Temporal Trends of Preterm Birth Subtypes and Neonatal Outcomes

Universidad Pontificia Bolivariana, Medellín, Antioquia, Colombia
Obstetrics and Gynecology (Impact Factor: 5.18). 06/2006; 107(5):1035-41. DOI: 10.1097/01.AOG.0000215984.36989.5e
Source: PubMed


To describe temporal trends of preterm birth subtypes, neonatal morbidity, and hospital neonatal mortality.
A database of 1.7 million births that occurred in 51 maternity hospitals in Latin America from 1985 to 2003 was studied. Subgroups of preterm births were classified according to the presence or absence of maternal medical or obstetric complications, spontaneous labor, preterm labor after premature rupture of membranes, induction of labor, or elective cesarean. Outcomes studied, for different periods, were prevalence of small for gestational age, neonatal morbidity, and neonatal mortality.
Spontaneous preterm labor without maternal complications was the most frequent subtype of preterm birth (60%), followed by premature rupture of membranes without maternal complications. Preterm births due to elective induction and delivery by elective cesarean increased markedly in the last 20 years, from 10% in 1985-1990 to 18.5% in recent years. Neonates born after spontaneous labor without maternal complications had the lowest mortality rate, but their large numbers made them responsible for one half of the preterm mortality. The induction followed by elective cesarean subgroups accounted for 13.4% of the preterm deaths between 1985 and 1990 and increased to 21.2% between 1996 and 2003.
Spontaneous labor in mothers without maternal complications is the most frequent cause of preterm births and is also the most important subgroup related to neonatal mortality. However, preterm births due to induction of labor or elective cesarean are increasing in Latin America and are becoming important contributors to neonatal mortality.

