The 'occiput anterior' position is ideal for birth - it means that the baby is lined up so as to fit through your pelvis as easily as possible. The baby is head down, facing your back, with his back on one side of the front of your tummy. In this position, the baby's head is easily 'flexed', ie his chin tucked onto his chest, so that the smallest part of his head will be applied to the cervix first. The diameter of his head which has to fit through the pelvis is approximately 9.5 cm, and the circumference approximately 27.5cm. The position is usually 'Left Occiput Anterior' or LOA - occasionally the baby may be Right Occiput Anterior or ROA.
The 'occiput posterior' (OP) position is not so good. This means the baby is still head down, but facing your tummy. Mothers of babies in the 'posterior' position are more likely to have long and painful labours as the baby usually has to turn all the way round to facing the back in order to be born. He cannot fully flex his head in this position, and diameter of his head which has to enter the pelvis is approximately 11.5cm, circumference 35.5cm.
If your baby is in the occiput posterior position in late pregnancy, he may not engage (descend into the pelvis) before labour starts. The fact that he doesn't engage means that it's harder for labour to start naturally, so your baby are more likely to be 'late'. Braxton-Hicks contractions before labour starts may be especially painful, with lots of pressure on the bladder, as the baby tries to rotate while it is entering the pelvis. Be aware that if you accept induction on the basis of being postdates, and your baby is in a suboptimal position, you may have a tough haul ahead of you.
No comments:
Post a Comment