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Labor and delivery

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Nauroz Syed.

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Video transcript

- [Voiceover] I thought the movies taught me everything I needed to know about labor and delivery. The water breaks, mom yells, everyone rushes in to the hospital, and after a few breathing exercise and two or three really hard and loud pushes, the baby arrives. Well, reality couldn't be further from that. For one thing, most of the time, labor is preceded by a few signs that tell the mom that the baby is about to come. One of those signs is lightening. One of those signs that tells the mom that the baby is about to make his or her debut is lightening or people like to call the drop. And what it refers to is the baby's head engaging with and sort of settling into mom's pelvis which the mom can feel. It feels like the baby is sitting lower in the abdomen and this is my sort of diagram depicting that. So I don't know if you can tell but this is the pelvis and this here, this here is the baby. And you can see that the baby's head is sort of nestled into and settled into mom's pelvis. And that's called lightening. Another one of those signs that tells mom that baby is about to come is Braxton Hicks contractions. They're called Braxton Hicks contractions sometimes called practice contractions, and that's exactly what they are. They're uterine contractions that occur as early as the first trimester. But unlike real labor contractions, they're infrequent, they're irregular and they don't occur with a pattern. As delivery approaches, Braxton Hicks contractions tend to become more frequent and they tend to become more uncomfortable. And then another big sign of impending labor is loss of the mucus plug which the mucus plug is the mucus that seals the opening to the cervix. So it seals the endocervical canal. The canal that's inside the cervix. And when the cervix loosens up and it dilates during labor, the plug falls out. And sometimes when that mucus plugs is blood-tinged it's referred to as the bloody show. It's referred to as the bloody show. I always wondered what that was, the bloody show. Okay, so those are some of the signs of impending labor but what on earth is labor? Well, labor is when you have regular uterine contractions that lead to changes in the cervix, in the passage of the baby. So the contractions have to be regular. They have to be patterned and they have to lead to some change in the cervix, and that's what labor is. And we split labor up into three distinct stages with each stage kind of having its own goal. There's the first stage of labor. So there's the first stage of labor, the second stage of labor, second stage of labor, and the third stage of labor. And we're gonna go through each of these stages independently starting with the first stage of labor, which is the longest stage of labor. The first stage of labor is all about the cervix becoming fully dilated. And what that means, what it means for the cervix to become fully dilated is that the cervix goes from being thick and completely shut to thinning out and opening up 10 centimeters. 10 centimeters is what we call completely dilated. And that's a lot of change, right? It doesn't happen all at once instead it happens in three distinct phases. The first stage of labor has three phases to it. And the first of those phases is called the latent phase. The latent phase, right? During the latent phase, contractions become stronger, they become more frequent and more regular. And most of what's happening during this phase is the thinning or the effacement of the cervix. That looks something like this. You can see the cervix is becoming thinner, right? Not too much dilatation is occurring. In fact at most, the cervix will become three centimeters dilated max during this phase. This phase, the latent phase is actually the most variable phase from woman to woman. For a woman who's had kids before we expect it to last anywhere from 10 to 12 hours but for a woman who's having her very first baby, it can take as long as 20 hours. So that's a lot of variability. Okay, so we hope that by the end of the latent phase the cervix is maximally thinned out so that during the next phase which is called the active phase, the active phase, we can focus on the dilatation of the cervix, right? During the active phase, the cervix goes from being two to three centimeters dilated to becoming eight to nine centimeters dilated. It sort of looks like this, right? You can see that the cervix is becoming dilated or the space is increasing. And this phase is what you can call the most predictable phase of labor. It's so predictable that we measure it to rate. By that I mean that in a first time mom, the cervix has to dilate at least 1.2 centimeters per hour and that's in a first time mom. And for a mom who's had multiple kids in the past, the cervix has to dilate quicker so at least 1.5 centimeters an hour. It's that predictable, that predictable that we have this rate for it. So much so that if the cervix isn't dilating at the rate that we expect it to, we get really concerned. That leaves us with the last phase which is called the deceleration. The deceleration phase which some people like to call the transition. Transition, so the deceleration phase and transition are two interchangeable terms for this phase. During this phase, the cervix continues to dilate but more slowly than it did in the active phase. In some women, this isn't as much a separate phase as it is kind of an extension of the active phase. So it kind of blends in with the previous phase. Also the baby passes lower into the pelvis and deeper into the birth canal during this phase. Okay, so now we have a fully effaced, right, so fully thinned out and a fully dilated cervix. The second stage of labor marks the period between when you have a fully dilated cervix to the delivery of the baby. For a lot of people, this is what's known as the pushing stage. And usually, usually, this should take less than an hour in a woman who's done it before and less than two hours in a first time mom. But keep in mind that the use of something like an epidural can prolong this stage so it slows things down. Okay and then finally the final stage is stage three which is the period between the delivery of the baby and the delivery of the placenta, and this shouldn't take any longer than 30 minutes. So I hope that this has taken out some of the mystery out of what normally occurs during labor. But what about when things don't occur normally? What about when labor isn't progressing as quickly or as effectively as it should? Well if that's the case then we need to evaluate the three P's. If labor isn't progressing the way that it should we evaluate the three P's. The first P is powers, right? The first P is powers. The second P is passenger. Passenger. Have powers, passengers. And the last P is passage. So the three P's, powers, passenger and passages is what we sort of evaluate if labor isn't going the way that it should, if it's abnormal. Powers, the first P refers to uterine contractions or more specifically to the force that's generated by the uterine muscles when they contract. If there is an abnormality during labor, we have to ask ourselves, is it because the uterine contractions aren't occurring frequently enough? Are they not lasting long enough? Or maybe are they not strong enough? And we can assess that simply through observation. Typically we think that during active labor, we should have about three to five contractions every 10 minutes, right? We should have three to five contractions every 10 minutes. With each contraction lasting somewhere between 40 and 60 seconds, and each contraction being strong enough that the uterus feels firm when you palpate it, when you touch it. Or if you prefer to use more objective measure there are these devices called intrauterine pressure catheters that you can actually insert through the vagina and onto the uterus that will give you a numerical measure. So a more objective measure of how strong each contraction is. Either way, we know that contractions during labor have to be adequately frequent and adequately strong to achieve labor. And if they are not, we can use a drug such as oxytocin. There is this drug called oxytocin which causes the uterus to contract to sort of help us along. And you also have to think about the second contributor to powers and that's the bearing down efforts of the mom, and you have to think about if those are strong enough. If the mom is sort of pushing effectively and strongly enough. Okay, so if powers isn't the problem then we need to consider the second P, passenger which the passenger is of course the fetus. Some things to consider about the fetus include what its orientation is. Whether the head, the feet or the shoulders are delivering first, right? Because that can affect thing. We have to consider whether the head is flexed or whether it's extended, and of course how big the fetus' head is is also important to think about if you're having any abnormality in labor. And then finally there's a last P or passage which refers to mom's sort of bony pelvis and the soft tissues of the birth canal. So the cervix and the pelvic floor muscles, right? Abnormal labor could be the result of something we call cephalo, something we call cephalopelvic, cephalopelvic disproportion. Abnormal labor can be the result of cephalopelvic disproportion. Cephalo means head. Pelvic refers to pelvis, right? So we're talking about a disproportion between the baby's head and the mom's pelvis. Basically, the baby's head can't fit through mom's pelvis either because baby's too big or mom's pelvis is too small. In either case, since you really can't change either variable, C-section tends to be the only sort of treatment for this problem. All right, so that's a brief, very brief overview of labor. Hopefully the next time you see a Hollywood delivery you'll appreciate exactly how much they're leaving out.