Length of Labor Longer Than 50 Years Ago

by Cassandra R. Elias

Length of Labor LongerWomen take longer to give birth today than women 50 years ago, according to an analysis of nearly 140,000 deliveries conducted by researchers at the National Institutes of Health.

First-time-moms in the early 2000s took 2.6 more hours to progress to full dilation when compared with those giving birth in the early 1960s. For moms who had previously given birth, this early stage of labor took two hours longer in recent years than for women in the 1960s.

How does this data affect you and your birth? It could mean your healthcare provider will wait longer before suggesting an intervention.

Study Results

Comparing contemporary labor trends with labor 50 years ago, researchers sound several differences:

Babies arrived earlier and were bigger: On average babies in the contemporary group were born five days earlier and tended to weigh more.

Overall labor is longer: Labor averaged 2.6 hours more for first-time moms and two hours more for moms who already had given birth

Active phase of labor occurs later: Women in the 50s gradually progress on a curve with a more rapid increase in dilation occurring from 5.5 centimeters on. The analysis of recent births suggests that labor doesn't accelerate until later, around 6.5 centimeters.

Labor practices have changed: More mothers are induced or use epidurals. Both have been shown to be associated with longer labor.

More babies were born via c-section: 12 percent of first-time-moms in labor gave birth by c-section compared to 3 percent in the 60s.

Reasons Why Labor Longer Today

While modern moms might have many reasons why labor lasts longer, two known characteristics of moms today are known to lengthen labor. These are an increase in BMI and older maternal age.

"Older mothers tend to take longer to give birth than do younger mothers," said the study's lead author, S. Katherine Laughon, M.D., of the Epidemiology Branch of theEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).

Taking these factors into control doesn't completely explain the difference in labor times between now and then. Among the changes in delivery practices the researchers discovered an increase in the use of epidural anesthesia, the injection of pain killers into the spinal fluid, to decrease labor pains.

For the contemporary group, epidural injections were used in more than half of recent deliveries, compared with 4 percent of deliveries in the 1960s. The study authors noted that epidural anesthesia is known to increase delivery time on average from 40 to 90 minutes, but said it doesn't account for the increased length of labor.

Other differences between the two groups reflect changes in later stage delivery practices. For example, in 1960s-era deliveries the use of episiotomy (surgical incision to enlarge the vaginal opening during delivery), and the use of forceps, surgical instruments used to extract the baby from the birth canal, was notably more common.

In current practices, doctors may intervene when labor fails to progress. This could happen if the dilation of the cervix slows or the active phase of labor stops for several hours, Dr. Laughon explained in NIH's press release issued March 30, 2012.

In these cases, intervention can include administering oxytocin or performing a cesarean delivery.

This study didn't examine all of the practice patterns such as how mothers in earlier studies could have been up and walking more than women do today, whose activity is limited once they've received an epidural.

Will These Findings Change OB Practices?

Clinicians are using a definition of abnormal labor that is from 50 years ago. Today, women labor longer and begin active labor at a later point in dilation.

The authors of the NIH study note in the press release that while their study doesn't identify all the factors contributing to longer delivery times, the findings do indicate that current delivery practices may need to be re-evaluated. They suggest that the timeline for when to intervene with pitocin or to order a cesarean should be updated to reflect the current findings.

Dr. Laughon says, "We found a lot of c-sections ordered because of failure to progress. According to our findings many of these occurred before women got into active stage of labor."

She says that women who are motivated to have a natural labor and delivery, can feel more comfortable asking for more time if labor is going slowly.

D. Ware Branch, a Maternal-Fetal Medicine specialist with Intermountain Healthcare, chimed in, "Well-informed women who prefer a natural birth, might want to seek out care givers who are familiar with modern labor pattern that favor vaginal delivery when safe."

Doctors in the early 2000s also administered the hormone oxytocin more frequently (in 31 percent of deliveries, compared with 12 percent in the 1960s), the researchers found. Oxytocin is given to speed up labor, often when contractions seem to have slowed. "Its use should be expected to shorten labor times," Dr. Laughon explained. She continued, "Without it, labor might even be longer in current obstetrics than what we found."

Medical references:
Laughon, S.K., Branch, D.W., Beaver, J., Zhang, J., Changes in
labor patterns over 50 years, American Journal of Obstetrics and Gynecology (2012), doi: 10.1016/j.ajog.2012.03.003.

The study compared data from nearly 40,000 deliveries between 1959 and 1966 with records of almost 100,000 deliveries that took place in 2002 through 2008. Data from the recent deliveries were collected through the NICHD-supported Consortium on Safe Labor.

Dr. Laughon conducted the study with D. Ware Branch, M.D., of Intermountain Healthcare and the University of Utah, in Salt Lake City; Jun Zhang, Ph.D., M.D., with the NICHD at the time of the study and now with the Shanghai Jiaotong University School of Medicine, China; and Julie Beaver, M.S., formerly with the NICHD.