8. Sobreposición de RNBP, Preterminos & defectos al nacimiento Nacimientos de Bajo peso 7.9% Nacimientos preterminos 12.3% Defectos al nac. ~3-4% Entre los RN de BP: 2/3 son pretermino entre pretermino: más de 43% son BPN (algunos pretermino no son a BP al nac.) . .
66. Tipos de defectos al nacimiento y riesgo de prematurez Tipos de defectos al nacimiento RR ( 95 %) Anencefalia 3.51 (0.97-11) Espina bifida 3.04 (1.78- 5.03) Transposicion de g. vasos 1.62 (0.95-2.63) Labio paladar 2.41 (1.52-3.73) Atresia intestinal 10.37 (5.42-20.1) Displasia de cadera 1.10 ( 0.72-1.64) Gastrosquisis 8.75 (5.24-14.6) Sindrome de Down 3.93 (2.29-3.99)
In developed nations, most low-birthweight infants are preterm. In under-developed nations, the proportion of term low-birthweight infants is higher due to the greater prevalence of malnutrition. In the U.S., two-thirds of low-birthweight infants are preterm (<37 weeks), and half of preterm infants weigh less than 2,500 grams. This is explained on the next slide.
Perinatal morbidity declines rapidly between 26 and 30 weeks. Intraventricular hemorrhage, one of the most feared complications of premature birth, occurs rarely in infants born after 32 weeks of gestation following maturation of the germinal matrix in the ventricles in the brain. This slide is also from the population-based cohort of 8,523 infants born in 1997-98 in Memphis mentioned in slide 23. Source: Mercer BM. Preterm premature rupture of the membranes. Obstet Gynecol 2003;101:178-93.
Spontaneous preterm births follow preterm labor, preterm premature rupture of membranes (PPROM), multiple gestations, cervical insufficiency, or other related diagnoses. They account for about three-quarters of preterm births in the U.S. annually. Indicated preterm deliveries follow medical or obstetric disorders that place the mother and/or fetus at risk such as maternal hypertension, diabetes, placenta previa or abruption, and intrauterine growth restriction. These preterm births account for about one-quarter of births occurring before 37 weeks. Sources: Goldenberg RL, Iams JD, Mercer BM, et al. The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network. Am J Public Health 1998;88:233-8; Meis PJ, Michielutte R, Peters TJ, et al. Factors associated with preterm birth in Cardiff, Wales. II. Indicated and spontaneous preterm birth. Am J Obstet Gynecol 1995;173:597-602; Meis PJ, Goldenberg RL, Mercer BM, et al. The preterm prediction study: risk factors for indicated preterm births. Maternal-Fetal Medicine Units Network of the National Institute of Child Health and Human Development. Am J Obstet Gynecol 1998;178:562-7.
About half of women who present with either preterm labor or preterm premature rupture of membranes (PPROM) have one or more risk factors, but half do not. Risk factors associated with spontaneous preterm birth include genital tract infection, non-white race, multiple gestation, 2nd trimester bleeding, low pre-pregnancy weight, and a history of previous preterm birth. Maternal smoking and bleeding in the second trimester are particularly associated with PPROM. Sources: Iams JD, Creasy RK. Preterm labor and delivery, Chapter 34. In: Creasy RK, Resnik R, Iams JD, eds. Maternal-Fetal Medicine: Principles and Practice, 5th ed., 2004.
Common maternal conditions associated with indicated preterm births are shown in this slide representing data from an observational study by Meis et al. Source: Meis PJ, Goldenberg RL, Mercer BM, et al. The preterm prediction study: risk factors for indicated preterm births. Maternal-Fetal Medicine Units Network of the National Institute of Child Health and Human Development. Am J Obstet Gynecol 1998;178:562-7.
Infants born preterm can suffer from the acute, short-term and long-term consequences of being born too early. The conditions presented on this slide are discussed in greater detail in the section titled “Neonatal and Postneonatal Sequelae of the Preterm Infant.” RDS = respiratory distress syndrome IVH = intraventricular hemorrhage, two patterns of brain injury that are often precursors of cerebral palsy PVL = periventricular leukomalacia PDA = patent ductus arteriosus, a persistently open ductus arteriosus which allows persistence of the fetal pattern of circulation through the heart and lungs and may require surgical correction NEC = necrotizing enterocolitis, a condition in which there is inflammation and potential injury of the small bowel, sometimes requiring removal if sections become necrotic (often NEC can be managed medically) and leaving the infant with inadequate nutritional absorption Chronic lung disease may occur in infants who require mechanical ventilation as treatment for RDS. The impact of prematurity can be lifelong. Source: Iams JD, Creasy RK. Preterm labor and delivery, Chapter 34. In: Creasy RK, Resnik R, Iams JD, eds. Maternal-Fetal Medicine: Principles and Practice, 5th ed., 2004.
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