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    • "No population-based studies are available from low- or middle-income countries. However, of the babies born preterm in tertiary facilities in low- and middle-income countries, the reported proportion of preterm births that were provider-initiated ranged from around 20% in Sudan and Thailand to nearly 40% in 51 facilities in Latin America and a teaching hospital in Ghana [48-51]. However, provider-initiated preterm births will represent a relatively smaller proportion of all preterm births in these countries where access to diagnostic tools is limited. "
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    ABSTRACT: This second paper in the Born Too Soon supplement presents a review of the epidemiology of preterm birth, and its burden globally, including priorities for action to improve the data. Worldwide an estimated 11.1% of all livebirths in 2010 were born preterm (14.9 million babies born before 37 weeks of gestation), with preterm birth rates increasing in most countries with reliable trend data. Direct complications of preterm birth account for one million deaths each year, and preterm birth is a risk factor in over 50% of all neonatal deaths. In addition, preterm birth can result in a range of long-term complications in survivors, with the frequency and severity of adverse outcomes rising with decreasing gestational age and decreasing quality of care. The economic costs of preterm birth are large in terms of immediate neonatal intensive care, ongoing long-term complex health needs, as well as lost economic productivity. Preterm birth is a syndrome with a variety of causes and underlying factors usually divided into spontaneous and provider-initiated preterm births. Consistent recording of all pregnancy outcomes, including stillbirths, and standard application of preterm definitions is important in all settings to advance both the understanding and the monitoring of trends. Context specific innovative solutions to prevent preterm birth and hence reduce preterm birth rates all around the world are urgently needed. Strengthened data systems are required to adequately track trends in preterm birth rates and program effectiveness. These efforts must be coupled with action now to implement improved antenatal, obstetric and newborn care to increase survival and reduce disability amongst those born too soon.
    Full-text · Article · Nov 2013 · Reproductive Health
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    • "In all, only 1.85% of births were excluded of the initial set. This proportion is lower than other studies in population data base [32,33]. But the excluded births did not have a random distribution, then the exclusion of these groups could have underestimated the association between maternal characteristic and PTB especially during the first period, nonetheless the effect on the rates seems to be insignificant since these exclusions did not affect the trends of PTB. "
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    ABSTRACT: Background: Preterm birth is a global problem in Perinatal and infant Health. Currently is gaining a growing attention. Rates of preterm birth have increased in most countries, producing a dramatic impact on public health. Factors of diverse nature have been associated to these trends. In Chile, preterm birth has increased since 90. Simultaneously, the advanced demographic transition has modified the characteristics of woman population related to maternity. The principal objective of this study is to analyze some sociodemographic characteristics of the maternal population over time, and their possible association to rates of preterm birth. The second aim is to identify groups of mothers at high risk of having a preterm child. Methods: This population-based study examined all liveborn singletons in Chile from 1991 to 2008; divided in three periods. Preterm birth rates were measured as % births <37 weeks of gestation. Logistic regression assessed the risk of preterm birth associated with mother's age, parity, and marital status, expressed as crude and adjusted odds ratios. Results: Over time, rates of preterm birth increased in overall population, especially during the third period (2001-2008). In the same time, characteristics of maternal population changed: significant increase of extreme reproductive ages, significant decrease in parity and increase in mothers living without a partner. Risk of preterm birth remained higher in groups of mothers: <18 and >38 years of age; without a partner; primiparas and grandmultiparas. However, global increase in preterm birth was not explained by the modification of socio demographics characteristics of maternal population. Conclusions: Some socio demographic characteristics remained associated with preterm birth over time. These associations allowed identifying five groups of mothers at higher risk to have a preterm child in the population. Increase in overall preterm birth affected all women, even those considered at "low sociodemographic risk" and the contribution of more recent period (2001-2008) to this increase is greater. Then, studied factors couldn't explain the increase in preterm birth. Further research will have to consider other factors affecting maternal population that could explain the observed trend of preterm birth.
    Full-text · Article · May 2013 · Reproductive Health
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    • "According to a trend study conducted from the perinatal information system for the countries of Latin America and the Caribbean (SIP), 40% of preterm births were associated with medical interventions [42]. Deliveries involving induction of labour or elective caesareans have increased over the past 20 years from 10% in 1985 to 18.5% in 2005, accompanied by an increase in preterm and very preterm births. "
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    ABSTRACT: Gestational age and birth weight are the principal determinants of newborn’s health status. Chile, a middle income country traditionally has public policies that promote maternal and child health. The availability of an exhaustive database of live births has allows us to monitor over time indicators of newborns health. This descriptive epidemiological study included all live births in Chile, both singleton and multiple, from 1991 through 2008. Trends in gestational age affected the rate of prevalence (%) of preterm births (<37 weeks, including the categories < 32 and 32–36 weeks), term births (37–41) and postterm births (42 weeks or more). Trends in birth weight affected the prevalence of births < 1500 g, 1500–2499 g, 2500–3999 g, and 4000 g or more. Data from an exhaustive register of live births showed that the number of term and postterm births decreased and the number of multiple births increased significantly. Birth weights exceeding 4000 g did not vary. Total preterm births rose from 5.0% to 6.6%, with increases of 28% for the singletons and 31% for multiple births (p for trend < 0.0001). Some categories increased even more: specifically preterm birth < 32 weeks increased 32.3% for singletons and 50.6% for multiple births (p for trend 0.0001). The overall rate of low birth weight infants (<2500 g) increased from 4.6% to 5.3%. This variation was not statistically significant for singletons (p for trend = 0.06), but specific analyses exhibited an important increase in the category weighing <1500 g (42%) similar to that observed in multiple births (43%). The gestational age and birth weight of live born child have significantly changed over the past two decades in Chile. Monitoring only overall rates of preterm births and low-birth-weight could provide restricted information of this important problem to public health. Monitoring them by specific categories provides a solid basis for planning interventions to reduce adverse perinatal outcomes. This epidemiological information also showed the need to assess several factors that could contribute to explain these trends, as the demographics changes, medical interventions and the increasing probability of survival of extremely and very preterm child.
    Full-text · Article · Nov 2012 · BMC Pregnancy and Childbirth
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