What happens during labor? Your uterus contracts. And what is the purpose of those contractions? To open your cervix.
Well yes, but no. Contractions are less about a hole opening up and more about a muscle being built. Stay with me, here. I’ll explain. Let’s start with the fundus. The official definition of fundus is “the part of a hollow organ that is farthest from its opening.” So the fundus is the top of the uterus, farthest from the opening, the cervix, at the bottom. Got it? Good. Now, the uterus is an organ made up of muscle fibers. It is a big mass of muscle fibers all crisscrossing over and under and between each other; some running up and down and some running around it side-to-side. During a contraction, these muscle fibers…..well, they contract, pulling the cervix up and out causing the cervical tissue to thin and then open. As this happens, these muscle fibers start building up at the top of the uterus, the fundus. They are slowly moving from the bottom of the uterus, to the top with each contraction. As they do so, the cervix thins and opens at the bottom while the fundus is thickened and strengthened at the top of the uterus. And with each contraction, the fundus pushes down on the baby. As the fundus gets bigger, the push gets stronger. Once the cervix has finished opening, the fundus has also finished growing and now is a very large, very strong muscle that expels the baby from the uterus.
Pretty cool, right?
Let’s not stop there, though. Let’s talk a bit about pushing.
But, let’s do it Tuesday. I’ll see you back here Tuesday.
*Updated to add links to Part 2 and Part 3
Amber Piller - Professional Birth Doula and owner of Agape Birth Services. Serving Northwest Houston including Jersey Village, Cypress, Tomball, Spring, and Katy Texas.