He enviado antes un comentario similar a este que mando ahora sobre la inducción del parto en gestaciones de más de 41 semanas. No sé qué ha pasado ni por qué no se ha publicado aún ya que he mandado un comentario posterior y sí que ha aparecido en el blog. En fin, lo que quiero comentar es que, Uptodate es una herramienta on-line donde se puede encontrar la última evidencia en muchos y diversos temas de salud. Se basa en una amplia bibliografía y es base de muchos de los protocolos que se manejan en los hospitales de todo el mundo y las recomendaciones del ministerio. Buscando el manejo del parto postérmino, las conclusiones son diferentes a las que aquí comentáis así que me tomo la libertad de pegar todo el artículo y señalar dos de los epígrafes de las conclusiones (me gustaría poner sólo el enlace, pero es una web de acceso con suscripción). Como la mayoría de los artículos científicos, está escrito en inglés así que he traducido esos epígrafes. The risks of fetal and neonatal death increase with increasing gestational age after 40 weeks of gestation, but the absolute risk of death is low. Intrauterine infection, placental insufficiency or cord compression leading to fetal hypoxia and asphyxia, and meconium aspiration are thought to contribute to the excess perinatal deaths. (See 'Morbidity and mortality' above and 'Expectant management' above.) [Los riesgos de muerte fetal y neonatal aumentan conforme aumenta la edad gestacional después de las 40 semanas de gestación pero el riesgo absoluto de muerte es bajo. Se piensa que la infección intrauterina, la insuficiencia placentaria y la compresión del cordón que lleva a una hipoxia o asfixia fetal ( aclaración: llega un punto en el embarazo en el que la producción de líquido amniótico es cada vez menor por lo que el feto puede moverse cada vez menos y el cordón no tiene la protección ante la presión ejercida por los movimientos fetales que le proporciona un medio líquido) contribuyen a un exceso de muertes perinatales.] For women ≥410/7ths weeks of gestation, we suggest induction rather than expectant management (Grade 2A). Induction is associated with lower perinatal mortality than expectant management and does not increase the risk of cesarean delivery. The benefits of routine induction are modest, however, and depending on their values and preferences, some women may choose to be managed expectantly. Para las mujeres en la semana 41 o más se recomienda la inducción antes que el manejo espectante (evidencia grado 2A). La inducción está asociada con una mortalidad perinatal inferior que el manejo espectante y no aumenta el riesgo de cesárea. Los beneficios de la inducción de rutina son modestos y dependiendo de los valores y las preferencias, algunas mujeres pueden elegir el manejo espectante. Postterm pregnancy Author Errol R Norwitz, MD, PhD Section Editor Charles J Lockwood, MD Deputy Editor Vanessa A Barss, MD Disclosures All topics are updated as new evidence becomes available and our peer review process is complete. Literature review current through: Nov 2012. | This topic last updated: jun 15, 2012. INTRODUCTION — The timely onset of labor and delivery is an important determinant of perinatal outcome. Both preterm and postterm births are associated with higher rates of perinatal morbidity and mortality than pregnancies delivering at term. DEFINITION — Postterm pregnancy refers to a pregnancy that has ≥420/7ths weeks of gestation or ≥294 days from the first day of the last menstrual period [1]. Accurate pregnancy dating is critical to the diagnosis. PREVALENCE — In the United States, approximately 28 percent of pregnancies deliver in the 40th and 41st week and 6 percent deliver at ≥42 weeks [2]. A study of postterm birth rates in 13 European countries observed a wide range across the continent: from 0.4 percent in Austria and Belgium to 8.1 percent in Denmark [3]. The authors attributed the variation to differences in prenatal assessment of gestational age and obstetric practices. The prevalence of postterm pregnancy in a population is affected by several factors. One of the most important factors is whether routine early ultrasound assessment of gestational age is performed. Among pregnancies dated by first trimester ultrasound examination, the prevalence of delivery ≥42 weeks is about 2 percent (versus 6 to 12 percent by last menstrual period [LMP]) [4-7] and the prevalence of delivery ≥41 weeks ranges from 5 to 11 percent (versus 13 to 22 percent by LMP) [6,8-10]. In a meta-analysis that compared the rate of labor induction for postterm pregnancy in women who underwent