The Influence of Obstetric Practices on Late Prematurity

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In this article, the authors review the standard management of several maternal and fetal complications of pregnancy and examine the effect these practices may have on the late preterm birth rate. Given the increasing rate of late preterm birth and the increased recognition of the morbidity and mortality associated with delivery between 34 and 37 weeks, standard obstetric practices and practice patterns leading to late preterm birth should be critically evaluated. The possibility of expectant management of some pregnancy complications in the late preterm period should be investigated. Furthermore, prospective research is warranted to investigate the role of antenatal corticosteroids beyond 34 weeks.

Section snippets

Management of pregnancy complications: general principles

When complications arise in pregnancy, physicians must assess the risks for continuing the pregnancy with the risks associated with immediate delivery. Preterm birth—whether spontaneous or indicated—carries with it the risk for significant neonatal morbidity and mortality. Accordingly, certain complications are expectantly managed with the goal of allowing the pregnancy to continue to a more advanced gestational age at which delivery carries less risk for prematurity-related morbidity to the

Spontaneous preterm labor

Preterm labor (PTL)—defined as regular uterine contractions leading to progressive cervical dilation before 37 weeks of gestation—is the most common cause of antepartum admission [14] and precedes up to 50% of preterm births [15]. Among late preterm births, spontaneous PTL accounts for a similar proportion of deliveries. In a recent study by McIntire and Leveno [16], approximately 45% of late preterm births at a single institution were attributed to idiopathic PTL. National data suggest that

Hypertensive disorders: gestational hypertension and preeclampsia

Hypertensive disorders are the most common medical complication of pregnancy and are estimated to affect 6% to 10% of all pregnancies [30]. Gestational hypertension (gHTN) is diagnosed as new finding of a systolic blood pressure (BP) of at least 140 mm Hg or a diastolic BP of at least 90 mm Hg on at least two occasions at least 6 hours apart after the 20th week of gestation in women known to be previously normotensive. Preeclampsia (PEC) is defined as the finding of hypertension with new-onset

Intrauterine growth restriction

IUGR is classically defined as a fetus with an estimated fetal weight decreasing lower than the 10th percentile for the given gestational age [52]. Although many fetuses with estimated weights at less than the 10th percentile are simple constitutionally small fetuses at the lower end of the normal growth spectrum, some fetuses measure lower than the 10th percentile because of suboptimal intrauterine growth. Maternal factors associated with IUGR include coexisting medical disorders

Summary

Although evidence of worsening maternal or fetal status clearly justifies iatrogenic late preterm delivery, many current obstetric practice guidelines routinely suggest delivery between 34 and 37 weeks. Given the increasing rate of late preterm birth and the increased recognition of the morbidity and mortality associated with delivery between 34 and 37 weeks, these standard obstetric practices and practice patterns leading to late preterm birth should be critically evaluated. The possibility of

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      In practice, newborns with GA of 34 to 36 weeks and six days tend to be considered, both by obstetricians and neonatologists, as having a very similar risk to those born at term. This attitude is reflected in the obstetrician's routine, for instance, regarding the greater tolerance toward interrupting the pregnancy when there are maternal and/or fetal complications from 34 weeks on,1 as well as in the neonatologist's routine, regarding the tendency to keep these newborns in low-risk nurseries or rooming-in care2 and provide early discharge.3 These practices are due, at least in part, to results of studies by Goldenberg et al.4 and by De Palma et al.5 These authors evaluated the gain for each additional week of gestation between 22 and 37 weeks in increased survival and decreased risk of complications and/or sequelae.

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