This can be if:
The baby's head is not flexed. If the baby's head is slightly deflexed, (that is the baby's chin is not resting on their chest, looking down, therefore looking forward or slightly up), the crown of the baby's head does not 'lead the way'. The crown of the baby's head needs to sit snugly onto the cervix (like an egg in an eggcup), to be an 'efficient dilator'. If the head is deflexed, the width of the baby's head is effectively larger, making their negotiation of the pelvis more difficult and slowing the progress of the woman's labour.
Strong, uterine contractions can encourage the baby to 'tuck their head in'. Augmenting the labour (with an oxytocin drip or natural therapies) may help with this, however, breaking the waters may 'wedge' the baby's head down into the woman's pelvis in the awkward position. If the waters are already broken, and the cervix is (or is nearly) fully dilated, it may be an option for the caregiver to place some pressure on the front of the baby's head during a contraction, to help the baby tuck their head in. This is done by the caregiver performing a vaginal examination.
Image 4-04 shows the baby's head deflexed, with the crown of the head not sitting snugly in the pelvis.
Image 4-05 shows the baby's head flexed, with the crown of the head sitting snugly in the pelvis (and therefore on the cervix).
The baby is in a posterior position. Sometimes the baby being in a posterior position, can make the progress of a woman's labour slower than average. A posterior position is where the baby's backbone, is on their mother's backbone (or the baby is facing towards the mother's front). The baby generally needs to rotate towards the front of their mother about 45- 90
o more than if it were in an anterior position. This can slow the progress of the labour. In some cases, the baby's head remains high (unengaged) until the contractions guide it down into the pelvis, and around a little.