sonographic estimation of their delivery date (EDD) in early pregnancy with the rate in women whose EDD was calculated from their LMP, early routine ultrasound examination reduced the rate of intervention for postterm pregnancy (OR 0.68, 95% CI 0.57-0.82) [4]. Other factors that affect the prevalence of postterm pregnancy in a population include the rate of spontaneous preterm birth, the prevalence of primigravid women (who are more likely to deliver postterm), and the prevalence of women with pregnancy complications (who are less likely to deliver postterm). Local practice patterns, such as the rate of scheduled cesarean delivery and elective labor induction, will also affect the prevalence of postterm birth. ETIOLOGY AND RISK FACTORS — The majority of postterm pregnancies have no known etiology. In rare cases, postterm pregnancy can be attributed to known defects in fetal production of hormones involved in parturition. In the past, anencephaly was a cause of postterm pregnancy in the absence of polyhydramnios, but these pregnancies are now routinely detected antepartum and terminated or induced. X-linked ichthyosis (MIM 308100), which is associated with placental sulfatase deficiency, is another rare cause of postterm pregnancy [11]. Women at highest risk of postterm pregnancy are those with a previous postterm pregnancy. After one postterm pregnancy, the risk of a second postterm birth is increased two- to three-fold; the risk of recurrence is quadrupled after two prior postterm pregnancies [12-14]. Additional, more modest risk factors (RR <2) include [12,13,15-20]: Nulliparity Male fetus Maternal obesity Maternal or paternal personal history of postterm birth Maternal race/ethnicity (African-American women, Latina, and Asian women are at lower risk than Caucasians) MORBIDITY AND MORTALITY — Postterm pregnancy is associated with fetal, neonatal, and maternal risks [21-25]. Fetal and neonatal risks — Postterm fetuses tend to be larger than term fetuses, with a higher incidence of macrosomia (≥4500 g) (2.5 to 10 percent versus 0.8 to 1 percent at term) [26-28]. Complications of macrosomia include prolonged labor, cephalopelvic disproportion, and shoulder dystocia, all of which increase the risk of birth injury. (See "Fetal macrosomia" and "Timing and route of delivery in pregnancies at risk of shoulder dystocia".) In contrast, up to 20 percent of postterm fetuses have "fetal dysmaturity (postmaturity) syndrome," a term used to describe infants with characteristics of chronic intrauterine malnutrition [29-31]. These fetuses are at increased risk of umbilical cord compression due to oligohydramnios, and nonreassuring antepartum or intrapartum fetal heart rate patterns due to placental insufficiency or cord compression. Meconium passage is common and may be related to physiological maturation of the gut or fetal hypoxia. Neonates have a long thin body, long nails, and are small for gestational age. Their skin is dry (vernix caseosa is decreased or absent), meconium stained, parchment-like, and peeling; it appears loose, especially over the thighs and buttocks, and has prominent creases; lanugo hair is sparse or absent, while scalp hair is increased. These fetuses/neonates are at risk for the short- and long-term morbidity typically seen in intrauterine growth restriction/small for gestational age infants. (See "Postterm infant" and "Fetal growth restriction: Evaluation and management", section on 'Outcome' and "Small for gestational age infant".) Perinatal mortality increases as pregnancy extends beyond 39 to 40 weeks of gestation due to increases in both non-anomalous stillbirths and early neonatal deaths [32-35]. Intrauterine infection, placental insufficiency and cord compression leading to fetal hypoxia, asphyxia, and meconium aspiration are thought to contribute to the excess perinatal deaths [36,37]. The perinatal mortality rate at ≥42 weeks of gestation is twice the rate at term, increasing four-fold at 43 weeks, and five- to seven-fold at 44 weeks [24,37-40]. Neonates born at ≥41 weeks of gestation experience one-third greater neonatal mortality than term neonates born at 38 to 40 weeks of gestation [32]. However, the absolute risk of fetal or neonatal death is low. (See 'Expectant management' below and "Postterm infant", section on 'Perinatal mortality'.) The long-term effects of postterm birth are unclear. Studies on long-term outcomes for children born postterm are reviewed separately. (See "Postterm infant", section on 'Long-term outcome'.) Maternal risks — Maternal risks of postterm pregnancy include an increased frequency