How This Weird Purple Line on Your Booty Might Reveal When Your Baby's Coming

When it comes to giving birth, knowing how dilated you are can make or break your morale. Maybe you find out you're even more dilated than you thought, and you're impressed with how much pain you can actually take. Or you're kinda slow to dilate, and you're like, "OMG, get me the drugs." Either way, it's important info. But having invasive exams to see how far along you are is also majorly uncomfortable. Turns out there's a rather unconventional physical sign that can offer women an alternative way to check dilation -- without the dreaded vaginal exam.


According to a popular post on the Birth Without Fear blog, some women actually develop a dark purple "dilation line" that shows up and extends along your natal cleft, aka your butt crack. It starts at the anus and moves up the cleft. Apparently, when it's all the way to the top, you're 10 cm dilated.

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This photo from Instagram, posted by midwife Lindsey Meehlis, depicts the phenomenon. 

purple line natal cleft

The line has been a popular indicator of progress in natural birth circles for a long time. Birth Without Fear even cites research published by BMC Pregnancy & Childbirth that states the line itself is present at some point in labor for 76 percent of women. It's more apt to show up in women with spontaneous labor than in those with induced labor (80 percent vs. 59 percent), and the further dilated a mom-to-be is, the more likely it is the line will appear. In the research, the line seems to first show up for most women when they're around 3–4 cm. So interesting!

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That said, is this really something that your ob-gyn will put any stock in? Not so much, according to Kecia Gaither, MD, a double board-certified physician in OB/GYN and maternal fetal medicine. "Any hyperpigmented areas along a woman's body during pregnancy are likely due to hormonal influences, which resolve shortly after resolution of the pregnancy," Dr. Gaither notes. "To my knowledge, there is no scientific correlation between the degree of hyperpigmentation between the buttocks -- natal cleft -- of a pregnant woman and her labor progress."

Midwives and doulas may be more likely to take a peek at the line, but they acknowledge it's not exactly the most scientific way to figure out how close you are to welcoming your LO.

"I have witnessed the phenomena of the purple line during labor, and it is quite an interesting sight," says Jennifer Mayer, certified holistic health coach, birth doula, and cofounder of Baby Caravan in New York. "At some births -- mainly home births -- if everything is unfolding smoothly and with no complications, the midwife might refrain from performing any vaginal exams at all. The purple line could be used as a gentle indicator of where the birthing person is in their labor -- though not as the sole source of information if a medical decision had to be made."

Ultimately, it's "an outside guideline of where a birthing person is in their labor," Mayer notes.

In other words, the purple line's far from the be-all and end-all of exams to facilitate a smoother birthing process. But is it a less invasive way to offer your health care provider a bit more info about your progress? Sure. And when it comes to bringing a new little human into the world, who wouldn't want all the help they can get?

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