Reasons for premature births a mystery.

• Position: Preterm Labor

In the 21st century, human tissue can be generated from stem cells and severed limbs routinely are reattached, yet the physiological processes governing life's most fundamental event, childbirth labor, remain a medical mystery. More than 500,000 babies, or one of every eight infants, are born prematurely in the U.S. The causes of 30-50% of preterm births are unknown.

"Identifying the molecular bases of changes in uterine muscle activity during pregnancy offers opportunities for rational drug design for the pharmacological treatment of preterm labor," notes Glenna Bett, assistant professor of gynecology and obstetrics in the University at Buffalo (N.Y.) School of Medicine and Biomedical Sciences.

"Therapeutic interventions that target earlier steps in parturition should prove more effective in delaying birth than currently used agents, which have only limited effectiveness. A fundamental problem in developing therapeutic interventions for preterm labor is that the molecular bases of the mechanisms involved in parturition are unknown."

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Uterine contraction, like all smooth-muscle contraction, primarily is an electromechanical event. Although hormonal and biochemical changes play a vital role in regulating and developing conditions leading to labor, the speed and coordination of a process called excitation-contraction coupling in uterine muscle tissue indicate that the short-term signals for contraction are carried by ion channels.

Excitation-contraction coupling is a term used in muscle physiology that describes...