Spotlight on the terms used to describe various points of the birthing process.

I imagine when one starts researching labor and birth for the first time, it can be daunting to make sense of all the terms describing the various stages and phases. The terms tend to be used rather inconsistently, which makes things even more confusing. Phrases like first stage, latent phase, active phase, transition, second stage, and third stage have very specific definitions; however, various sources and different people often do not mean the same thing when they use a given term (Menard 2014). And then there is the often-neglected experience of the birthing person; including, the relevance of these terms and distinctions to the person actually going through labor and birth.

The start of labor is the point when uterine contractions begin to change the cervix (Menard 2014). This cervical change can be softening of the cervix, thinning of the cervix (effacement), moving of the cervix forward (before labor and even in early labor, the cervix is located further back), and dilation (opening of the cervix). This start of labor is also the start of the first stage. Early labor is often the time during which the baby engages (the presenting part, usually the head, moving into the inlet of the pelvis), if this has not yet occurred. The first stage of labor is demarcated by the beginning of cervical change and is thought to complete once the cervix is fully dilated. Please refer to the image bellow to visualize the cervix and imagine how it may change throughout your birth. Though the initial cervical change is often accompanied by irregular contractions that feel like light menstrual crams, the signs of early labor can vary. Some people are not aware of their uterine contractions until they are quite close to being completely dilated, while others have painful contractions that do not seem to change the cervix for days. Moreover, some people will have very slow cervical changes over days or even weeks before the contractions become noticeable.

Image result for pregnant uterus cervix
Anatomy of pregnancy

What all this means is that the start of labor is very variable and difficult to pinpoint and standardize. From the perspective of the birthing person, the start of mildly painful contractions is the most meaningful determination for the start of labor. This distinction may not match the clinical definition, but is nonetheless important because once the birthing person begins to notice a change in the pattern and potency of their contractions, they become aware that labor has begun and start to exert energy to cope with what they are feeling. The sensations that come up for people vary widely; hence, how well someone copes at a particular point in the birthing process will be very individual.

If someone is experiencing painful contractions without detectable cervical change, this is often referred to as false labor or prodromal labor in the hospital. However, in home birth, this is seen as warmup. Same as stretching and warming up one’s body before exercise is not the actual workout, but can be necessary to prepare for the actual workout, so is labor warmup, and some will need more warmup than others. The duration and intensity of the warm up contractions is thought to relate to the relationship of the baby and the pelvis; meaning, how the bones, joints, muscles, and ligaments of the pelvis affect baby’s position and journey through the pelvis. Some babies need more contractions to help them get in position and engage. Occasionally, the laboring person may require some targeted positions or exercises to facilitate optimal fetal positioning. It is hard to say exactly why each birther and baby dyad has such a unique journey, but what is important to keep in mind is that all the elements have value and are required for that pair to work toward birth.

When labor is depicted in movies and shows, it always starts with the water-bag breaking; then, strong regular contractions immediately follow. This is actually pretty uncommon, most people will start noticing labor contractions well before their water-bag releases. Only 8% will notice their water releasing before contractions (ACOG, 2020). In cases where the water-bag releases before contractions, the contractions may not start for some hours or even days. However, about 76% of those people whose bag released before the start of contractions, will go into spontaneous active labor (labor that starts on its own without induction agents) within 24 hours of their waters releasing and about 90% will start active labor within 48 hours of waters releasing (Pintucci, 2014).

The first stage of labor is comprised of three phases. These three phases are latent, active, and transition. Throughout the three phases, the cervix typically opens from closed to complete dilation. The reported measurements range from 0cm to 10cm, but in reality, complete dilation just means that there is no more cervix over the presenting part (which is usually the baby’s head), rather than an exact 10cm diameter. The latent phase is often referred to as early labor and starts with contractions that are beginning to change the cervix. Typically, this exact start of labor is unknown because people usually do not have their cervix examined at frequencies required to make this determination. Moreover, determining the exact start of labor has no importance.

