolic-related disorders, such as gestational diabetes, pre-existing thyroid disease, or maternal red blood cell disorders (all p < 0.05 compared with NZ European). CONCLUSIONS: Consistent with previous reports, women of South Asian ethnicity in Aotearoa NZ were at increased risk of stillbirth and neonatal death compared with NZ European women, although only at extremely preterm (< 24 weeks) and post-term (≥ 41 weeks) gestations. While there were no major differences in established risk factors for stillbirth and neonatal death by ethnicity, metabolic-related factors were more common among South Asian women, which may contribute to adverse pregnancy outcomes in this ethnic group.

Placental pathology findings in perinatal deaths from 28 weeks gestation in Aotearoa New Zealand.

INTRODUCTION: Women of South Asian ethnicity are overrepresented in adverse pregnancy outcome across high-income countries, including those related to placental dysfunction. It has been hypothesised that placental aging occurs at earlier gestation in South Asian pregnancies. We aimed to identify differences in placental pathology among perinatal deaths ≥28 weeks gestation, between South Asian, Maori and New Zealand (NZ) European women in Aotearoa NZ, with a focus on women of South Asian ethnicity. METHODS: Placental pathology reports and clinical data from perinatal deaths between 2008 and 2017 were provided by the NZ Perinatal and Maternal Mortality Review Committee, blinded, and analysed by an experienced perinatal pathologist using the Amsterdam Placental Workshop Group Consensus Statement criteria. RESULTS: 790 of 1161 placental pathology reports, 346 preterm (28+0 to 36+6 weeks) and 444 term (≥37+0 weeks) deaths, met the inclusion criteria. Among preterm deaths, South Asian women had higher rates of maternal vascular malperfusion compared with Maori (aOR 4.16, 95%CI 1.55-11.15) and NZ European (aOR 2.60, 95%CI 1.10-6.16). Among term deaths, South Asian women had higher rates of abnormal villous morphology compared with Maori (aOR 2.19, 95%CI 1.04-4.62) and NZ European (aOR 2.12, 95%CI 1.14-3.94), mostly due to increased rates of chorangiosis (36.7%, compared to 23.3% and 21.7%, respectively). DISCUSSION: Differences in placental pathology by ethnicity were observed among preterm and term perinatal deaths. While we suspect differing underlying causal pathways, these deaths may be associated with maternal diabetic and red blood cell disorders among South Asian women, leading to a hypoxic state in-utero.

Placental pathology findings amongst extremely preterm perinatal deaths in Aotearoa New Zealand.

INTRODUCTION: Women of South Asian ethnicity are overrepresented in adverse pregnancy outcomes across high-income countries, including placental dysfunction and antepartum haemorrhage. As the burden of mortality is highest for extremely preterm infants, we aimed to identify any differences in placental pathology among perinatal deaths from 20+0 to 27+6 weeks gestation between South Asian, Maori and New Zealand (NZ) European women in Aotearoa NZ, with a focus on women of South Asian ethnicity. METHODS: Placental pathology reports and clinical data from perinatal deaths between 2008 and 2017 were provided by the NZ Perinatal and Maternal Mortality Review Committee, blinded and analysed by an experienced perinatal pathologist using the Amsterdam Placental Workshop Group Consensus Statement criteria. South Asian ethnicity was classified as Indian, Fijian Indian, South African Indian, Sri Lankan, Pakistani and Bangladeshi. RESULTS: 886 of 1571 placental pathology reports met the inclusion criteria. Women of South Asian ethnicity were significantly more likely to show features of histologic chorioamnionitis (aOR 1.87, 95%CI 1.19-2.94) and chorionic vasculitis (aOR 1.92, 95%CI 1.13-3.29), than NZ European and Maori women respectively. 13 of 15 (87%) of South Asian mothers with a diabetic disorder were identified with chorioamnionitis, compared to 1 in 5 (20%) of Maori and 5 in 12 (41%) of NZ European women. Cord hyper-coiling was also more common among South Asian pregnancies, compared to NZ European (aOR 1.98, 95%CI 1.10-3.56). DISCUSSION: Differences in placental pathology by ethnicity were observed among extremely preterm perinatal deaths. Underlying metabolic disorders and an associated pro-inflammatory environment may play an important role in the causal pathway leading to these deaths in women of South Asian ethnicity.

