Béatrice Blondel

Abstract: Background. Existing fetal growth references all suffer from 1 or more major methodologic problems, including errors in reported gestational age, biologically implausible birth weight for gestational age, insufficient sample sizes at low gestational age, single-hospital or other non-population–based samples, and inadequate statistical modeling techniques. Methods. We used the newly developed Canadian national linked file of singleton births and infant deaths for births between 1994 and 1996, for which gestational age is largely based on early ultrasound estimates. Assuming a normal distribution for birth weight at each gestational age, we used the expectation-maximization algorithm to exclude infants with gestational ages that were more consistent with 40-week births than with the observed gestational age. Distributions of birth weight at the corrected gestational ages were then statistically smoothed. Results. The resulting male and female curves provide smooth and biologically plausible means, standard deviations, and percentile cutoffs for defining small- and large-for-gestational-age births. Large-for-gestational age cutoffs (90th percentile) at low gestational ages are considerably lower than those of existing references, whereas small-for-gestational-age cutoffs (10th percentile) postterm are higher. For example, compared with the current World Health Organization reference from California (Williams et al, 1982) and a recently proposed US national reference (Alexander et al, 1996), the 90th percentiles for singleton males at 30 weeks are 1837 versus 2159 and 2710 g. The corresponding 10th percentiles at 42 weeks are 3233 versus 3086 and 2998 g. Conclusions. This new sex-specific, population-based reference should improve clinical assessment of growth in individual newborns, population-based surveillance of geographic and temporal trends in birth weight for gestational age, and evaluation of clinical or public health interventions to enhance fetal growth. fetal growth, birth weight, gestational age, preterm birth, postterm birth.

Abstract: After a substantial decrease in the middle of the 20th century, multiple pregnancy rates have increased in many Western countries. Between the mid-1970s and 1998, the rate of twin pregnancies increased by 50% to 60% in England and Wales, France, and the United States. The rates of triplet or higher-order multiple pregnancies increased by 310% in France, 430% in England and Wales, and 696% in the United States. One fourth to one third of the increase in twin or triplet pregnancies are attributable to a contemporaneous increase in maternal age. Furthermore, in countries with high occurrence of multiple births, 30% to 50% of twin pregnancies and at least 75% of triplet pregnancies occur after infertility treatment. The impact of the increase in multiple births on preterm delivery rates in the overall population is mainly attributable to twin pregnancies. In Canada, France, and the United States, an increase in preterm births among multiples contributed almost as much as the increase in occurrence of multiple births to the increase or stabilization of the overall rates of preterm delivery observed in these countries.

Abstract: Objective To investigate time trends in preterm birth in Europe by multiplicity, gestational age, and onset of delivery. Design Analysis of aggregate data from routine sources. Setting Nineteen European countries. Population Live births in 1996, 2000, 2004, and 2008. Methods Annual risk ratios of preterm birth in each country were estimated with year as a continuous variable for all births and by subgroup using log-binomial regression models. Main outcome measures Overall preterm birth rate and rate by multiplicity, gestational age group, and spontaneous versus non-spontaneous (induced or prelabour caesarean section) onset of labour. Results Preterm birth rates rose in most countries, but the magnitude of these increases varied. Rises in the multiple birth rate as well as in the preterm birth rate for multiple births contributed to increases in the overall preterm birth rate. About half of countries experienced no change or decreases in the rates of singleton preterm birth. Where preterm birth rates rose, increases were no more prominent at 35-36 weeks of gestation than at 32-34 weeks of gestation. Variable trends were observed for spontaneous and non-spontaneous preterm births in the 13 countries with mode of onset data; increases were not solely attributed to non-spontaneous preterm births. Conclusions There was a wide variation in preterm birth trends in European countries. Many countries maintained or reduced rates of singleton preterm birth over the past 15 years, challenging a widespread belief that rising rates are the norm. Understanding these cross-country differences could inform strategies for the prevention of preterm birth. © 2013 The Authors. BJOG: An International Journal of Obstetrics & Gynaecology published by John Wiley and Sons on behalf of the Royal College of Obstetricians and Gynaecologists.

