The Conventional Wisdom On How Long 'Normal' Labor Takes Is All Wrong

Catherine Pearson
(Photo: RyanJLane via Getty Images)
(Photo: RyanJLane via Getty Images)

In the 1950s, an American obstetrician by the name of Emanuel Friedman began publishing studies that fundamentally changed how childbirth was managed in the United States.

Friedman was the first to define the various stages of childbirth, and he established the idea of a “normal” labor curve, plotting it out on a graph. Once labor begins, the cervix — which must open and thin before a vaginal delivery — should dilate at least 1 centimeter per hour, he said.

For years, that expectation has shaped clinical practice. And for years, everyone from midwives to self-appointed “natural birth” advocates have railed against Friedman’s benchmark, arguing that it incorrectly treats as abnormal any labor that does not hew to this rigid, somewhat arbitrary pattern.

Increasingly, science aligns with the critics.

This week, a study that looked at outcomes for more than 5,000 women in 13 hospitals in Nigeria and Uganda found the average rate of dilation in women in spontaneous labor — and who ultimately delivered without complications — was slower than 1 centimeter an hour until they were 5 centimeters dilated. That was true whether it was their first labor or fifth.

Some women in the study took more than seven hours to dilate from 4 to 5 centimeters, and more than three hours to go from 5 to 6 — well outside of what is considered “normal” based on Friedman’s standards. Yet they and their babies were healthy.

“Cervical dilatation progression during active labour is not linear,” study author Olufemi Oladapo, a maternal, perinatal and newborn health research and public health expert with the World Health Organization, wrote in an e-mail to HuffPost.

“The rate of progression varies from one woman to another and women tend to enter their phase of natural labour acceleration at different times,” he continued.

The new study out this week is not the first to argue against traditional labor curves — nor does it specifically tackle the question of how they might contribute to the growing C-section rate — but it adds to the growing body of literature pushing back against that standard worldwide. It is the first to show women in Africa, like women elsewhere, take more time to labor than previously thought, Oladapo told HuffPost.

In the United States, roughly 1 in 3 women who give birth do so via cesarean section, making it the most common surgery performed in the country today. In some cases, C-sections are absolutely necessary and life-saving. But in others, doctors who recommend a C-section have deemed a labor risky simply because it is taking too long. Indeed, slow labor is the most common reason given for a woman’s first C-section — and women who have one C-section are more likely to go on and have another.

In 2014, major American medical groups — including the American College of Obstetricians and Gynecologists — issued official guidelines that specifically challenged Friedman’s standards.

Broadly speaking, slow progress in the first stage of labor should not be a reason for performing a C-section, the guidelines state, and a woman shouldn’t be considered to be in active labor until she is 6 centimeters along.

“We generally want moms to be 6 centimeters for up to six hours before we say there’s an arrest of dilation where they’re not actually dilating,” Dr. Lisa Levine, a maternal fetal medicine specialist with Penn Medicine, told HuffPost. “If in that six hours, they’ve changed two or three centimeters, that’s still enough that we still proceed with things.” Levine cautioned, however, that it is not yet clear whether the new guidelines have actually decreased C-section rates nationally or improved outcomes for women and babies.

Meanwhile, however, Friedman’s standards continue to circulate, and standards of care in medicine can be slow to change.

Globally, medical students and midwifery students are still taught the 1 centimeter per hour benchmark, and the World Health Organization recommends the use of the “partograph” — a chart used to document the course of a normal labor, based on Friedman’s concepts — to manage labors worldwide, Oladapo said. Levine agreed that it is the “textbook answer” expected in medical school, though she believes that in the United States at least, that has changed in the last several years.

“On the wards, when students are with us and learning hands-on, we go over the fact that this is not actually how we manage women,” said Levine. “I think it’s slowly getting phased out.”