of labor abnormalities and sequelae of labor induction and fetal macrosomia. These sequelae include failed induction, third and fourth degree perineal lacerations, and postpartum hemorrhage [41-43]. MANAGEMENT — The following discussion refers to the singleton, cephalic fetus of an otherwise uncomplicated pregnancy that reaches 41 weeks of gestation. Multiple gestations, non-cephalic presentations, and complicated pregnancies are generally delivered before 41 weeks. We favor induction of well-dated postterm pregnancies at or shortly after 410/7ths weeks of gestation, irrespective of cervical status. The alternative is expectant management with ongoing fetal assessment with intervention if fetal assessment is not reassuring or spontaneous labor does not occur by a predefined gestational age. Both of these approaches are associated with low complication rates in the low-risk postterm gravida [44]. Induction — Induction of postterm pregnancy rather than expectant management with fetal monitoring is supported by several lines of evidence: Lower perinatal mortality and morbidity In a 2012 meta-analysis of randomized trials comparing a policy of labor induction to a policy of awaiting spontaneous onset of labor at 39 to 42 weeks: Routine labor induction at >41 weeks of gestation compared with expectant management resulted in lower perinatal mortality (1/2814 versus 9/2785; RR 0.30, 95% CI 0.09-0.99; 10 trials) and a lower rate of meconium aspiration syndrome (RR 0.61, 0.40-0.92; 5 trials, 1395 patients) [45]. For induction at 410/7ths, the risk of perinatal mortality was also lower than with expectant management, but did not achieve statistical significance (0/501 versus 2/497; RR 0.33, 95% CI 0.03-3.17; 4 trials, 998 patients). When fetal mortality is based on the number of fetal deaths per 1000 ongoing pregnancies (rather than per 1000 deliveries), an analysis of fetal versus neonatal mortality rates concluded the rate of fetal demise was significantly higher than the rate of neonatal death at any gestational age ≥403/7ths weeks of gestation [46]. No increase in or a reduction in cesarean delivery Meta-analyses have reported that routine induction at >41 weeks results in no increase in the risk of cesarean delivery compared with expectant management (RR 0.91, 95% CI 0.82-1.00; 12 trials, 5994 patients) [45] or a decrease in the cesarean birth rate (pooled cesarean delivery rate with induction at ≥41 weeks: 17.5 versus 20.1 percent; P = 0.04; 8 trials, 6054 women) [47]. Patient satisfaction A survey of women at 41 weeks of gestation reported that 74 percent preferred induction to expectant management [48]. We agree with guidelines that suggest routine induction between 410/7ths and 420/7ths weeks of gestation rather than expectant management and monitoring as intervention at this time reduces perinatal mortality without increasing perinatal morbidity or cesarean delivery rates [8,49]. The exact timing during this week should take into account clinician and patient preferences and local circumstances. We favor induction of well-dated postterm pregnancies at or shortly after 410/7ths weeks of gestation. However, this approach has not been universally accepted [50], in part because of the low absolute rates of fetal and neonatal death: at 410/7ths weeks, 527 inductions would be necessary to prevent one perinatal death; at 43 weeks, 195 inductions would be necessary to prevent one perinatal death [51]. We utilize cervical ripening agents in women with unfavorable cervices. In women wishing to avoid pharmacologic agents for cervical ripening and induction, membrane sweeping (also called stripping) can be performed if the cervix is sufficiently dilated, and reduces the proportion of patients who remain undelivered at 42 weeks. This was illustrated in a trial that randomly assigned 742 low-risk women at 41 weeks of gestation to membrane sweeping every 48 hours or expectant management [52]. At baseline, the Bishop score was <6 in 78 percent of women in the intervention group; the expectant management group did not undergo cervical examination. Serial membrane sweeping resulted in fewer pregnancies reaching ≥420/7ths weeks (23 versus 41 percent without membrane sweeping, RR 0.57 95% CI 0.46-0.71, number needed to treat 6). The optimum time to initiate membrane sweeping and the frequency (once versus on multiple days) has not been studied. Beginning anytime after 39 weeks of gestation is reasonable. (See "Techniques for ripening the unfavorable cervix prior to induction".) Expectant management — Postterm pregnancy is a universally accepted indication