Risk factors for late preterm and term stillbirth: A secondary analysis of an individual participant data meta-analysis.

OBJECTIVE: Identify independent and novel risk factors for late-preterm (28-36 weeks) and term (≥37 weeks) stillbirth and explore development of a risk-prediction model. DESIGN: Secondary analysis of an Individual Participant Data (IPD) meta-analysis investigating modifiable stillbirth risk factors. SETTING: An IPD database from five case-control studies in New Zealand, Australia, the UK and an international online study. POPULATION: Women with late-stillbirth (cases, n = 851), and ongoing singleton pregnancies from 28 weeks' gestation (controls, n = 2257). METHODS: Established and novel risk factors for late-preterm and term stillbirth underwent univariable and multivariable logistic regression modelling with multiple sensitivity analyses. Variables included maternal age, body mass index (BMI), parity, mental health, cigarette smoking, second-hand smoking, antenatal-care utilisation, and detailed fetal movement and sleep variables. MAIN OUTCOME MEASURES: Independent risk factors with adjusted odds ratios (aOR) for late-preterm and term stillbirth. RESULTS: After model building, 575 late-stillbirth cases and 1541 controls from three contributing case-control studies were included. Risk factor estimates from separate multivariable models of late-preterm and term stillbirth were compared. As these were similar, the final model combined all late-stillbirths. The single multivariable model confirmed established demographic risk factors, but additionally showed that fetal movement changes had both increased (decreased frequency) and reduced (hiccoughs, increasing strength, frequency or vigorous fetal movements) aOR of stillbirth. Poor antenatal-care utilisation increased risk while more-than-adequate care was protective. The area-under-the-curve was 0.84 (95% CI 0.82-0.86). CONCLUSIONS: Similarities in risk factors for late-preterm and term stillbirth suggest the same approach for risk-assessment can be applied. Detailed fetal movement assessment and inclusion of antenatal-care utilisation could be valuable in late-stillbirth risk assessment.

A comprehensive methodology report for maternity and perinatal mortality research in the New Zealand Integrated Data Infrastructure.

AIM: The highest quality perinatal data in New Zealand is collected and collated by the Perinatal and Maternal Mortality Review Committee (PMMRC) and is made available to a limited number of researchers. Therefore, maternity, and perinatal mortality studies are generally performed on Government-held data. This report offers an alternative approach with in-depth justification for the methodology, while simultaneously improving the understanding of the data sources. METHOD: A standardised method for creating a comprehensive maternity dataset within the Statistics New Zealand Integrated Data Infrastructure (IDI) was developed and a validation dataset was created to include all births between 2008 and 2017. RESULTS: A close approximation to the PMMRC annual report data was found, with 4.0% over-reporting of perinatal deaths and 0.05% over-reporting of live births in the IDI dataset. Several variables, including important pregnancy risk factors, were validated for use. Limitations to the datasets were explored and additional tables in the IDI were proposed, to include variables on pregnancy complications, ethnicity and country of birth, and socio-economic data. CONCLUSION: This methodological report describes an opportunity for standardised, high-quality maternity research in New Zealand using the IDI, including a variety of national data sources. Recommendations for further enhancement of these resources have been offered.

Grouping women of South Asian ethnicity for pregnancy research in New Zealand.

