Timing of Indicated Late-Preterm and Early-Term Birth

Columbia University, New York, New York, United States
Obstetrics and Gynecology (Impact Factor: 5.18). 08/2011; 118(2 Pt 1):323-33. DOI: 10.1097/AOG.0b013e3182255999
Source: PubMed


The growing public health awareness of prematurity and its complications has prompted careful evaluation of the timing of deliveries by clinicians and hospitals. Preterm birth is associated with significant morbidity and mortality, and affects more than half a million births in the United States each year. In some situations, however, a late-preterm or early-term birth is the optimal outcome for the mother, child, or both owing to conditions that can result in worse outcomes if pregnancy is allowed to continue. These conditions may be categorized as placental, maternal, or fetal, including conditions such as placenta previa, preeclampsia, and multiple gestations. Some risks associated with early delivery are common to all conditions, including prematurity-related morbidities (eg, respiratory distress syndrome and intraventricular hemorrhage) as well as maternal intrapartum morbidities such as failed induction and cesarean delivery. However, when continuation of the pregnancy is associated with more risks such as hemorrhage, uterine rupture, and stillbirth, preterm delivery maybe indicated. In February 2011, the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the Society for Maternal-Fetal Medicine held a workshop titled "Timing of Indicated Late Preterm and Early Term Births." The goal of the workshop was to synthesize the available information regarding conditions that may result in medically indicated late-preterm and early-term births to determine the potential risks and benefits of delivery compared with continued pregnancy, determine the optimal gestational age for delivery of affected pregnancies when possible, and inform future research regarding these issues. Based on available data and expert opinion, optimal timing for delivery for specific conditions was determined by consensus.

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    • "Infants were excluded if their underlying diagnosis was consistent with a defect associated with abnormal nitric oxide levels or ciliary dysfunction. Late-preterm infants (defined as 34e37 weeks post-conceptual age) were enrolled, but infants born prior to 34 weeks post-conceptual age were excluded [20] "
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    ABSTRACT: Primary ciliary dyskinesia (PCD), a disease of impaired respiratory cilia motility, is often difficult to diagnose. Recent studies show low nasal nitric oxide (nNO) is closely linked to PCD, allowing the use of nNO measurement for PCD assessments. Nasal NO cutoff values for PCD are stratified by age, given nNO levels normally increase with age. However, normative values for nNO have not been established for infants less than 1 year old. In this study, we aim to establish normative values for nNO in infants and determine their utility in guiding infant PCD assessment. We obtained 42 nNO values from infants less than 1 year old without a history of PCD or recurrent sinopulmonary disease. Using regression analysis, we estimated the mean age-adjusted nNO values and established a 95% prediction interval (PI) for normal nNO. Using these findings, we were able to show 14 of 15 infant PCD patients had abnormally low nNO with values below the 95% PI. In this study we determined a regression model that best fits normative nNO values for infants less than 1 year old. This model identified the majority of PCD infants as having abnormally low nNO. These findings suggest nNO measurement can help guide PCD assessment in infants, and perhaps other pulmonary diseases with a link to low nNO. With early assessments, earlier clinical intervention may be possible to slow disease progression and help reduce pulmonary morbidity. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Respiratory medicine 07/2015; 109(9). DOI:10.1016/j.rmed.2015.07.010 · 3.09 Impact Factor
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    • "Furthermore, PTB can occur “early” (<34 weeks’ gestation) or “late” (34–36 weeks’ gestation). Pregnancy complications leading to medical inductions disproportionately contribute to late PTB, as compared to early PTB [6-8]. A recent systematic review of 84 studies demonstrated that prepregnancy obesity is associated with a 1.24-fold increased risk of PTB [9]. "
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    ABSTRACT: To evaluate the association between prepregnancy body mass index (BMI) is associated with early vs. late and medically-induced vs. spontaneous preterm birth (PTB) subtypes. Using data from the Boston Birth Cohort, we examined associations of prepregnancy BMI with 189 early (<34 completed weeks) and 277 late (34-36 completed weeks) medically-induced PTBs and 320 early and 610 late spontaneous PTBs vs. 3281 term births (37-44 weeks) in multinomial regression. To assess for mediation by important pregnancy complications, we performed sequential models with and without hypertensive disorders of pregnancy, chorioamnionitis, and gestational diabetes. Prevalence of prepregnancy obesity (BMI >= 30.0 kg/m2) was 28% among mothers with medically-induced PTBs, 18% among mothers with spontaneous PTBs, and 18% among mothers with term births (p = <0.001). After adjustment for demographic and known risk factors for PTB, prepregnancy obesity was associated with higher odds of both early [OR 1.78 (1.19, 2.66)] and late [OR 1.49 (1.09, 2.04)] medically-induced PTB. These effect estimates were attenuated with inclusion of hypertensive disorders of pregnancy and gestational diabetes. For spontaneous deliveries, prepregnancy obesity was associated with decreased odds of PTB (0.76 [0.58, 0.98]) and underweight was nearly associated with increased odds of PTB (1.46 [0.99, 2.16]). Prepregnancy obesity is associated with higher risk of medically-induced, but not spontaneous PTB. Hypertensive disorders of pregnancy and gestational diabetes appear to partially explain the association between prepregnancy obesity and early and late medically-induced PTB.
    BMC Pregnancy and Childbirth 04/2014; 14(1):153. DOI:10.1186/1471-2393-14-153 · 2.19 Impact Factor
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    • "In terms of external validity, the study participation criteria were defined in order to include only low risk women, and therefore we had no reason to believe that the mother or foetus would be put at risk when caesarean section was scheduled after 39 gestational weeks. Thus, the results may apply to women with a non-medical reason for a planned caesarean section and to women with an indicated caesarean section where timing prior to 39 weeks and five days would not be indicated [24]. Since nearly 95% of the women in this trial were white Europeans, scheduling caesarean section after 39 weeks may carry a larger risk of having an unscheduled procedure in populations with different ethnicities [25]. "
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    ABSTRACT: To compare the impact of scheduling caesarean section prior to versus after 39 completed weeks of gestation on the occurrence of unscheduled caesarean section and rescheduling of the procedure. Secondary analysis from a multicentre randomised open-label trial including singleton pregnant women with a healthy foetus and a reliable due date. Women were allocated by computerized telephone randomisation to planned caesarean section at 38 weeks and three days or 39 weeks and three days. The outcomes were unscheduled deliveries with provided reasons, such as spontaneous labour onset or supervening complications, and any changes in the scheduled delivery date. Statistical analyses were according to intention-to-treat using Fisher's exact test. From March 2009 to June 2011 1,274 women were included. Median difference in gestational age at delivery was six days. Compared to the 38 weeks group, the women in the 39 weeks group were more likely to have an unscheduled caesarean section (15.2% vs. 9.3%; RR 1.64, 95% CI 1.21; 2.22), to deliver between 6 pm and 8 am (10 % vs. 6%; RR 1.68, 95% CI 1.14; 2.47), or to have the procedure rescheduled (36.7% vs. 23%; RR 1.6, 95% CI 1.34;1.90). Scheduling caesarean section after 39 weeks leads to a 60% increase in unscheduled caesarean sections and a 70% increase in delivery outside regular work hours as compared to scheduling of the procedure prior to 39 weeks. NCT00835003
    PLoS ONE 12/2013; 8(12):e84744. DOI:10.1371/journal.pone.0084744 · 3.23 Impact Factor
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