Opening the Top of the Pelvis
When one level of the pelvis opens, another usually closes or decreases in space to allow for the displacement of the pelvic opening. So, there is no one movement that opens the ENTIRE pelvis. Different types of movement patterns open each pelvic level.
There are three main pelvic levels:
- Inlet (top of pelvis)
- Midpelvis (middle of the pelvis or the actual bony structure)
- Outlet (bottom of the pelvis)
In this blog post, we will be breaking down the top of the pelvis, or the inlet, and the exercises to help baby engage, or enter, into the pelvis.
The Inlet
The inlet is the top portion of the pelvis. Baby begins their descent through the pelvis by engaging, or entering, through the inlet of the pelvis. Engagement is when your baby’s presenting portion (usually their head) has entered into the pelvis. If your baby is still high, they are not yet engaged.
When creating more space in the inlet, you are trying to help your baby engage or enter the pelvis.
In general, the pelvic inlet tends to be wider from side to side and narrow from front to back. Movement patterns like squats or pelvic tilting can create more space at the top of the pelvis.
Why? Because the pelvic inlet opens more with external rotation at the hip and a posterior pelvic tilt or tucking the butt underneath. As a bonus, an anterior pelvic tilt, or arching in the back, changes the pubic bone angle and can make it easier for your baby to rock into the pelvis.
It is important to not fixate on the “best” position for your baby being X, Y, or Z, because the most optimal position for you may be different than mainstream beliefs. Rather, we want to focus on ensuring that you have the ability to create more space in the inlet and that there are no restrictions inhibiting your baby’s ability to move into its optimal position.
Baby's Movement Through the Inlet
At the inlet, your baby engages or enters the pelvis. Your baby may engage during pregnancy, although this is not an indicator that labor will happen sooner or be faster when it does happen. If your baby is engaged before labor even begins, you may not need to do any inlet opening movements at all. You want to create more space in the pelvis based on WHERE your baby is–so if your baby is already past the inlet, you don’t need to do inlet opening movements.
This means that labor positions, or opening certain parts of the pelvis, are not correlated to a specific phase of labor, such as early labor = inlet, active labor = midpelvis. This is not the case; its more about WHERE your baby is, as opposed to what phase of labor you are in.
But some babies do not engage before labor. However this is not an indicator of an issue nor does it predict the onset of labor. If your baby is not yet engaged before labor begins, they may need strong contractions to help them rotate, descend, and stay in their optimal position!
Baby’s first movement into the pelvis includes tucking their head underneath the sacral promontory (junction of the sacrum and the lumbar spine). Typically, they tuck under in an LOA, or left occiput anterior position. Baby then rotates into a LOT, left occiput transverse position, as they enter into the inlet. So, your baby starts at an angle with their head more towards the front, then rotates so the back of their head is aligned with the left hip. Remember, not every baby will engage in a LOT position! For some of us, OP, or occiput posterior, is the optimal position based on our pelvic shapes. But, the key is that baby is trying to first engage by getting under the sacral promontory and then they will fit into the widest diameter of the pelvis. The same movement patterns will open these levels regardless of your pelvic shape.
Baby can be in a number of positions! The occiput or the back of the head is the reference point for their position.
Exercises to Help Baby Engage at the Pelvic Inlet
There are two directions you are trying to create more space in the inlet:
- The side-to-side diameter
- The front-to-back diameter
You can create more space side to side in the pelvis inlet with external rotation of the hip and abduction. You can create more space front to back with a posterior pelvic tilt, which can either be tucking the butt underneath or full hip extension. Additionally, an anterior pelvic tilt can change the pubic bone angle, making it easier for your baby to enter the pelvis. So, in this regard, rocking the pelvis from front to back can make it easier for your baby to enter the pelvis.
Common movements that tend to accomplish these movement patterns, and movements we want to work on during pregnancy to ensure they are accessible to us during labor could include:
- Deep squats with a rounded back; usually best to do with support for the upper body. If any pelvic girdle pain, deep squats may not be optimal for you, but watch the video below to learn some tips that may help you find comfort in a deep squat with pelvic girdle pain.
- Rocking forward and backward; you can do this by standing with the legs closer together if pelvic girdle pain makes wide-legged movements painful, or you can do this on a birth ball.
- Forward lunges or walking upstairs; this is more of an asymmetrical movement pattern but can help bring some external rotation into the leg while walking during the gait cycle.
- Leaning forward at the hips; baby tends to not engage if it is not aligned to the pelvic inlet, and usually baby wants to rotate more forward to align. Leaning forward could help!
Issues at the Pelvic Inlet: Posterior Pelvic Tilt
During pregnancy, you tend to favor more external rotation at the hip and an anterior pelvic tilt (arching in the back). Both of these movements are helpful in creating more space in the pelvic inlet. However, a posterior pelvic tilt is also important in opening the top of the pelvis and helping your baby engage in your pelvis.
A posterior pelvic tilt can be more difficult to find during pregnancy, so incorporating exercises that release tension in the lats, hip flexors, and quads can make it easier to find a rounded back position. You could also incorporate hamstring strengthening exercises to help pull the pelvis into a posterior position! We incorporate these exercises into our prenatal fitness programs.
The top of the pelvis, the inlet, is where baby will first enter the pelvis. When opening the inlet, we are trying to help baby engage into the pelvis. Baby usually enters into the pelvis starting in a LOA then shifts to a LOT position as they engage. Not every pelvis is the widest side to side, and not every baby will engage LOT, so it is important to not fixate on what baby’s position is but rather ensure that there are no restrictions that would inhibit baby’s ability to shift into their optimal position.