BACKGROUND: The New Zealand (NZ) Ministry of Health ethnicity data protocols recommend that people of South Asian (SAsian) ethnicity, other than Indian, are combined with people of Japanese and Korean ethnicity at the most commonly used level of aggregation in health research (level two). This may not work well for perinatal studies, as it has long been observed that women of Indian ethnicity have higher rates of adverse pregnancy outcomes, such as perinatal death. It is possible that women of other SAsian ethnicities share this risk. AIMS: This study was performed to identify appropriate groupings of women of SAsian ethnicity for perinatal research. MATERIALS AND METHODS: National maternity and neonatal data, and singleton birth records between 2008 and 2017 were linked using the Statistics NZ Integrated Data Infrastructure. Socio-demographic risk profiles and pregnancy outcomes were compared between 15 ethnic groups. Recommendations were made based on statistical analyses and cultural evaluation with members of the SAsian research community. RESULTS: Similarities were observed between women of Indian, Fijian Indian, South African Indian, Sri Lankan, Bangladeshi and Pakistani ethnicities. A lower-risk profile was seen among Japanese and Korean mothers. Risk profiles of women of combined Indian-Maori, Indian-Pacific and Indian-New Zealand European ethnicity more closely represented their corresponding non-Indian ethnicities. CONCLUSIONS: Based on these findings, we suggest a review of current NZ Ministry of Health ethnicity data protocols. We recommend that researchers understand the risk profiles of participants prior to aggregation of groups in research, to mitigate risks associated with masking differences.

Accuracy of ultrasound in the estimation of customised birth weight in a public hospital service.

INTRODUCTION: Studies have shown that ultrasound estimated foetal weight (EFW) in small for gestational age (SGA) babies tends to be less-accurate when compared to appropriate (AGA) and large (LGA) for gestational age babies. We aimed to analyse the accuracy of ultrasound EFW overall, and by customised birth weight centile category (severe SGA, SGA, AGA, LGA). Also, the accuracy of estimating the centile category using calculated customised EFW centiles. METHODS: We performed a retrospective study of pregnant women between 20-43 weeks gestation who underwent ultrasound within 7 days of delivery at a large tertiary maternity unit between January 2018 and December 2020. Stillbirths, major foetal anomalies and multiple pregnancies were excluded. The EFW and birth weight were compared, and an accurate estimate defined as ≤15% difference. The customised EFW and birth weight centiles were calculated and used to analyse the accuracy of category prediction. RESULTS: Of 2061 foetuses included, 92% (n = 1902) were born weighing within 15% of their EFW. Accuracy was not affected by maternal BMI, ethnicity, parity or gestation. 87% of SGA babies were within 15% of their EFW. Ultrasound sensitivity for SGA was 51% (95% CI: 46-55%). The specificity and positive predictive values were 97% (95% CI: 96-98%) and 87% (95% CI: 82-90%) respectively. CONCLUSION: The accuracy of Ultrasound EFW overall is good, however, is reduced in SGA babies whose EFW and birth weight centile categories tended to be overestimated. The high specificity for SGA supports monitoring with a lowered threshold to intervene in pregnancies identified by ultrasound as SGA.

Reduction in perinatal mortality among small for gestational age babies in New Zealand.

BACKGROUND: A significant reduction in perinatal mortality among births ≥1000 g has been observed in New Zealand. AIM: To determine, in a national cohort, if perinatal mortality has reduced in small for gestational age (SGA) and non-SGA babies. MATERIALS AND METHODS: Retrospective cohort, 2008-2016, of singleton non-anomalous births and perinatal deaths from 26+0 weeks gestation at birth in New Zealand. Perinatal deaths from the Perinatal and Maternal Mortality Review Committee data set were merged with the Ministry of Health national maternity data set. SGA was defined as less than the 10th customised birthweight centile using New Zealand coefficients. Perinatal mortality was defined as stillbirth from 26 weeks gestation and neonatal death up to the 27th day of life. RESULTS: There was a 30% reduction in perinatal mortality among SGA singleton non-anomalous babies at 26 weeks or more from 10.38/1000 births in 2008 to 7.28/1000 in 2016 (P = 0.046) but no significant change in mortality among appropriate and large for gestational age babies. CONCLUSION(S): There has been a significant reduction in perinatal mortality among SGA babies in New Zealand. The mechanism for this reduction is unclear.