The latent phase gives way to active phase when the rate of cervical dilation starts to increase appreciably, so active labor starts when the cervix demonstrates an abrupt increase in the rate of dilation (Menard 2014). Clinicians often site a singular cm dilation as the start of active phase for every birther; however, this is not accurate (Cohen 2015). The start of active phase occurs at a different cm dilation in different people. The currently touted 6cm dilation as the start of active labor misses people’s individuality. The research, based on which 6cm came to define active labor, actually demonstrated that by 6cm dilation, 95% of birthing people have reached the active phase (Neal 2015). Hence, the start of active phase for most birthers occurred at some point before they reached 6cm. Additionally, progressive cervical dilation should be accompanied by the baby rotating and moving lower in the pelvis. The measure of how low the baby is in the pelvis is called station, and it is arguably even more important than dilation because if the baby is descending through the pelvis, the cervix will eventually dilate; conversely, the cervix can be completely dilated, but the baby can remain high in the pelvis. Finally, whether a station is high or low is relative to the stage of labor, early in labor the baby can be at -1 and 0 station is quite low, but in transition +1 is a good sign.

The dilation and station are assessed when a cervical exam is performed. In fact, three parameters are typically reported when the cervix is checked. The three parameters are dilation, effacement, and station. In addition, other information can be assessed, such as whether the cervix is closer forward of farther back, how soft or stretchy it is, and how the presenting part is arranged in the pelvis (if it is the head, then which way the baby is facing and whether the head is coming down asynclitic).

Typically, active phase for the birthing person will be signaled by an unexpected increase in the intensity of contractions and a tendency to go inward, becoming less aware of the surroundings, and shifting to communication that is quite terse. It is also common for uterine contractions to increase in frequency and for the birthing person to feel each contraction longer. The contractions themselves do not typically become longer, it is just that the person starts to feel them from their onset to their resolution; instead of mostly at their peak. Ideally the birthing person would not be focusing on the frequency and duration of their contractions, because this analysis can actually hinder progress. For the birthing individual and their support person, it is distracting and pointless to focus on contraction pattern, so please do not fixate on timing every contraction.

Transition phase occurs as the last few centimeters of the cervix move out of the baby’s way and the baby descends even lower in the pelvis, possibly starting to exert some pressure on the rectum, which may feel similar to how it feels when you need to defecate. During this phase, the birthing person may second-guess their ability to carry on as the intensity increases even more and the hormonal flux shifts the emotions to doubt. In some way, this is a good place to be, as it is a signpost of being right around the corner from pushing, and pushing brings with it a sense of agency and relief. Observe the image bellow to see how the cervix dilates and the baby descends throughout labor.

Image result for pregnant uterus cervix
Cervical dilation and fetal descent

The transition is the last phase of the first stage of labor and once the person is completely dilated, the second stage begins. Though the second stage is thought of as the pushing stage, the urge to push may not instantly accompany complete dilation. It may take some time for the person to feel the urge to push after their cervix completely dilates. The opposite is also possible, one can have an overwhelming urge to push, but not be completely dilated. An urge to push is less of an urge and more of an involuntary reflex, your body will be doing it on its own. Hence, it is not just a feeling that you have to poop, but its your body seizing up and bearing down, you cannot stop it and it just feels right. If the person reaches the second stage, yet does not feel the urge to push, they can labor down (for hours if need be); essentially, waiting for the baby to descend lower and rotate the head to fit the pelvic outlet, which will typically trigger an overwhelming reflex to bear down when it is time.

Once the baby is born, the third stage begins. It completes with the birth of the placenta. It may seem unsettling not to have timelines included with the description of each stage and each phase, but that is very deliberate. What is considered a reasonable amount of time for each part is not straightforward, a variety of variables should be considered when evaluating labor progress. Presence or absence of specific parameters during labor is a much more meaningful assessment than just the duration of time that had lapsed. For a discussion on safety considerations in regard to time spent in labor, please see the December 2018 entry.

What I hope to communicate in this blog post, is that there is a lot of variability in how individual births look and feel, and that that variation is normal. Even different births experienced by the same person are often very different. Having set expectations and not allowing oneself to be open to the unexpected, will often result in unnecessary anxiety. Being accepting of the path this birth is taking and trusting one’s body, are key to a fulfilling birth.