International Collaborative Effort (ICE) on birthweight; plurality; and perinatal and infant mortality. II: Comparisons between birthweight distributions of births in member countries from 1970 to 1984

Member states of the International and Collaborative Effort (ICE) are the United States of America, England and Wales, Denmark, Bavaria and North Rhine-Westphalia of the Federal Republic of Germany, Israel, Japan, Norway, Scotland and Sweden. The group has collected, analysed and compared distributions of birthweight for member countries, where available from 1970 onwards, for singleton and all livebirths, stillbirths, early and late neonatal and postneonatal deaths. The present paper is an account of the differences in birthweight distributions, and trends over time seen between and within countries, for livebirths and stillbirths. The major findings are the relative robustness over time of the parameters which characterize the distribution of birthweight within countries, and the marked and consistent differences between these distributions in different countries.     

A routine system for monitoring perinatal deaths in Scotland

Since 1983 the monitoring of perinatal deaths in Scotland has been incorporated into the established data collection system which monitors maternal and child health in Scotland. This paper describes the transition from a research project to the routine system and the extension of the data collection to include paediatric and pathological findings. This information is provided by local co-ordinators in active clinical practice. Baseline data are obtained from the routine maternity discharge document (SMR 2). A summary of the findings for the first 4 years of the study, 1977, 1979, 1980 and 1981 is presented, including information about birthweight and gestation-specific perinatal mortality rates; perinatal mortality rates by time of death in relation to labour and singleton and multiple perinatal mortality rates by the obstetric complication preceding the death.     

A routine system for monitoring perinatal deaths in Scotland

Summary. Since 1983 the monitoring of perinatal deaths in Scotland has been incorporated into the established data collection system which monitors maternal and child health in Scotland. This paper describes the transition from a research project to the routine system and the extension of the data collection to include paediatric and pathological findings. This information is provided by local co-ordinators in active clinical practice. Baseline data are obtained from the routine maternity discharge document (SMR 2). A summary of the findings for the first 4 years of the study, 1977, 1979, 1980 and 1981 is presented, including information about birthweight and gestation-specific perinatal mortality rates; perinatal mortality rates by time of death in relation to labour and singleton and multiple perinatal mortality rates by the obstetric complication preceding the death.     

Pregnancy-related deaths in four regions of Europe and the United States in 1999-2000: characterisation of unreported deaths

OBJECTIVE: We compared official maternal mortality statistics with those from a special study covering all pregnancy-associated deaths in two European countries (Finland and France) and in two US states (Massachusetts and North Carolina) in 1999-2000 to characterize pregnancy-related deaths that are not included in official statistics. STUDY DESIGN: We linked the official ICD-10-based maternal mortality data for 84 deaths with study data on 404 pregnancy-associated deaths. RESULTS: Of the pregnancy-associated deaths, 151 were pregnancy-related. We found 69 pregnancy-related deaths that had not been included as maternal deaths, and two deaths coded as maternal deaths that did not meet our definition for a pregnancy-related death. In total, 58 of these 69 deaths were from medical causes and 11 were from external causes or injuries (10 postpartum depression-related suicides and one accidental drug poisoning). The unreported deaths due to medical causes included 27 direct, 15 indirect, and two direct/indirect pregnancy-related deaths and 14 possibly pregnancy-related deaths. The most common causes of the unreported deaths due to medical causes were intracerebral hemorrhage (7 deaths), peripartum cardiomyopathy (4), pulmonary embolism (4) and pregnancy-induced hypertension (4). CONCLUSIONS: The collection of data on pregnancy-related and pregnancy-associated deaths is useful for countries with low maternal mortality figures. The use of various data-collection methods may substantially increase the quality of maternal mortality statistics.     

Birthweight by gestational age and sex at a rural referral center.

