New York, March 19 (IANS): Maternal cardiac arrest, which means that the mother's heart stops beating either before or after childbirth, may be two times more common than previously reported, research shows.

The study, based on data for more than 56 million births, also found that the survival rate improved in US between 1998 and 2011.

A number of health issues that may occur during childbirth can lead to cardiac arrest, including excessive bleeding, heart failure, heart attack, preeclampsia, blood infection and amniotic fluid embolism, where amniotic fluid enters the mother's bloodstream.

These issues can cause irregular heart rhythms, or reduced blood flow and oxygen to the heart (heart attack); either problem can cause cardiac arrest, the research showed.

"These are rare high-stakes events on obstetric units, and team preparation is critical to ensure that everyone is ready to act quickly and effectively," said Jill M. Mhyre, associate professor of anesthesiology at the University of Arkansas for Medical Sciences.

Using data from the US government's Nationwide Inpatient Sample - the largest all-payer inpatient health care database in the US - researchers identified 4,843 cardiac arrest events among 56,900,512 hospitalisations for childbirth, a rate of one in 11,749.

The main causes of cardiac arrest included bleeding (44.7 percent), heart failure (13.3 percent), amniotic fluid embolism (13.3 percent) and blood infection, or sepsis, (11.2 percent).

"This information will assist health care providers to deliver the most effective maternal cardiopulmonary resuscitation (CPR) when both the mother's and baby's lives are on the line," Mhyre said.

The study appeared in the journal Anesthesiology.