The second stage of labor.

The second stage of labor extends from complete cervical dilatation to delivery. During this stage, descent and rotation of the presenting part occur as the fetus passively negotiates its passage through the birth canal. Generally, descent begins during the deceleration phase of dilatation as the cervix is drawn upward around the fetal presenting part.

Dysfunctional labor and delivery: adverse effects on offspring.

There is no doubt that parturition can produce fetal and neonatal adversity, but the frequency with which this occurs is uncertain, particularly in modern healthcare settings. Moreover, there is a paucity of recent studies in this area. Substantial challenges impede epidemiologic study of the effect of parturition on offspring.

The active phase of labor.

The active phase of labor begins at various degrees of dilatation when the rate of dilatation transitions from the relatively flat slope of the latent phase to a more rapid slope. No diagnostic manifestations demarcate its onset, other than accelerating dilatation. It ends with apparent slowing of dilatation, a deceleration phase, which is usually short in duration and frequently undetected.

The latent phase of labor.

The latent phase of labor extends from the initiation of labor to the onset of the active phase. Because neither margin is always precisely identifiable, the duration of the latent phase often can only be estimated. During this phase, the cervix undergoes a process of rapid remodeling, which may have begun gradually weeks before.

Clinical evaluation of labor: an evidence- and experience-based approach.

During labor mother and fetus are evaluated at intervals to assess their well-being and determine how the labor is progressing. These assessments require skillful physical diagnosis and the ability to translate the acquired information into meaningful prognostic decision-making. We describe a coordinated approach to the assessment of labor.

Guidelines for labor assessment: failure to progress?

The ongoing debate about what models of cervical dilatation and fetal descent should guide clinical decision-making has sown uncertainty among obstetric practitioners. We previously argued that the adoption of recently published labor assessment guidelines promoted by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine may have been premature. Before accepting any new clinical approaches as the standard of care, their underlying hypotheses should be thoroughly tested to ensure they are at least equivalent (or, preferably, superior) to existing management paradigms.

Obstetric practice guidelines: labor's love lost?

Implementation of clinical practice guidelines may moderate health care costs, improve care, reduce medicolegal liability, and provide a uniformity in care allowing meaningful investigation of treatments and outcomes. However, new guidelines are often uncritically embraced by clinicians, risk management organizations, insurance companies, and the courts as the standard of care. Adoption of incompletely vetted recommendations can lead to patient harm.

The assessment of labor: a brief history.

In the 1930s, investigators in the US, Germany and Switzerland made the first attempts to quantify the course of labor in a clinically meaningful way. They emphasized the rupture of membranes as a pivotal event governing labor progress. Attention was also placed on the total number of contractions as a guide to normality.

Misguided guidelines for managing labor.

In a recent review we expressed concerns about new guidelines for the assessment and management of labor recommended jointly by the American Congress of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM). These guidelines are based heavily on a new concept of how cervical dilatation and fetal descent progress, derived from the work of Zhang et al. In their Viewpoint article they have addressed, but not allayed, the concerns we described in our review.

Perils of the new labor management guidelines.

Recent guidelines issued jointly by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine for assessing labor progress differ substantially from those described initially by Friedman, which have guided clinical practice for decades. The guidelines are based on results obtained from new and untested methods of analyzing patterns of cervical dilatation and fetal descent. Before these new guidelines are adopted into clinical practice, the results obtained by these unconventional analytic approaches should be validated and shown to be superior, or at least equivalent, to currently accepted standards.