OBJECTIVE: Determine the distribution of birthweights in singleton births by gestational age and gender at Marquette General Hospital, a rural referral center in Michigan's upper peninsula. STUDY DESIGN: Birth log data were examined for prenatal factors and obstetrical outcomes. The birthweight distribution was compared to published values, and a linear regression model of prenatal factors was developed. RESULTS: Our median birthweights were significantly greater than published values. Males were 128 g heavier than female infants after adjusting for gestational age. In a multivariable linear regression model, birthweight was significantly associated with gestational age, sex of the infant, maternal age, primigravida status of mother, and maternal diabetes (all p<0.01). Using published standards resulted in an overdiagnosis of large for gestational age and an underdiagnosis of small for gestational age. CONCLUSION: Local birthweight distributions can differ significantly from historical or national distributions. The development of birthweight distributions accommodating for prenatal factors is needed.     

Global and regional estimates of preeclampsia and eclampsia: a systematic review

Reduction of maternal mortality is a target within the Millennium Development Goals. Data on the incidence of preeclampsia and eclampsia, one of the main causes of maternal deaths, are required at both national and regional levels to inform policies. We conducted a systematic review of the incidence of hypertensive disorders of pregnancy (HDP) with the objective of evaluating its magnitude globally and in different regions and settings. We selected studies using pre-specified criteria, recorded database characteristics and assessed methodological quality of the eligible studies reporting incidence of any HDP during the period 2002–2010. A logistic model was then developed to estimate the global and regional incidence of HDP using pre-specified predictor variables where empiric data were not available. We found 129 studies meeting the inclusion criteria, from which 74 reports with 78 datasets reporting HDP were analysed. This represents nearly 39 million women from 40 countries. When the model was applied, the overall estimates are 4.6% (95% uncertainty range 2.7–8.2), and 1.4% (95% uncertainty range 1.0–2.0) of all deliveries for preeclampsia and eclampsia respectively, with a wide variation across regions. The figures we obtained give a general idea of the magnitude of the problem and suggest that some regional variations might exist. The absence of data in many countries is of concern, however, and efforts should be made to implement data collection and reporting for substantial statistics. The implementation of large scale surveys conducted during a short period of time could provide more reliable and up-to-date estimations to inform policy.     

3.6 million neonatal deaths--what is progressing and what is not?

Each year 3.6 million infants are estimated to die in the first 4 weeks of life (neonatal period)--but the majority continue to die at home, uncounted. This article reviews progress for newborn health globally, with a focus on the countries in which most deaths occur--what data do we have to guide accelerated efforts? All regions are advancing, but the level of decrease in neonatal mortality differs by region, country, and within countries. Progress also differs by the main causes of neonatal death. Three major causes of neonatal deaths (infections, complications of preterm birth, and intrapartum-related neonatal deaths or "birth asphyxia") account for more than 80% of all neonatal deaths globally. The most rapid reductions have been made in reducing neonatal tetanus, and there has been apparent progress towards reducing neonatal infections. Limited, if any, reduction has been made in reducing global deaths from preterm birth and for intrapartum-related neonatal deaths. High-impact, feasible interventions to address these 3 causes are summarized in this article, along with estimates of potential for lives saved. A major gap is reaching mothers and babies at birth and in the early postnatal period. There are promising community-based service delivery models that have been tested mainly in research studies in Asia that are now being adapted and evaluated at scale and also being tested through a network of African implementation research trials. To meet Millennium Development Goal 4, more can and must be done to address neonatal deaths. A critical step is improving the quantity, quality and use of data to select and implement the most effective interventions and strengthen existing programs, especially at district level.     

Birthweight-specific neonatal mortality in developing countries and obstetric practices.