Abstract: OBJECTIVE: To study trends in the main indicators of health, medical practices and risk factors in France. POPULATION AND METHOD: We collected data from samples of all births in France during one week in 1995 (n=13318), 1998 (n=13718), 2003 (n=14737) and 2010 (n=14903) and have compared them. RESULTS: Between 1995 and 2010, maternal age and body mass index increased steadily, but tobacco use decreased. In 2010, 39.4% of pregnant women had a visit with a midwife in a maternity unit, versus 26.6% in 2003. Deliveries occurred in large public hospitals more and more frequently. The increase in caesarean sections was no longer significant between 2003 and 2010. In general, medical decisions during pregnancy and delivery were closer to professional recommendations in 2010 than in earlier years. Live births before 37 weeks increased steadily from 5.4% in 1995 to 6.6% in 2010, but the proportion of birth weights below 2500g or the 10th percentile stopped increasing after 2003. CONCLUSION: Routine national perinatal surveys highlight major trends in maternal characteristics, obstetric practices, organisation of services, and perinatal health.

Abstract: Journal de Gynecologie Obstetrique et Biologie de la Reproduction - Vol. 35 - N° 4 - p. 373-387

Abstract: Summary The importance of breastfeeding in low-income and middle-income countries is well recognised, but less consensus exists about its importance in high-income countries. In low-income and middle-income countries, only 37% of children younger than 6 months of age are exclusively breastfed. With few exceptions, breastfeeding duration is shorter in high-income countries than in those that are resource-poor. Our meta-analyses indicate protection against child infections and malocclusion, increases in intelligence, and probable reductions in overweight and diabetes. We did not find associations with allergic disorders such as asthma or with blood pressure or cholesterol, and we noted an increase in tooth decay with longer periods of breastfeeding. For nursing women, breastfeeding gave protection against breast cancer and it improved birth spacing, and it might also protect against ovarian cancer and type 2 diabetes. The scaling up of breastfeeding to a near universal level could prevent 823 000 annual deaths in children younger than 5 years and 20 000 annual deaths from breast cancer. Recent epidemiological and biological findings from during the past decade expand on the known benefits of breastfeeding for women and children, whether they are rich or poor.

Abstract: Summary Background Preterm birth is the second largest direct cause of child deaths in children younger than 5 years. Yet, data regarding preterm birth ( Methods We assessed various data sources according to prespecified inclusion criteria. National Registries (563 datapoints, 51 countries), Reproductive Health Surveys (13 datapoints, eight countries), and studies identified through systematic searches and unpublished data (162 datapoints, 40 countries) were included. 55 countries submitted additional data during WHO's country consultation process. For 13 countries with adequate quality and quantity of data, we estimated preterm birth rates using country-level loess regression for 2010. For 171 countries, two regional multilevel statistical models were developed to estimate preterm birth rates for 2010. We estimated time trends from 1990 to 2010 for 65 countries with reliable time trend data and more than 10 000 livebirths per year. We calculated uncertainty ranges for all countries. Findings In 2010, an estimated 14·9 million babies (uncertainty range 12·3–18·1 million) were born preterm, 11·1% of all livebirths worldwide, ranging from about 5% in several European countries to 18% in some African countries. More than 60% of preterm babies were born in south Asia and sub-Saharan Africa, where 52% of the global livebirths occur. Preterm birth also affects rich countries, for example, USA has high rates and is one of the ten countries with the highest numbers of preterm births. Of the 65 countries with estimated time trends, only three (Croatia, Ecuador, and Estonia), had reduced preterm birth rates 1990–2010. Interpretation The burden of preterm birth is substantial and is increasing in those regions with reliable data. Improved recording of all pregnancy outcomes and standard application of preterm definitions is important. We recommend the addition of a data-quality indicator of the per cent of all live preterm births that are under 28 weeks' gestation. Distinguishing preterm births that are spontaneous from those that are provider-initiated is important to monitor trends associated with increased caesarean sections. Rapid scale up of basic interventions could accelerate progress towards Millennium Development Goal 4 for child survival and beyond. Funding Bill & Melinda Gates Foundation through grants to Child Health Epidemiology Reference Group (CHERG) and Save the Children's Saving Newborn Lives programme; March of Dimes; the Partnership for Maternal Newborn and Childe Health; and WHO, Department of Reproductive Health and Research.

