As OB-GYNs will tell you, in order to give brith, your cervix first has to begin dilating. So when looking for signs you're dilating, you're often at a stage where you feel ready to have your baby or think you might be approaching labor. But in order to know the signs, you have to understand dilation and your cervix.
According to BellyBelly, the cervix plays a crucial role in pregnancy and labor, as it is supposed to remain closed and hard to protect your uterus from outside bacteria. During pregnancy, however, it begins to "ripen" and thin (often referred as effacement at your appointments), and will eventually begin to dilate as you near labor and start experiencing contractions. Because the opening to the cervix is sealed by the mucous plug, according to What To Expect, you could lose your mucous plug as you continue to dilate and your cervix thins. (It's worth nothing that this is different from your water breaking.)
Dilating is different for every woman. With my first baby, I was between 4 and 5 centimeters dilated a good week or two before I went into labor. For other women, however, they could easily only be 1 or 2 centimeters dilated when they hit labor or get induced. Although experiences may differ for each mom, dilation is still closely coordinated with labor, or at the very least, your body preparing for labor in the weeks to come.
Aside from getting an update from your doctor at your pregnancy check ups, you can also check out some of the signs highlighted below that may let you know you're dilating.
According to the aforementioned BellyBelly article, mild or irregular contractions can contribute to dilation. Although contractions are often the direct result of your body preparing to go into labor, there's no need to be alarmed or assume you're in active labor until you're having consistent contractions that are starting to feel stronger and happening closer together.
If you lose your mucous plug, which is usually a slimy, brownish substance, it's a solid sign your cervix is thinning and dilating. Losing your mucous plug is not the same as your water breaking, so there's no need to panic. It can happen anywhere from a couple weeks to a couple hours before labor.
Although I can imagine that it's not advised, Babble shared you can tell if you're dilating by simply being able to slip your fingers into the cervix opening up in your vagina. Although it may be a difficult spot to reach, if you're able feel a cervix opening, it should feel like putting your finger between lips, and you may even be able to feel your baby's head in the amniotic sac.
According to Healthline, dilation generally occurs in a very predictable way as you progress into labor stages at the end of pregnancy and during labor especially. You'll start by dilating 1 centimeter, which is the equivalent of a blueberry, and end at 10 centimeters dilated, or the size of a bagel.