Also on HuffPost

1. Your Blood Volume Increases

During pregnancy, the volume of blood in a woman's body increases by a whopping 50 percent in order to help support the uterus. Accordingly, the amount of blood pumped by the heart increases as well. As the <a href="http://www.merckmanuals.com/home/womens_health_issues/normal_pregnancy/physical_changes_during_pregnancy.html" target="_blank">Merck Manual explains,</a> by the end of pregnancy, a woman's uterus receives one-fifth of her pre-pregnancy blood supply.

2. You Actually Glow

If you find yourself looking all dewey and glow-y during your pregnancy, it's not just because you're brimming with I'm-about-to-become-a-mom sentiment; there's also a physiological basis for it. The aforementioned increase in circulation that occurs during pregnancy causes many women's faces to appear brighter, or flushed. And, as the <a href="http://americanpregnancy.org/pregnancyhealth/skinchanges.html" target="_blank">American Pregnancy Association reports</a>, as women's bodies produce more hormones, their oil glands can go into overdrive, resulting in that famed pregnancy glow.

3. You Grow An Entire Organ

During pregnancy, women's bodies grow a <em>whole new organ</em>, i.e., the placenta -- a structure that develops in the uterus and provides oxygen and nutrients to your growing baby (while also playing a key role in waste removal). The organ typically grows onto the upper part of the uterus and is linked to your baby via the umbilical cord. After your baby's born and the placenta's job is done, it is simply expelled through the birth canal (although some women, including a growing number of celebs, then ingest it for its reputed health benefits -- a practice known as <a href="http://www.huffingtonpost.com/mark-b-kristal/placenta-to-eat-or-not-to_b_1865446.html" target="_blank">"placentophagia"</a>).

4. You Loosen Up

More specifically, as you move through your pregnancy, hormones (especially the aptly named "relaxin") help soften the ligaments that hold your bones together and the pelvic bones themselves begin moving to accommodate your baby's birth. Sometimes, this can cause a bit of pain and discomfort (if it's severe enough, you should see your doctor), although as <a href="http://www.whattoexpect.com/pregnancy/ask-heidi/pelvic-pain.aspx" target="_blank">What To Expect reports</a>, once your baby is born, your joints will firm up again.

5. You Stop Shedding

Do you have the thickest, most amazing head of hair, like, ever? During pregnancy you stop shedding hair at it's normal rate. <a href="http://www.babycenter.com/0_hair-and-nail-changes-during-pregnancy_1456563.bc" target="_blank">As Baby Center explains</a>, most of the time between 85 and 95 percent of the hair on your head is growing, while the rest is in a "resting" stage, before it falls out. But during pregnancy, higher estrogen levels extend that growth phase, meaning you lose less hair and may suddenly find yourself with a gloriously thick ponytail. (Although, <a href="http://www.huffingtonpost.com/2013/07/31/post-pregnancy-body_n_3659565.html" target="_blank">as we previously reported</a>, after your baby's born, that "extra" hair will fall out.)

6. You Breathe Differently

It's not uncommon for pregnant women to feel short of breath, particularly later in their pregnancy when the uterus grows and begins to press on the diaphragm. But breathing also changes because of the high levels of the hormone progesterone in your body signal your brain to lower the levels of carbon dioxide in the blood, <a href="http://www.merckmanuals.com/home/womens_health_issues/normal_pregnancy/physical_changes_during_pregnancy.html" target="_blank">Merck explains </a>-- yet another amazing example of all the things your body does to support and accommodate a growing baby.

7. You Become Particularly Orgasmic

<a href="http://www.babble.com/pregnancy/5-things-you-might-not-know-about-orgasms-in-pregnancy/" target="_blank">As Babble explains</a>, the increased blood flow to a woman's genitals -- plus the general surge in any number of hormones that influence desire -- can make many pregnant women feel libidinous. And those changes can also increase sensitivity, allowing many women to orgasm more easily. But as with all things related to sexuality, this is totally individual -- some women want nothing to do with sex while they're pregnant.

Love HuffPost? Become a founding member of HuffPost Plus today.

This article originally appeared on HuffPost.