OBJECTIVES: To evaluate birthweight-specific neonatal mortality and perinatal interventions in major medical centers in developed and developing countries. METHODS: A survey was developed and electronically mailed to 13 medical centers participating in the Global Network for Perinatal and Reproductive Health (GNPRH). The ability of a center to provide requested data was assessed. The mortality rates and use of specific perinatal interventions in centers in developing countries were compared with developed countries. RESULTS: Nine centers in developing countries responded to the survey, and three centers in developed countries were used for comparison. Data collection was highly variable. Most developing country centers were able to provide data by birthweight but not by gestational age. The differences in mortality rates between developing and developed countries were more pronounced at lower gestational ages and birthweights. A difference was found in perinatal interventions between developing and developed countries. In the former, viability was generally considered 28 weeks, and the gestational age at which cesarean sections were usually performed for the sake of the fetus at preterm gestations varied from 26 to 37 weeks. Most centers did not routinely induce for pPROM; only five out of nine centers used antibiotics to prolong latency. Most centers used tocolysis beginning at 26-28 weeks through 32-37 weeks, and a variety of tocolytic agents were used. Most centers routinely used corticosteroids for preterm infants, and all centers employed repeat weekly steroid dosing if undelivered. CONCLUSIONS: Despite the fact that the GNPRH centers included in this study represent some of the best health care available in these countries, they lag far behind centers in developed countries in neonatal mortality rates and their use of various obstetric practices. Furthermore, incomplete and inconsistent data collection complicates the evaluation of the factors contributing to high neonatal mortality rates.     

Mode of delivery and neonatal death in 17,587 infants presenting by the breech

OBJECTIVE--To study the effects of caesarean section on neonatal mortality in infants presenting by the breech. DESIGN--Population-based non-experimental comparison of infants presenting by the breech born vaginally with those born by caesarean section. Neonatal mortality rates were calculated for 250 g birthweight intervals. Weight-specific relative risks (RRs) were further adjusted for birthweight in 50 g categories. SETTING--New York City, 1978-1983. Data came from the Department of Health's computerized vital records on livebirths and infant deaths. SUBJECTS--17,587 singleton breech livebirths greater than or equal to 500 g birthweight, with congenital anomaly deaths excluded. 6178 were born vaginally and 11409 were born by caesarean section. MAIN OUTCOME MEASURES--Birthweight-specific and birthweight-adjusted neonatal mortality. RESULTS--At birthweights of 501 to 1750 g, the risk of neonatal death for breech infants born vaginally was significantly higher than the risk for those born by caesarean section (weight-adjusted RR = 1.7). For breech infants with birthweights over 3000 g, the weight-adjusted risk was 5.6 times greater for a vaginal birth compared with caesarean section. The addition of 16 additional control variables in multiple logistic regression analyses did not change these RRs. CONCLUSION--Population-based studies indicate that an increase in the caesarean section rate among breech singletons may be associated with increased neonatal survival, but a large multicentre randomized trial of management of breech presentation would answer the question much more definitively.     

Different policies on prenatal ultrasound screening programmes and induced abortions explain regional variations in infant mortality with congenital malformations

OBJECTIVE: To compare the impact of induced abortions (IA) on the mortality of infants with congenital malformations in four European regions with different policies on IA and prenatal ultrasound screening for congenital malformations. METHODS: A registry-based collection of data on congenital malformations in four different countries: Ireland (Dublin), Denmark (Funen County), Austria (Styria), and France (Strasbourg). RESULTS: The proportion of infant deaths with malformations ranged from 23 to 44% of all infant deaths with the highest proportion in Dublin, where IA is not allowed and prenatal ultrasound screening not performed. There were highly significant differences in the prevalences of IA (p < 0.001), fetal deaths (p < 0.01), and deaths in infants with congenital malformations (p < 0.001) between the four regions. The differences in total mortality with congenital malformations (IA + fetal deaths + infant deaths) between regions decreased, and only Strasbourg differs significantly from the other three regions. CONCLUSION: Prenatal ultrasound screening programmes have only a minor impact on total mortality with congenital malformations from 2nd trimester of pregnancy to 1 year of age, but seem to change the time of death which may be important for both the parents and the community.     