for antenatal fetal monitoring because the risk of antepartum fetal demise increases with advancing gestational age. In large studies from the United Kingdom, the risk of antepartum fetal demise was [53]: 40 to 41 weeks: 0.86 to 1.08 per 1000 ongoing pregnancies 41 to 42 weeks: 1.2 to 1.27 per 1000 ongoing pregnancies 42 to 43 weeks: 1.3 to 1.9 per 1000 ongoing pregnancies >43 weeks: 1.58 to 6.3 per 1000 ongoing pregnancies However, the efficacy of antenatal fetal assessment for preventing unexplained fetal demise in postterm fetuses has not been validated by appropriately sized and placebo-controlled randomized trials, and probably never will be evaluated in this way because of ethical and medicolegal concerns of assigning some pregnancies to an unmonitored group. One small trial that compared two methods of fetal assessment has been performed, and did not find a difference in neonatal outcome between groups [54]. The optimal type and frequency of fetal testing, and the gestational age for beginning monitoring, have not been determined. We suggest monitoring fetal well-being by the nonstress testing with amniotic fluid volume assessment or by the biophysical profile (BPP); neither method has been proven to be superior. Doppler ultrasonography of the umbilical artery has no proven benefit in monitoring the postterm fetus and is not recommended for this indication [55,56]. Case control studies support initiating antepartum fetal surveillance between 410/7ths and 420/7ths weeks of gestation (287 to 294 days) [57,58]. We suggest twice weekly testing beginning at 410/7ths weeks or shortly thereafter. (See "Overview of fetal assessment", section on 'Antenatal testing methods'.) Induction is indicated for development of any of the usual obstetrical indications, including evidence of oligohydramnios [59,60]. Adverse pregnancy outcomes (nonreassuring fetal heart rate tracing, neonatal intensive care unit admission, low Apgar) are more likely when oligohydramnios is present [59-64]. Frequent assessment is important because amniotic fluid can become severely reduced within 24 to 48 hours [65]. (See "Oligohydramnios".) INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon. Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.) Basics topics (see "Patient information: When your baby is overdue (The Basics)") Beyond the Basics topics (see "Patient information: Postterm pregnancy (Beyond the Basics)") SUMMARY AND RECOMMENDATIONS Postterm pregnancy refers to a pregnancy that is ≥420/7ths weeks of gestation or 294 days from the first day of the last menstrual period (LMP). (See 'Definition' above.) In pregnancies dated by first trimester ultrasound examination, the prevalence of postterm pregnancy is about 2 percent and fewer inductions are performed for postterm pregnancy than in pregnancies dated by LMP. (See 'Prevalence' above.) After one postterm pregnancy, the risk of another such pregnancy in the subsequent birth is increased two- to three-fold; the risk of recurrence is quadrupled after two prior postterm pregnancies. (See 'Etiology and risk factors' above.) The risks of fetal and neonatal death increase with increasing gestational age after 40 weeks of gestation, but the absolute risk of death is low. Intrauterine infection, placental insufficiency or cord compression leading to fetal hypoxia and asphyxia, and meconium aspiration are thought to contribute to the excess perinatal deaths. (See 'Morbidity and mortality' above and 'Expectant management' above.) Maternal and neonatal morbidity in postterm pregnancy is related, in part, to complications from fetal macrosomia. Dysmaturity, which occurs in up to 20 percent of postterm fetuses, also results in short- and long-term morbidity. (See 'Morbidity and mortality' above.) For women ≥410/7ths weeks of gestation, we suggest induction rather than expectant management (Grade 2A). Induction is associated with lower perinatal mortality than expectant management and does not increase the risk of cesarean delivery. The benefits of routine induction are modest, however, and depending on their values and preferences, some women may choose to be managed expectantly. (See 'Management' above.) Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES World Health Organization. International Statistical Classification of Diseases and Related Health Problems. Geneva, 2006. National Vital Statistics Reports. Births: Final data for 2009 www.cdc.gov/nchs/data/nvsr/nvsr60/nvsr60_01.pdf (Accessed on May 31, 2012). Zeitlin J, Blondel B, Alexander S, et al. 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