Temporal trends of preterm birth subtypes and neonatal outcomes
ABSTRACT 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.
- SourceAvailable from: Luis F GONCALVES
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- "present results should be considered with the caveat that they may reflect human biological variation that is unique to this population. The relatively high rate of late preterm births in the present sample fits the demographic profile for Latin America as reported by the Pan American Health Organization based on data from 1.7 million births that occurred between 1985 and 2003 in more than 50 maternity hospitals (Barros and Velez, 2006). The mean birth weight among spontaneous preterm birth in this larger sample was 2541 grams (sd, 741) at an average gestational age of 33.9 weeks (sd, 2.9), very close to the present study outcome. "
ABSTRACT: The past two decades in the United States have seen a 24% rise in spontaneous late preterm delivery (34-36 weeks) of unknown etiology. This study tested the hypothesis that fetal growth was identical prior to spontaneous preterm (n = 221, median gestational age at birth 35.6 weeks) and term (n = 3706) birth among pregnancies followed longitudinally in Santiago, Chile. The hypothesis was not supported: Preterm-delivered fetuses were significantly larger than their term-delivered peers by mid-second trimester in estimated fetal weight, head, limb, and abdominal dimensions, and they followed different growth trajectories. Piecewise regression assessed time-specific differences in growth rates at 4-week intervals from 16 weeks. Estimated fetal weight and abdominal circumference growth rates slowed at 20 weeks among the preterm-delivered, only to match and/or exceed their term-delivered peers at 24-28 weeks. After an abrupt growth rate decline at 28 weeks, fetuses delivered preterm did so at greater population-specific sex and age-adjusted birth weight percentiles than their peers from uncomplicated pregnancies (P < 0.01). Growth rates predicted birth timing: one standard score of estimated fetal weight increased the odds ratio for late preterm birth from 2.8 prior to 23 weeks, to 3.6 (95% confidence interval, 1.82-7.11, P < 0.05) between 23 and 27 weeks. After 27 weeks, increasing size was protective (OR: 0.56, 95% confidence interval, 0.38-0.82, P = 0.003). These data document, for the first time, a distinctive fetal growth pattern across gestation preceding spontaneous late preterm birth, identify the importance of mid-gestation for alterations in fetal growth, and add perspective on human fetal biological variability.American Journal of Human Biology 03/2009; 21(2):141-50. DOI:10.1002/ajhb.20840 · 1.93 Impact Factor
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ABSTRACT: The Group Allocation Multiple Access (GAMA) protocol for scheduling real-time and datagram traffic in a singlechannel, single-hop, packet-radio network is specified and analyzed. By maintaining a dynamically-sized cycle that changes in length depending on the amount of network traffic, GAMA is able to provide bandwidth guarantees to the members of its "transmission group"; member stations are able to transmit real-time data at a specified rate. Each cycle contains a contention period and a group-transmission period; a station with data to send competes for the right to be added to the transmission group by successfully completing an RTS/CTS message exchange during the contention period. Once a station is a member of the transmission group, it is able to transmit a collision-free data packet during each cycle. As long as a station has data to send, it maintains its position in the group. This can be viewed as either allowing stations to "share the floor" in an organized manner, or as es...Proceedings of SPIE - The International Society for Optical Engineering 01/1997; DOI:10.1117/12.264308 · 0.20 Impact Factor
Article: Genetic influences on preterm birth[Show abstract] [Hide abstract]
ABSTRACT: The high prevalence, increasing frequency, and adverse outcomes for mothers and infants of preterm birth have led to heightened awareness of this public health concern. The causes of preterm birth are likely to be multifactorial, with genetic, infectious, nutritional, behavioral, and other environmental contributors. Because of important differences in the physiology of human pregnancy and that of nonprimate mammals, extrapolation of mechanisms from animal model systems to humans has had limited impact on the understanding of human prematurity. This review summarizes work from many groups that implicates important genetic contributions to human preterm birth. These efforts use epidemiological, classical genetic, and more recently, genomic science approaches to determine pregnancies at risk for preterm delivery and to facilitate an understanding of the substantial racial disparity in preterm birth. Data revealing racial and familial predispositions to prematurity, along with genetic polymorphisms conferring increased preterm birth, promise new insights into the understanding and treatment of this critical problem.Seminars in Reproductive Medicine 02/2007; 25(1):40-51. DOI:10.1055/s-2006-956774 · 3.00 Impact Factor