Neonatal morbidity and small and large size for gestation: a comparison of birthweight centiles.

OBJECTIVE: To compare rates of small- and large-for-gestational age (SGA and LGA) neonates using four different weight centiles, and to relate these classifications to neonatal morbidity. STUDY DESIGN: Neonates born at 33-40 weeks' gestation in a multiethnic population were classified as SGA or LGA by population reference (Fenton), population standard (INTERGROWTH), fetal growth curves (WHO), and customized (GROW) centiles. Likelihood of composite morbidity was determined compared with a common appropriate-for-gestational age referent group. RESULT: Among 45,505 neonates, SGA and LGA rates varied up to threefold by different centiles. Those most likely to develop neonatal morbidity were SGA or LGA on both the population reference and an alternative centile. Customized centiles identified over twice as many at-risk SGA neonates. CONCLUSIONS: Customized centiles were most useful in identifying neonates at increased risk of morbidity, and those that were small on both customized and population reference centiles were at the highest risk.

Association of Supine Going-to-Sleep Position in Late Pregnancy With Reduced Birth Weight: A Secondary Analysis of an Individual Participant Data Meta-analysis.

Importance: Supine maternal position in the third trimester is associated with reduced uterine blood flow and increased risk of late stillbirth. As reduced uterine blood flow is also associated with fetal growth restriction, this study explored the association between the position in which pregnant women went to sleep and infant birth weight. Objective: To examine the association between supine position when going to sleep in women after 28 weeks of pregnancy and lower birth weight and birth weight centiles. Design, Setting, and Participants: Prespecified subgroup analysis using data from controls in an individual participant data meta-analysis of 4 case-control studies investigating sleep and stillbirth in New Zealand, Australia, and the United Kingdom. Participants were women with ongoing pregnancies at 28 weeks' gestation or more at interview. Main Outcomes and Measures: The primary outcome was adjusted mean difference (aMD) in birth weight. Secondary outcomes were birth weight centiles (INTERGROWTH-21st and customized) and adjusted odds ratios (aORs) for birth weight less than 50th and less than 10th centile (small for gestational age) for supine vs nonsupine going-to-sleep position in the last 1 to 4 weeks, adjusted for variables known to be associated with birth size. Results: Of 1760 women (mean [SD] age, 30.25 [5.46] years), 57 (3.2%) reported they usually went to sleep supine during the previous 1 to 4 weeks. Adjusted mean (SE) birth weight was 3410 (112) g among women who reported supine position and 3554 (98) g among women who reported nonsupine position (aMD, 144 g; 95% CI, -253 to -36 g; P = .009), representing an approximate 10-percentile reduction in adjusted mean INTERGROWTH-21st (48.5 vs 58.6; aMD, -10.1; 95% CI, -17.1 to -3.1) and customized (40.7 vs 49.7; aMD, -9.0; 95% CI, -16.6 to -1.4) centiles. There was a nonsignificant increase in birth weight at less than the 50th INTERGROWTH-21st centile (aOR, 1.90; 95% CI, 0.83-4.34) and a 2-fold increase in birth weight at less than the 50th customized centile (aOR, 2.12; 95% CI, 1.20-3.76). Going to sleep supine was associated with a 3-fold increase in small for gestational age birth weight by INTERGROWTH-21st standards (aOR, 3.23; 95% CI, 1.37-7.59) and a nonsignificant increase in small for gestational age birth weight customized standards (aOR, 1.63; 95% CI, 0.77-3.44). Conclusions and Relevance: This study found that going to sleep in a supine position in late pregnancy was independently associated with reduced birth weight and birth weight centile. This novel association is biologically plausible and likely modifiable. Public health campaigns that encourage women in the third trimester of pregnancy to settle to sleep on their side have potential to optimize birth weight.

