Why Is The Fetal Position Important?
The fetal position will determine how easy or difficult your delivery is going to be. If the baby has moved into the right position by the end of the term, she can descend smoothly through your vagina. If she isn’t moving to the right position, then your OB/GYN would decide the course of action.
So, what is the ‘right position’ and the various other positions your baby can get into during labor? MomJunction answers those questions and also tells you about the related issues.
Different Fetal Positions During Pregnancy
Before the due date, your baby will drop down into the pelvis. Here are the different positions your baby can get into when you are preparing for your delivery.
1. Occiput anterior (OA)
This is the ideal position your baby could attain towards delivery. The baby moves into the pelvis with her head-down, facing the mother’s back with chin tucked to the chest. Her head points towards the birthing canal. This is called the longitudinal lie.
Termed the vertex presentation of the fetus, this position is generally attained between 32nd and 36th weeks of gestation (1). The baby will stay in the same position for the rest of your pregnancy. This position is considered ideal for the baby to come out of the birthing canal with head first.
There are two more presentations in the OA position:
i. Face and brow presentation: The baby will remain in the OA position, but her face and not head will be pointing toward the birth canal. This happens when her chin is pointing outward instead of being tucked against the chest. The doctor can identify this position during a vaginal examination, by feeling the bony jaws and the mouth of the baby.
In brow presentation, the baby will be in the OA position but her forehead will be pointing towards the birth canal. During the vaginal examination, the doctor can feel the anterior fontanelle and the orbits of the forehead.
ii. Compound presentation: The baby is positioned anteriorly with one of her arms lying along her head pointing towards the birthing canal. The arms may slide back during the delivering process, but when they don’t, then extra care needs to be taken while taking out the baby safely.
2. Occiput posterior (OP)
The baby moves into the pelvis with her head-down but facing the front/abdomen of the mother. This position is also known as ‘sunny-side up’ or ‘face up’ position. OA and OP are called the cephalic or head-first positions.
Generally, around 10-34% of babies remain in OP position during the first stage of labor and then turn to the optimal (OA) position. But, some remain in this position causing labor complications.
This fetal position can prolong your labor, lead to instrumental interventions, severe perineal tears or a C-section (3).
3. Occiput transverse (OT)
The baby lies sideways in the womb. If she fails to turn to the optimal position at the time of delivery, then a C-section becomes necessary. During the vaginal examination, the doctor can sometimes feel the shoulder, or the arm, elbow or hand prolapsing into the vagina. This position also poses the risk of umbilical cord prolapse, in which the umbilical cord comes out before the baby. About 1% of babies in the transverse position can have a cord prolapse (4), which is a medical emergency and needs an immediate C-section.
In some cases, assisted delivery is carried out by rotating the baby manually or using forceps or vacuum to turn the baby into the ideal position.
4. Breech position
The baby is positioned with her head up and buttocks pointing towards the birthing canal. This occurs in one out of 25 full-term deliveries. It is certainly not an optimal birthing position and prolongs the painful delivery. There are three different variations of breech presentations:
i. Complete breech: The buttocks point towards the birthing canal with the legs folded at the knees and the feet positioned near the buttocks. This position increases the risk of umbilical cord loop in a vaginal delivery. Moreover, the cord could pass through the cervix before the head, causing injuries to the baby.
ii. Frank breech: The buttocks point towards the birth canal with the legs stretching straight up and feet reaching the head. This can also lead to umbilical cord loop, causing injuries to the baby while attempting a vaginal birth.
iii. Footling breech: The baby’s buttocks are downwards, with one of her feet pointing towards the birthing canal. This can cause an umbilical cord prolapse that could even cut off the blood supply and oxygen to the fetus.
5. Umbilical cord presentation
During this, the umbilical cord comes out first through the birthing canal (5). However, there is a difference between umbilical cord presentation and prolapse based on the condition of the uterine membrane.
Whereas a cord presentation happens when the umbilical cord enters the birthing canal before the water breaks, a cord prolapse occurs after the water breaks, which calls for an immediate C-section.
The positions are influenced by the health condition of the mother and the baby.