Mortality in relation to method of delivery in breech infants

To study the relation of method of delivery to perinatal mortality, we examined information from the deliveries of 1593 breech infants weighing 1000 g or more born in 1976 and 1977. In none of the birthweight groups 1000 g or more was neonatal mortality significantly different between infants delivered vaginally compared with those delivered by cesarean section, although the number of deaths was small. In all the birthweight groups, perinatal mortality was higher in breeches delivered vaginally, but the differences were because all of the infants who died before labor were delivered vaginally. Total mortality (intrapartum plus neonatal deaths) in infants who survived to labor was not significantly different in breech infants delivered by one or the other method at any birthweight. These data suggest that routine cesarean delivery for infants 1000 g or more who are in the breech presentation may not be justified from the standpoint of mortality.     

A multi-country study of the “intrapartum stillbirth and early neonatal death indicator” in hospitals in low-resource settings

Objective

To determine the feasibility of introducing a simple indicator of quality of obstetric and neonatal care and to determine the proportion of potentially avoidable perinatal deaths in hospitals in low-income countries.

Methods

Between September 1, 2011, and February 29, 2012, data were collected from consecutive women who were admitted to the labor ward of 1 of 6 hospitals in 4 low-income countries. Fetal heart tones on admission were monitored, and demographic and birth data were recorded.

Results

Data were obtained for 3555 women and 3593 neonates (including twins). The doptone was used on 97% of women admitted. The overall perinatal mortality rate was 34 deaths per 1000 deliveries. Of the perinatal deaths, 40%–45% occurred in the hospital and were potentially preventable by better hospital care.

Conclusion

The results demonstrated that it is possible to accurately determine fetal viability on admission via a doptone. Implementation of doptone use, coupled with a concise data record, might form the basis of a low-cost and sustainable program to monitor and evaluate efforts to improve quality of care and ultimately might help to reduce the in-hospital component of perinatal mortality in low-income countries.     

Classification of perinatal and late neonatal deaths in Iceland. A survey from a defined population

A retrospective case record analysis of all perinatal and late neonatal deaths in Iceland in the periods 1976-80 and 1981-85 was done and the causes of death classified according to the extended Aberdeen classification. There was a significant (p less than 0.0001) reduction in number of deaths between the two periods with perinatal mortality rates declining from 10.6/1000 in 1976-80 to 6.8/1000 in 1981-85. In 1976-80 there were 81 (33%) antepartum, 37 (15%) intrapartum and 128 (52%) neonatal deaths compared to 61 (38%) antepartum, 13 (8%) intrapartum and 86 (54%) neonatal deaths in 1981-85. Fetal abnormality was the most common cause of death in both periods followed by the category Low birthweight in 1976-80. In 1981-85 increased morphological detection of infection in infants of very low birthweight by placental examination and autopsies lead to a shift from the category Low birthweight to Maternal Disease, the second most common cause in that period. To achieve lower perinatal mortality rates efforts should be directed towards lowering antepartum losses near term and increasing survival of very low birthweight infants.     

Customised birthweight: coefficients for an Australian population and validation of the model

BACKGROUND: Published birthweight references in Australia do not fully take into account constitutional factors that influence birthweight and therefore may not provide an accurate reference to identify the infant with abnormal growth. Furthermore, studies in other regions that have derived adjusted (customised) birthweight references have applied untested assumptions in the statistical modelling. AIMS: To validate the customised birthweight model and to produce a reference set of coefficients for estimating a customised birthweight that may be useful for maternity care in Australia and for future research. METHODS: De-identified data were extracted from the clinical database for all births at the Mater Mother's Hospital, Brisbane, Australia, between January 1997 and June 2005. Births with missing data for the variables under study were excluded. In addition the following were excluded: multiple pregnancies, births less than 37 completed week's gestation, stillbirths, and major congenital abnormalities. Multivariate analysis was undertaken. A double cross-validation procedure was used to validate the model. RESULTS: The study of 42,206 births demonstrated that, for statistical purposes, birthweight is normally distributed. Coefficients for the derivation of customised birthweight in an Australian population were developed and the statistical model is demonstrably robust. CONCLUSIONS: This study provides empirical data as to the robustness of the model to determine customised birthweight. Further research is required to define where normal physiology ends and pathology begins, and which segments of the population should be included in the construction of a customised birthweight standard.     

