A posterior baby (occiput posterior or OP presentation) occurs when the fetus is head-down but facing the mother’s abdomen instead of the back. This position means the baby’s spine is aligned against the mother’s spine, often called “sunny-side up.” While many babies rotate spontaneously, those that remain posterior can complicate labor significantly. This article details steps to encourage rotation for a smoother birth experience.
The Importance of Fetal Positioning
The ideal fetal position for birth is the occiput anterior (OA), where the baby is head-down, facing the mother’s back, with the chin tucked to the chest. The OA position allows the smallest diameter of the baby’s head to engage with the pelvis, facilitating efficient passage through the birth canal. Most fetuses naturally move into this optimal position by the 36th week of pregnancy.
In contrast, the posterior position often results in the baby’s head being less flexed, meaning a larger diameter attempts to pass through the pelvis. This mechanical disadvantage frequently leads to a protracted first and second stage of labor. Labor with an OP baby can be associated with intense back pain (“back labor”) and a higher risk of intervention.
If the baby remains posterior, there is an increased likelihood of requiring an operative vaginal delivery (forceps or vacuum extraction) or a Cesarean section. The persistent OP position is also associated with an elevated risk of maternal complications like severe perineal tears and postpartum hemorrhage. Encouraging the baby to rotate is important in preparing for a straightforward birth.
Maternal Positions to Encourage Rotation
Specific maternal movements and positions utilize gravity and pelvic asymmetry to create more space and encourage the baby to turn from OP to OA. These techniques should be practiced regularly in the weeks leading up to the due date. The goal is to make the mother’s anterior space less comfortable for the baby’s back, prompting rotation.
A simple technique involves hands-and-knees positioning (knee-chest position). Spending 10 to 15 minutes in this posture multiple times a day helps shift the uterus forward, using gravity to move the baby’s back away from the mother’s spine. Using an exercise or birth ball encourages optimal posture, keeping the hips slightly higher than the knees to create room for rotation.
Forward-leaning inversions are a more intense technique, though they must be done with caution. This involves kneeling and lowering the upper body so the hands or elbows are on the floor, allowing the pelvis to be the highest point for a short duration. This maneuver temporarily releases tension in the pelvic ligaments, giving the baby space to move into a better position.
Pelvic tilts, performed on hands and knees or lying on the back with knees bent, gently mobilize the pelvis and help align the baby for descent and rotation. When sitting, leaning forward over a desk or pillows, rather than leaning back, encourages the baby’s back to move toward the mother’s front. Side-lying can be beneficial when resting, especially on the side toward which the baby’s back is facing.
When to Contact Your Healthcare Provider
While self-correction techniques are valuable, they should be performed in consultation with a healthcare provider before attempting advanced movements like inversions. Seeking professional guidance is important if the baby’s position is still posterior after 37 weeks, as the provider can confirm the position using palpation or ultrasound. Inversion should be avoided if there are medical complications such as high blood pressure or placental issues.
During labor, a provider can offer interventions if the baby remains posterior and labor progress stalls. One intervention is manual rotation, where the doctor or midwife uses their hand internally to gently turn the baby’s head from OP to OA. Studies indicate that a successful manual rotation significantly reduces the rates of operative delivery, including Cesarean sections and instrumental births.
The success rate of manual rotation is high, often exceeding 60%, and it is a less invasive option than proceeding to an operative delivery. It is important to communicate with the birth team about any concerns regarding the baby’s position and the timing of potential interventions.
Labor Management When the Baby Stays Posterior
Despite attempts to encourage rotation, some babies will remain in the posterior position when labor begins. For these labors, the focus shifts to managing the challenges the OP position presents to facilitate a vaginal birth. Frequent changes in maternal position during labor are encouraged, as mobility can still aid in spontaneous rotation.
Walking, lunging, and rocking the pelvis while standing or kneeling are effective ways to open the pelvic outlet and encourage the baby to navigate the birth canal. The use of counter-pressure applied to the lower back during contractions is a common strategy to manage the intense “back labor” pain associated with the OP position. A warm shower, bath, or heat application can also provide relief.
If the baby does not rotate spontaneously or with assistance, the labor may be protracted, requiring close monitoring. If the second stage is prolonged and the baby is not descending, the provider may recommend an assisted vaginal delivery using a vacuum device or forceps to help the baby rotate and exit the pelvis. If labor ceases to progress, or if there is concern for the well-being of the mother or baby, a Cesarean delivery may become necessary.