Abstract: Resumen Incidencia mundial de parto prematuro: revision sistematica de la morbilidad y mortalidad maternas Objetivo Analizar las tasas de prematuridad a nivel mundial para evaluar la incidencia de este problema de salud publica, determinar la distribucion regional de los partos prematuros y profundizar en el conocimiento de las actuales estrategias de evaluacion.Metodos Los datos utilizados sobre las tasas de prematuridad a nivel mundial se extrajeron a lo largo de una revision sistematica anterior de datos publicados e ineditos sobre la mortalidad y morbilidad maternas notificados entre 1997 y 2002. Esos datos se complementaron mediante una busqueda que abarco el periodo 2003–2007. Las tasas de prematuridad de los paises sin datos se estimaron mediante modelos de regresion multiple especificos para cada region.Resultados Estimamos que en 2005 se registraron 12,9 millones de partos prematuros, lo que representa el 9,6% de todos los nacimientos a nivel mundial. Aproximadamente 11 millones (85%) de ellos se concentraron en Africa y Asia, mientras que en Europa y America del Norte (excluido Mexico) se registraron 0,5 millones en cada caso, y en America Latina y el Caribe, 0,9 millones. Las tasas mas elevadas de prematuridad se dieron en Africa y America del Norte (11,9% y 10,6% de todos los nacimientos, respectivamente), y las mas bajas en Europa (6,2%).Conclusion El parto prematuro es un problema de salud perinatal importante en todo el mundo. Los paises en desarrollo, especialmente de Africa y Asia meridional, son los que sufren la carga mas alta en terminos absolutos, pero en America del Norte tambien se observa una tasa elevada. Es necesario comprender mejor las causas de la prematuridad y obtener estimaciones mas precisas de la incidencia de ese problema en cada pais si se desea mejorar el acceso a una atencion obstetrica y neonatal eficaz.

Abstract: Introduction Preterm birth, defined as childbirth occurring at less than 37 completed weeks or 259 days of gestation, is a major determinant of neonatal mortality and morbidity and has long-term adverse consequences for health. (1-3) Children who are born prematurely have higher rates of cerebral palsy, sensory deficits, learning disabilities and respiratory illnesses compared with children born at term. The morbidity associated with preterm birth often extends to later life, resulting in enormous physical, psychological and economic costs. (4,5) Estimates indicate that in 2005 the costs to the United States of America alone in terms of medical and educational expenditure and lost productivity associated with preterm birth were more than USS 26.2 billion. (6) Of all early neonatal deaths (deaths within the first 7 days of life) that are not related to congenital malformations, 28% are due to preterm birth. (7) Preterm birth rates have been reported to range from 5% to 7% of live births in some developed countries, but are estimated to be substantially higher in developing countries. (8) These figures appear to be on the rise. (9) Events leading to preterm birth are still not completely understood, although the etiology is thought to be multifactorial. It is, however, unclear whether preterm birth results from the interaction of several pathways or the independent effect of each pathway. Causal factors linked to preterm birth include medical conditions of the mother or fetus, genetic influences, environmental exposure, infertility treatments, behavioural and socioeconomic factors and iatrogenic prematurity. (9) Approximately 45-50% of preterm births are idiopathic, 30% are related to preterm rupture of membranes (PROM) and another 15-20% are attributed to medically indicated or elective preterm deliveries. (10,11) Estimation of preterm birth rates and, ideally, their proper categorization (e.g. spontaneous versus indicated) are essential for accurate determination of global incidence in order to inform policy and programmes on interventions to reduce the risk of premature labour and delivery. No data have been published on the global incidence of preterm birth. Preterm birth rates available from some developed countries, such as the United Kingdom, the United States and the Scandinavian countries, show a dramatic rise over the past 20 years. (6,12) Factors possibly contributing to but not completely explaining this upward trend include increasing rates of multiple births, greater use of assisted reproduction techniques, increases in the proportion of births among women over 34 years of age and changes in clinical practices, such as greater use of elective Caesarean section. For example, the increasing use of ultrasonography rather than the date of the last menstrual period to estimate gestational age may have resulted in larger numbers of births being classified as preterm. Changes in the definitions of fetal loss, stillbirth and early neonatal death may also have contributed to the substantial increases in preterm birth rates recorded in developed countries in the past two decades. (13,14) In developing countries, accurate and complete population data and medical records usually do not exist. Furthermore, estimates of the rate of preterm birth in developing countries are influenced by a range of factors including varying procedures used to determine gestational age, national differences in birth registration processes, heterogeneous definitions used for preterm birth, differences in perceptions of the viability of preterm infants and variations in religious practices such as local burial customs, which can discourage the registering of preterm births. (15) These issues make measurement of preterm birth and comparisons across and between developing countries difficult. The World Health Organization (WHO) conducted a systematic review of the worldwide incidence/prevalence of maternal mortality and morbidity in the period 1997-2002 to contribute to the knowledge base in this area. …