Variation in rates of postterm birth in Europe: reality or artefact?

Objective  To compare rates of postterm birth in Europe.
Design  Analysis of data from vital statistics, birth registers, and national birth samples collected for the PERISTAT project.
Setting  Thirteen European countries.
Population  All live births or representative samples of births for the year 2000 or most recent year available.
Methods  Comparison of national and regional rates of postterm birth. Other indicators (birthweight, deliveries with a non-spontaneous onset and mortality) were used to assess the validity of postterm rates.
Main outcome measures  The proportion of births at 42 completed weeks of gestation or later.
Results  Postterm rates varied greatly, from 0.4% (Austria, Belgium) to over 7% (Denmark, Sweden) of births. Higher postterm rates were associated with a greater proportion of babies with birthweight 4500 g or more. Fetal and early neonatal mortality rates were higher among postterm births than among births at 40 weeks. Countries with higher proportions of births with a nonspontaneous onset of labour had lower postterm birth rates. The shapes of the gestational-age distributions at term varied. In some countries, there was a sharp cutoff in deliveries at 40 weeks, while elsewhere this occurred at 41 weeks.
Conclusions  These results suggest that practices for managing pregnancies continuing beyond term differ in Europe and raise questions about the health and other impacts in countries with markedly high or low postterm rates. Some variability in these rates may also be due to methods for determining gestational age, which has broader implications for international comparisons of gestational age, including rates of postterm and preterm births and small-for-gestational-age newborns.     

Can a developed country’s maternal mortality review be used as the ‘gold standard’ for a developing country?

Background: Relative to other public health problems, maternal mortality ratio (MMR) differences between developed and developing countries are greater than expected. South Africa (SA) produced its first national report on maternal deaths in 1998. UK’s last report covered the period 1994–1996. Objective and Method: Compare the two reports to document reasons for the MMR differences using the Safe Motherhood analytical model of maternal mortality as a template. Results: The MMR for SA was estimated to be 12.3 times greater than the UK’s. Under-reporting was bigger in SA. Substandard medical care was common, but other quality of care issues were not assessed. Disease pattern differences included AIDS, non-pregnancy-related infections and postpartum haemorrhage in SA compared to thromboembolism and medical disorders in the UK. Autopsies were problematic. Demographic differences centred around ethnic origins. Biological differences may involve the immune system. Socio-economic or behavioural factors were not documented. Conclusions: Awareness of the magnitude of the problem requires better data collection systems. Sepsis and HIV/AIDS are a major problem in SA. Beyond the mutually common problem of substandard medical care, other quality of care issues were inadequately assessed.     

The association of ambient outdoor temperature throughout pregnancy and offspring birthweight: findings from the Aberdeen Children of the 1950s cohort