An Individual Participant Data Meta-analysis of Maternal Going-to-Sleep Position, Interactions with Fetal Vulnerability, and the Risk of Late Stillbirth.

BACKGROUND: Maternal supine going-to-sleep position has been associated with increased risk of late stillbirth (≥ 28 weeks), but it is unknown if the risk differs between right and left side, and if some pregnancies are more vulnerable. METHODS: Systematic searches were undertaken for an individual-level participant data (IPD) meta-analysis of case-control studies, prospective cohort studies and randomised trials undertaken up until 26 Jan, 2018, that reported data on maternal going-to-sleep position and stillbirth. Participant inclusion criteria included gestation ≥ 28 weeks', non-anomalous, singleton pregnancies. The primary outcome was stillbirth. A one-stage approach stratified by study and site was used for the meta-analysis. The interaction between supine going-to-sleep position and fetal vulnerability was assessed by bi-variable regression. The multivariable model was adjusted for a priori confounders. Registration number: PROSPERO, CRD42017047703. FINDINGS: Six case-control studies were identified, with data obtained from five (cases, n = 851; controls, n = 2257). No data was provided by a sixth study (cases, n = 100; controls, n = 200). Supine going-to-sleep position was associated with increased odds of late stillbirth (adjusted odds ratio [aOR] 2.63, 95% CI 1.72-4.04, p < 0.0001) compared with left side. Right side had similar odds to left (aOR 1.04, 95% CI 0.83-1.31, p = 0.75). There were no significant interactions between supine going-to-sleep position and assessed indicators of fetal vulnerability, including small-for-gestational-age infants (p = 0.32), maternal obesity (p = 0.08), and smoking (p = 0.86). The population attributable risk for supine going-to-sleep position was 5.8% (3.2-9.2). INTERPRETATION: This IPD meta-analysis confirms that supine going-to-sleep position is independently associated with late stillbirth. Going-to-sleep on left or right side appears equally safe. No significant interactions with our assessed indicators of fetal vulnerability were identified, therefore, supine going-to-sleep position can be considered a contributing factor for late stillbirth in all pregnancies. This finding could reduce late stillbirth by 5.8% if every pregnant woman ≥ 28 weeks' gestation settled to sleep on her side.

Placental growth factor as an indicator of fetal growth restriction in late-onset small-for-gestational age pregnancies.

BACKGROUND: At-risk small-for-gestational age (SGA) pregnancies in New Zealand are identified using Doppler ultrasound; fetuses with Doppler abnormalities are considered growth restricted (FGR). Low maternal placental growth factor (PlGF) has also been associated with late-onset FGR. AIMS: To investigate whether low PlGF at diagnosis of late-onset SGA identifies the same fetuses classified FGR by detailed Doppler studies, and the association between low PlGF and adverse pregnancy outcomes. METHODS: Among an historical database of normotensive suspected SGA pregnancies (fetal abdominal circumference <10th percentile) ≥32 weeks gestation, the ability of low PlGF (<5th percentile) to identify FGR infants was investigated. 'Initial FGR' was an abnormal umbilical artery resistance index (RI) or estimated fetal weight <3rd customised centile. 'Secondary FGR' was abnormal internal carotid RI, cerebro-placental ratio and/or mean uterine artery RI. Development of hypertensive disease and adverse perinatal outcomes were compared by PlGF status. RESULTS: Of 136 SGA pregnancies, 56 (41.1%) had initial FGR. Of the remaining, 20 (25.0%) had secondary FGR, 17 (21.3%) low PlGF. The sensitivity of low PlGF identifying secondary FGR was 0.30 (95% CI 0.14-0.50), specificity 0.83 (0.70-0.92), positive predictive value 0.47 (0.23-0.72) and negative predictive value 0.70 (0.57-0.81). Overall, low PlGF occurred in 44/136 (32.4%) pregnancies and was associated with gestational hypertensive disease (63.6% vs 15.2%, P < 0.01), adverse perinatal outcome (34.1% vs 15.2%, P = 0.01) and very low birthweight (customised centile 2.2 vs 6.8, P < 0.01). CONCLUSIONS: At diagnosis of late-onset SGA, low PlGF was poor at identifying Doppler-defined FGR. Low PlGF identified pregnancies at risk of hypertensive disease, adverse perinatal outcome and very low birthweight.

