Many things can be done faster now than 50 years ago, but the arrival of a baby into the world naturally seems to be one of them, according to a study by the Government of the United States .
Compared to the 60's, American women have passed in recent years two or three hours in labor , according to researchers at the U.S. National Institutes of Health , who said the finding suggests that physicians may need to rethink the definition of what a labor "normal".
According to data published in the American Journal of Obstetrics & Gynecology, the extra time comes from the first stage of labor, the longest part of the process before the stage of "push".
Mothers are also different. On average, they're bigger and heavier, and their newborns are also larger.
"But even when we consider these demographic changes, labor is even longer," said lead researcher Katherine Laughon, National Institute of Child Health and Human Development.
Although Laughon said the study could not fully identify the possible reasons for the differences, one explanation could be partial pain relief from epidural anesthesia, which is much more common now than 50 years ago.
It is known that epidurals can slow labor between 40 and 90 minutes .
The data are based on two government studies conducted in different decades.One, between 1959 and 1966, included some 39,500 women who gave birth to a baby to term, while the other tracked more than 98,000 women who gave birth at term between 2002 and 2008. All women had a spontaneous labor, ie was not induced.
As regards the duration of labor, new mothers in recent years it takes 2.6 hours more in the first stage, compared with their counterparts in the 60's. This difference was reduced to two hours in women who were already mothers above.
Today women were much more likely to use epidural anesthesia: 55%, compared with 4% of 50 years ago .
12% had a cesarean delivery compared with 3% in the 1960's, while 31% was applied oxytocin, which stimulates contractions, compared to 12% from 50 years ago.
Laughon said that many more women now have induced labor or planned cesarean section compared to decades ago, so the number of women who currently have a spontaneous labor may differ somewhat from their counterparts 50 years ago .
But whatever the underlying reasons, doctors may need to redefine the idea of a labor "normal" , a concept based on what was the norm for women half a century ago.
For example, doctors have found that a labor is abnormal if there is no change in the cervix after two hours in the "active" in the first stage of labor. At that time, may intervene either by administering oxytocin or by cesarean section.
Laughon said that the conclusion is that there would be a new concept of "normal" , adding: "I think we need to revise the definitions of 'abnormal' and labor and the right time for the interventions we use."