BACKGROUND: We assessed the effect of mean ambient outdoor temperature during gestation on birthweight. OBJECTIVE: To assess the effect of mean ambient outdoor temperature during gestation on birth weight. DESIGN: Birth cohort study with record linkage to climate databases. SETTING: Aberdeen, Scotland. SAMPLE: A total of 12,150 individuals born in Aberdeen, Scotland between 1950 and 1956. METHODOLOGY/PRINCIPAL FINDINGS: Perinatal data from a cohort of 12,150 individuals born in Aberdeen, Scotland between 1950 and 1956 were linked to daily outdoor temperature data. Birthweight was seasonally patterned, with lowest birthweights among those born in the winter months (December-February) and highest birthweights among those born in the autumn months (September-November); P= 0.01 for joint sine-cosine functions. Mean ambient outdoor temperature during the first trimester of pregnancy was inversely associated with birthweight and mean ambient outdoor temperature during the third trimester of pregnancy was positively associated with birthweight. In fully adjusted (for sex, maternal age, birth year, birth order and social class) models a 1 degrees C increase in mean ambient outdoor temperature in the mid 10-day period of the first trimester was associated with a 5.4-g (95% confidence interval [CI] 2.9, 7.9 g) decrease in birthweight, whereas a 1 degrees C increase in the mid 10-day period of the third trimester was associated with a 1.3-g (95% CI 0.50, 2.1 g) increase in birthweight. Ambient outdoor temperature in the first trimester of pregnancy explained the seasonal patterning of birthweight. MAIN OUTCOME MEASURE: Birthweight. RESULTS: Birthweight was seasonally patterned, with lowest birthweights among those born in the winter months (December-February) and highest birthweights among those born in the autumn months (September-November); P= 0.01 for joint sine-cosine functions. Mean ambient outdoor temperature during the first trimester of pregnancy was inversely associated with birthweight and mean ambient outdoor temperature during the third trimester of pregnancy was positively associated with birthweight. In fully adjusted (for sex, maternal age, birth year, birth order and social class) models a 1 degrees C increase in mean ambient outdoor temperature in the mid 10-day period of the first trimester was associated with a 5.4 g (95% confidence interval 2.9, 7.9 g) decrease in birthweight, whereas a 1 degrees C increase in the mid 10-day period of the third trimester was associated with a 1.3 g (95% confidence interval 0.50, 2.1 g) increase in birthweight. Ambient outdoor temperature in the first trimester of pregnancy explained the seasonal patterning of birthweight. CONCLUSION: Higher ambient outdoor temperature in the first trimester of pregnancy and/or lower ambient outdoor temperature in the third trimester are associated with reduced offspring birthweight. With the increasing occurrence of temperature extremes, in particular, heat waves, these findings, if replicated in other studies, have important public health implications.     

Changing problems and priorities in obstetrics

Summary. National perinatal mortality data suggest that the root causes of many deaths may lie in the environmental circumstances in which the mother grew up. Aberdeen primigravidae under the age of 20 years who gave birth to a baby with a birthweight of <2500 g between 1968 and 1972 were divided into those where there was an associated obstetric complication and those where the cause of the low birthweight infant was 'unexplained'. The 'unexplained' group were more often smaller, underweight, cigarette smokers, and from relatively large families in the lower socioeconomic classes. Investigations of case records and by interview revealed that the mothers of these primigravidae were similarly disadvantaged and it is argued that further improvement in perinatal health and mortality will depend on the elimination of this continuity of social disadvantage.     

Neonatal mortality amongst Scottish preterm singleton births (1985–1994)

Objective To provide a valid estimate of singleton neonatal mortality based on birthweight and gestational age at delivery.
Design Record linkage of maternity data and neonatal mortality data.
Setting Scotland, UK.
Population All singleton preterm deliveries from 24 to 36 weeks inclusive between 1985 and 1994.
Main outcome measure Neonatal death.
Results There were 625,646 liveborn singleton deliveries over the study period, of which 33,912 were preterm (5.4%). The overall neonatal mortality in the preterm group was 41/1000 and the data have been presented by both gestational age and birthweight. The neonatal mortality rate fell with advancing gestation from 795/1000 live births at 24 weeks to 9/1000 live births at 36 weeks and was higher at the extremes of birthweight for a given gestational age. There was a significant increase in the proportion of babies delivered iatrogenically over the study period (χ test for trend   P < 0.001  ).
Conclusion This is the largest recent series to consider neonatal mortality using both birthweight and gestational age. These figures will be of use in obstetric management when elective preterm delivery is considered, and for providing prognostic guidance following preterm delivery.