Evidence-based national guidelines for the management of suspected fetal growth restriction: comparison, consensus, and controversy.

Small for gestational age is usually defined as an infant with a birthweight <10th centile for a population or customized standard. Fetal growth restriction refers to a fetus that has failed to reach its biological growth potential because of placental dysfunction. Small-for-gestational-age babies make up 28-45% of nonanomalous stillbirths, and have a higher chance of neurodevelopmental delay, childhood and adult obesity, and metabolic disease. The majority of small-for-gestational-age babies are not recognized before birth. Improved identification, accompanied by surveillance and timely delivery, is associated with reduction in small-for-gestational-age stillbirths. Internationally and regionally, detection of small for gestational age and management of fetal growth problems vary considerably. The aim of this review is to: summarize areas of consensus and controversy between recently published national guidelines on small for gestational age or fetal growth restriction; highlight any recent evidence that should be incorporated into existing guidelines; and identify future research priorities in this field. A search of MEDLINE, Google, and the International Guideline Library identified 6 national guidelines on management of pregnancies complicated by fetal growth restriction/small for gestational age published from 2010 onwards. There is general consensus between guidelines (at least 4 of 6 guidelines in agreement) in early pregnancy risk selection, and use of low-dose aspirin for women with major risk factors for placental insufficiency. All highlight the importance of smoking cessation to prevent small for gestational age. While there is consensus in recommending fundal height measurement in the third trimester, 3 specify the use of a customized growth chart, while 2 recommend McDonald rule. Routine third-trimester scanning is not recommended for small-for-gestational-age screening, while women with major risk factors should have serial scanning in the third trimester. Umbilical artery Doppler studies in suspected small-for-gestational-age pregnancies are universally advised, however there is inconsistency in the recommended frequency for growth scans after diagnosis of small for gestational age/fetal growth restriction (2-4 weekly). In late-onset fetal growth restriction (≥32 weeks) general consensus is to use cerebral Doppler studies to influence surveillance and/or delivery timing. Fetal surveillance methods (most recommend cardiotocography) and recommended timing of delivery vary. There is universal agreement on the use of corticosteroids before birth at <34 weeks, and general consensus on the use of magnesium sulfate for neuroprotection in early-onset fetal growth restriction (<32 weeks). Most guidelines advise using cardiotocography surveillance to plan delivery in fetal growth restriction <32 weeks. The recommended gestation at delivery for fetal growth restriction with absent and reversed end-diastolic velocity varies from 32 to ≥34 weeks and 30 to ≥34 weeks, respectively. Overall, where there is high-quality evidence from randomized controlled trials and meta-analyses, eg, use of umbilical artery Doppler and corticosteroids for delivery <34 weeks, there is a high degree of consistency between national small-for-gestational-age guidelines. This review discusses areas where there is potential for convergence between small-for-gestational-age guidelines based on existing randomized controlled trials of management of small-for-gestational-age pregnancies, and areas of controversy. Research priorities include assessing the utility of late third-trimester scanning to prevent major morbidity and mortality and to investigate the optimum timing of delivery in fetuses with late-onset fetal growth restriction and abnormal Doppler parameters. Prospective studies are needed to compare new international population ultrasound standards with those in current use.

INTERGROWTH-21st vs customized birthweight standards for identification of perinatal mortality and morbidity.

