Thinking ahead to your birth can be stressful. We moms and soon-to-be-moms tend to be planners, so the idea of this impending, hugely important, momentous event that we really can’t plan for can be kind of uncomfortable.

When will I go into labor?

What will labor feel like?

How am I going to cope with labor?

And of course, how long will labor last?

As a midwife, I try to be very “go with the flow, trust the process” about birth, but listen—I get it. As I mention here, I think the most stressful part of giving birth is not knowing how long it’s going to go on for. Especially when we are surrounded by people who care A LOT about how long it’s taking.

One minute of history: In 1959 a man named Dr. Emanual Friedman published his findings on how long a normal labor should last, defined by the rate a cervix dilates (opens). He essentially said that a woman should dilate 1 centimeter every hour.

His findings revolutionized the field of obstetrics. A chart called the Friedman curve was established, and accepted widely as the definitive guide to how well a labor was progressing—if a woman “fell off the curve” (a term still used in obstetrics today), it was time to start worrying that she was having a “dysfunctional labor” (another term still used today) and medical intervention was likely necessary.

The problem is that Dr. Friedman was wrong.

Essentially, his curve dictated that a woman needed to dilate faster than most actually do. In 2002, Dr. Jun Zhang found “that the pattern of labor progression in contemporary practice differs significantly from the Friedman curve. The diagnostic criteria for [slow]... labor may be too stringent in... women [having their first baby].”

In other words, we’ve been rushing women through labor.

Practice has been slow to change. I say that without criticism—I have definitely sat by a laboring woman’s bed, looking at the clock willing things to “pick up.” Because the truth is sometimes something is up, and we do need to intervene. And when the stakes are as high as they are in birth, we get, well, nervous.

But a new study confirms that we can actually relax and trust the process more.

Research lead by Dr. Olufemi T. Oladapo from the World Health Organization looked at 5,606 women with low risk pregnancies who had vaginal births with their first babies. The women all arrived at the hospital dilated at least 6 centimeters, with babies in the head down position. The researchers found that a first time mom can take as long as 7 hours to dilated from 4 to 5 cm and 3 hours to dilate from 5 to 6 cm.

In short, whoa.

Dr. Oladapo writes, “The average labour curves derived from our study population are substantially different from those published from the pioneer work of Friedman... [using] the...average labour curves could potentially misclassify women who are slowly but normally progressing as abnormal and therefore increase their chances of being subjected to unnecessary labour interventions.

“We propose that averaged labour progression lines or curves are not used for decision-making in the management of labour for individual women.”

In other words, every woman, pregnancy and birth is different and should be looked at on an individual basis, not as a mark on a chart.

So many factors can lead to a longer than average labor—fear, stress, medication, anatomy and position to name just a few. Every woman than walks onto the labor floor needs to be treated holistically. Her wants and desires, the big picture, the scientific evidence—it all matters.

This study does not mean that it always goes perfectly. Of course there are instances where interventions truly are necessary, and we are very glad that they exist.

Dr. Oladapo said it best. “In the absence of any problems other than a slower than expected cervical dilatation rate... during labour, it is in the interest of the woman that expectant, supportive and woman-centered labor care is continued.”