What causes membranes to rupture?

[NorthernPixie]

Is this known? What I mean is, is it something chemical released by the mom's body or the baby's body that causes a weakness in the sac and it breaks? Is it physical/mechanical wear, i.e. pressure of head on cervix wears a hole in the sac? Something else entirely, or for causes unknown? I'm an admitted science geek and am just curious!

[cinderella08]

Good question!! Wish I knew the answer for ya!

[HeatherB]

Good question! It does seem that the final "blow," as it were, is often physical movement by the baby - a kick or head-butt or something along with which there's a "pop." I also know that some say taking vitamin C in pregnancy and/or 3rd tri can strengthen the sac. Conversely, there may be deficiencies which could cause a weaker sac. Just hypothesizing, but I'm very curious if any birth pros have more details on it.

[Harmony96]

DD's water broke when I had a contraction on the toilet, so I imagine the contraction squeezed it open.

DS's water broke while I was sitting on the bed (also after several hours of labor), with seemingly no movement from him and no contractions or anything. It was just all of a sudden quietly flowing out, lol.

[MammaB21]

This is a really good question. I always figured it was a combination of things. We know that there are chemicals released into our bodies which stimulate labor to begin. So maybe those chemicals weaken the sack. That would explain why some women experience PROM with no immediate onset of labor. Perhaps in a sack that is already weak the hormones alone are enough to rupture them?

But I think in general, most women experience ROM during active labor. I think it typically takes a combination of the hormones and the contractions and downward pressure of labor. The baby's moving down and pressing up against the cervix with the bag of water between the cervix and their head. Couple that with a contraction and I think you have enough to rupture the membranes. But I'm totally guessing on all of this.

In DD's labor, my water didn't break until right as she was coming into the birth canal and moving to the crowning position. I was on the toilet and the water broke in one big swoosh/gush. It had been bulging out and felt like a softball was falling out of me. In DS's labor my water broke while I was side lying in bed during a contraction in early labor. It was after many hours of early labor but the contractions were still far apart and totally manageable. I felt a tiny pop and no gush followed. From then on out I only felt little gushes when I would walk around. Two totally different experiences and it really makes me wonder what exactly causes them to brake.

[RedOakMomma]

I'm not sure what it is, but I suspect it's genetic. Both of my mother's two labors started not with contractions, but with her water breaking. With me it's been the same--two labors, no contractions, just my water breaking. Both times I was bending down to pick something up, and only in the second one did I feel any kind of punch/pop.

I've taken vitamin C since the second trimester to try to strengthen my amniotic sac with this pregnancy (only because I was worried about p-ROM), but as I got closer to term I stopped.

To be honest, I won't know what to do with myself if my labor starts with plain old contractions! I'm used to my water breaking, then having a good half day of twiddling my thumbs while I wait for labor to start!