BACKGROUND: The recently published INTERGROWTH-21st Project international population standard for newborn size is intended for global use, but its ability to identify small infants at risk of adverse outcomes in a general obstetric population has not been reported. OBJECTIVE: The objective of the study was to compare adverse neonatal outcomes among small-for-gestational-age (SGA) infants between the INTERGROWTH-21st standard and a customized birthweight standard (accounting for maternal characteristics of height, weight, parity, and ethnicity). We hypothesized that in a multiethnic general obstetric population in Auckland, New Zealand, a customized birthweight standard would better identify SGA infants at-risk of neonatal morbidity/mortality and stillbirth than the INTERGROWTH-21st standard. STUDY DESIGN: Using prospectively gathered maternity data from a general obstetric population in Auckland, New Zealand, from 2006 to 2013 (n = 53,484 births at ≥ 33 weeks), infants were classified as SGA (birthweight < 10th centile) by INTERGROWTH-21st and customized standards. Infants were further categorized as SGA by both criteria, INTERGROWTH-21st only, customized only, or not SGA (met neither criteria). Composite adverse neonatal outcome was defined as neonatal death, neonatal intensive care admission > 48 hours, or ventilation > 4 hours or 5-minute Apgar score < 7. Relative risks for primary outcomes were estimated using modified Poisson regression, with the non-SGA group as the referent. RESULTS: Incidence of SGA was 4.5% by INTERGROWTH-21st and 11.6% by customized standard. Compared with those not SGA, infants identified as small for gestational age by both criteria had the highest risk of adverse neonatal outcome (relative risk [RR], 4.1, 95% confidence interval [CI], 3.7-4.6) and stillbirth (RR, 8.3, 95% CI, 5.1-13.4). Infants SGA by customized standard only (n = 4015) had an increased risk of adverse neonatal outcome (RR, 2.0, 95% CI, 1.8-2.2) and stillbirth (RR, 3.0, 95% CI, 1.7-5.3). Few infants were identified as SGA by INTERGROWTH-21st only (n = 172), and risks of adverse neonatal outcome and stillbirth were not increased. Findings were unchanged when analyses were limited to term infants (n = 50,739). The INTERGROWTH-21st standard identified more Indian (12.8%) and Asian (5.8%) but fewer European (3.0%) and Pacific (2.9%) infants as SGA (P < .01). Customized criteria identified more than 3 times as many SGA infants among Maori (14.5%), Pacific (13.5%), and European (11.2%) infants and twice as many among Asian (10.3%) infants (P<0.01) compared with INTERGROWTH-21st criteria. The majority of SGA infants by INTERGROWTH-21st only were born to Indian and Asian mothers (95.4%). CONCLUSIONS: In our general obstetric population, birthweight customization identified more SGA infants at risk of perinatal mortality and morbidity compared with the INTERGROWTH-21st standard. The INTERGROWTH-21st standard failed to detect many at-risk SGA infants, particularly among ethnic groups with larger maternal size while disproportionately identifying higher rates of SGA among those with smaller maternal size. Local validation is needed prior to implementation of the INTERGROWTH-21st standard to avoid misclassification of infant birth size.

Ethnic disparities in repeat caesarean rates at Auckland Hospital.

BACKGROUND: New Zealand guidelines recommend that information regarding childbirth choices be given to women with previous caesarean, so they can make informed decisions about their care. We hypothesised that rates of trial of labour (TOL) and vaginal birth after caesarean (VBAC) would vary by women's ethnicity. AIM: To estimate the association of ethnicity with TOL and VBAC rates. MATERIALS AND METHODS: Clinical data were used to identify women who gave birth at Auckland Hospital in 2006-2009 with history of previous caesarean eligible for TOL. Multivariable models were used to estimate the association of women's characteristics (ethnicity, age, socio-economic status (SES), height, body mass index, lead maternity carer, diabetes, hypertension, haemorrhage, labour induction, gestational age) with rates of TOL and VBAC. RESULTS: In the study cohort of 2400 women, the TOL rate was 39.5%; the VBAC rate was 57.4%. Pacific women were twice as likely to have TOL, while Asian and non-New Zealand European women were half as likely to have VBAC, compared with New Zealand European women. Women in more deprived areas were more likely to have TOL, but SES was not associated with VBAC rates. Women under the care of private obstetricians were least likely to have TOL or VBAC. CONCLUSIONS: There are ethnic disparities in TOL and VBAC rates at our hospital. Strategies need to be developed to ensure that women of all ethnicities have access to both options for mode of delivery.

