Vaginal delivery of human babies includes two often harrowing stages: "Stage 1" consists of "labor" to dilate the cervix, while "Stage 2" encompasses "pushing" the baby out through the vagina.

As far as I have found, the sole purpose of Stage 1 is to dilate the cervix, and this is typically accomplished solely by uterine contractions causing the baby's head to press against it. This seems like a very inefficient mechanism: the cervix begins entirely closed, and the baby's head is somewhat round and about 10cm in diameter. Indeed, debilitatingly painful labor often lasts for many hours.

Balloon dialation devices have been used since the nineteenth century to directly open the cervix during labor. It appears that the current obstetric practice is known as Foley bulb induction. But as far as I have found, such artificial dilation of the cervix is an exceptional measure, not a typical practice. Therefore:

  1. Does artificial dilation assistance (not induction) during Stage 1 labor pose a risk that natural dilation does not?

  2. Does Stage 1 labor have some beneficial function other than to dilate the cervix?

  • Your second link is broken. (Correction: Ad blockers can interfere with that link.)
    – Carey Gregory
    Commented Aug 3, 2021 at 0:02
  • 1
    @Lysander Turns out my ad blocker was somehow causing the article to be immediately replaced with a general landing page. I have no idea how an ad blocker could do that, but once I turned it off for that site, the article appeared.
    – Carey Gregory
    Commented Aug 3, 2021 at 19:18
  • @Lysander If you read my answer, Stage 1 is softening and opening of the cervix, so I cannot understand what you are asking in your edited question 2. Balloon dilation devices and Foley bulb induction devices are just that, induction devices. Commented Aug 4, 2021 at 8:19
  • @ChrisRogers – Cervical dilators can apparently be used to induce labor. The question is about using them to assist Stage 1 labor that has already begun.
    – Lysander
    Commented Aug 4, 2021 at 15:57
  • @Lysander That has been covered in the answer Commented Aug 4, 2021 at 15:58

1 Answer 1


Q1 - Does artificial dilation assistance during labor pose a risk that natural dilation does not?

You are not going to be able to insert a catheter into the cervix without risk of harming the baby or mother's cervix. Once labour has started, that risk is higher.

Your second link which talks about Foley bulb induction (along with induction methods other than balloon dilation) gives you the answer.

The end of your pregnancy can be an uncomfortable time. You may have back pain, trouble walking, or difficulty sleeping. If you’re past your due date, you may welcome an induction. But it’s important to understand the possible risks of labor induction, which include:

  • need for a cesarean delivery
  • drop in heart rate from labor-inducing medications
  • infection
  • umbilical cord problems
  • bleeding after birth
  • uterine rupture

Given the potential risks, your doctor can choose the safest induction method for your situation.

Q2 - Does labor have some beneficial function other than to dilate the cervix?

Labour is the whole process of giving birth, not just dilation of the cervix. Plus, you state there are 2 stages when in actual fact, there are 3 stages of labour

  • Stage 1
    The cervix softens making opening easier and contractions start opening the cervix. Established labour is when your cervix has dilated to about 4cm and regular contractions are opening your cervix.

  • Stage 2
    Giving birth to the baby - The cervix is at least 10cm dilated (fully dilated).

  • Stage 3
    "Afterbirth" (Expelling the placenta). After which, the midwife will need to check that the whole placenta is expelled to prevent further problems due to post-partum haemorrhage.

  • The question specifically pertains to "Stage 1." I edited the question to clarify that. The "risks of labor induction" described in the link do not clearly apply to balloon dilation, and at least one ("drop in heart rate from labor-inducing medications") obviously doesn't. The question is not about labor induction, but rather about the use of a balloon dilator to assist Stage 1 labor.
    – Lysander
    Commented Aug 3, 2021 at 17:47
  • 1
    @Lysander From what I've read you can't separate the two. Dilation induces labor.
    – Carey Gregory
    Commented Aug 4, 2021 at 15:06
  • At the beginning of Stage 1 labor the cervix is closed. The cervix is dilated to 10cm over the course of Stage 1 labor, which often lasts for hours. So the question is about waiting until labor has begun and then using a dilator to artificially open the cervix.
    – Lysander
    Commented Aug 4, 2021 at 15:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.