After reading some of the comments, there sounds to be some confusion about pushing and the mechanism of labour and birth.
Birth is an extremely complex physiological process but very simplistically 4 main things occur:
- Engagement of the baby’s head at the brim of the pelvis
- Descent of the baby through the pelvis
- Rotation of the baby through the pelvis
- Dilatation of the cervix
But this is not a step-by-step process – it’s all happening at the same time, and at different rates. So whilst the cervix is dilating the baby is also rotating and descending.
Spontaneous pushing
The urge to push is initiated by the position of the baby’s head within the pelvis. The urge to push which is generally spontaneous unstoppable pushing, is triggered when the presenting part descends into the vagina and applies pressure to the rectum and pelvic floor. This is sometimes called the ‘Ferguson reflex’. Instinctive pushing does not commence at the start of contractions, and women do not take a deep breath before pushing: women alter their pushing behaviours, and use a mixture of closed glottis and open glottis pushing. The number of pushes per contraction also varies, with women not pushing at all during some contractions. Women also instinctively alter pushes according to their contraction pattern. For example, if contractions are infrequent women tend to use more pushes per contraction, and if contractions are frequent they push less often. This individual and instinctive pattern of pushing helps to oxygenate the baby more effectively than Valsalva (directed) pushing.
directed pushing
Directed pushing is when the midwife directs the woman to push in an attempt shorten the duration of the second stage of labour. It involves taking a deep breath as a contraction begins; holding the breath by closing the glottis; bearing down forcefully for eight to ten seconds (into the bottom); quickly releasing the breath; taking another deep breath and repeating this sequence until the contraction has ended. It’s usually done if the woman has an epidural, there’s a delay in the second stage or the baby is distressed, they will also be instructed to push if it’s an instrumental birth (forceps/ventouse)
Crowning
This is where the head is emerging and is visible. Some midwives will encourage women not to push as the baby’s head is crowning (when the stinging and burning sensation happens) The rationale of this is to minimise the chance of perineal trauma/tears by slowing down the birth of the baby’s head. A slow birth of the head reduces the chance of tearing as it allows the perineal tissues to gently stretch over time. Some midwives will also use this technique whilst placing one of their hands on the baby’s head whilst using the other hand to guard your perineum in an attempt to slow down the birth of the head, and to reduce the risk of perineal tears/trauma.
However, the intense sensations experienced during crowning usually result in the woman ‘holding back’ themselves so there’s no need for the midwife to use directed pushing on hands on techniques as the uterus continues to push the baby out slowly and gently. In addition, women will often hold their baby’s head and/or their vulva during crowning. Some women will bring their legs closer together, not only slowing the birth but also providing more ‘give’ in the perineal tissues.
So, in a nutshell there’s no need for the midwife to direct you to push or hold back pushing when the baby is crowning, unless the baby needs to be born quickly due to being distressed or if you’ve had an epidural. You can help protect your own perineum by placing your hands gently to feel for baby’s head and you’ll instinctively let the muscles gently push the baby out. You do however have to do some pushing to get the baby to crowning stage as the baby needs to decent through the pelvis and through the birth canal (cervix and vagina)
Here are some good articles to understand the mechanism of pushing and perineal tears, and why midwives/obstetricians use certain techniques to try and prevent tearing.
www.google.co.uk/amp/s/midwifethinking.com/2015/09/09/supporting-womens-instinctive-pushing-behaviour-during-birth/amp/
midwifethinking.com/?s=Ferguson+reflex&submit=Search