Ethnicity and risk of caesarean section in a term, nulliparous New Zealand obstetric cohort.

BACKGROUND: One in four New Zealand (NZ) women undergo caesarean section (CS); however, little is understood about how ethnicity influences CS rates. Previous NZ studies do not include many of NZ's ethnic groups and have been unable to account comprehensively for clinical risk factors. AIM: To investigate ethnicity as an independent risk factor for elective and emergency CS in nulliparous women at term. We hypothesised that compared with European, Maori and Pacific women would have a lower risk of elective CS, but there would be no ethnic differences in emergency CS. METHODS: This was a retrospective cohort analysis of prospectively recorded maternity data at National Women's Health, Auckland, NZ from 2006 to 2009. The study population was 11 848 singleton, nulliparous, term births. Multivariable logistic regression analysis was performed for elective and emergency CS, accounting for comprehensive confounding factors. RESULTS: The overall CS rate was 31.2% (elective 7.8%, n = 923 and emergency 23.4%, n = 2770). Compared with European ethnicity, Pacific and Chinese women had a reduced odds of elective CS (adjusted odds ratios, aOR 0.42, [95% CI 0.24-0.73] and 0.68, [0.49-0.94], respectively), while Indian women had an increased odds of emergency CS (aOR 1.54, [1.26-1.88]). Rates of elective or emergency CS for other ethnicities were similar to European. CONCLUSIONS: After adjustment for confounding, we report ethnic differences in elective and emergency CS rates, which may be related to patient and/or care provider factors. Further prospective research is recommended to examine reasons for these ethnic differences in CS rates.

Gestational weight gain and adverse pregnancy outcomes in a nulliparous cohort.

OBJECTIVE: Excessive gestational weight gain (GWG) is an important contributing factor to the obesity epidemic in women and is associated with pregnancy complications. We investigated the relationship between GWG and caesarean delivery in labour, large for gestational age (LGA), small for gestational age (SGA) infants and pregnancy-induced hypertension by maternal pre-pregnancy body mass index (BMI) in a contemporary nulliparous cohort. STUDY DESIGN: Using 2009 Institute of Medicine guidelines, participants in the SCOPE study (from Cork, Ireland, Auckland, New Zealand and Adelaide, Australia) were classified into GWG categories (low, normal and high) according to pre-pregnancy BMI. Maternal characteristics and pregnancy outcomes were compared between weight gain categories. SGA and LGA were defined as <10th and >90th customised birthweight centile. Multivariable analysis adjusted for confounding factors that impact on GWG including BMI. RESULTS: Of 1950 participants, 17.2% (n=335) achieved the recommended GWG, 8.6% (n=167) had low and 74.3% (n=1448) had high GWG. Women with high GWG had increased rates of LGA infants [adjusted OR 4.45 (95% CI 2.49-7.99)] and caesarean delivery in labour [aOR 1.46 (1.03-2.07)]. SGA was increased in women with low GWG [aOR 1.79 (1.06-3.00)]. CONCLUSION: Three quarters of participants had high GWG, which was associated with an independent risk of LGA infants and caesarean in labour. Low GWG was associated with SGA infants. These adverse outcomes are potentially modifiable by achievement of normal GWG, which should be an important focus of antenatal care.