Labour and delivery Flashcards
What is the definition of labour?
Presence of regular painful uterine contractions becoming progressively stronger and more frequent, accompanied by effacement and progressive dilatation of the cervix and descent of the presenting part
What are Braxton Hicks contractions? When do they usually occur?
uncoordinated contractions in uterus
6-4 weeks before end of gestation
What are the hormonal changes which occur to initiate pregnancy?
- Increase ratio of oestrogens to progesterone
Progesterone inhibits uterine contractility during pregnancy - Both oestrogen and progesterone are secreted in progressively greater quantities throughout pregnancy
- From 7th month oestrogen continues to increase while progesterone stays the same or declines
- Oestrogens increase the degree of uterine contractililty by increasing the number of gap junctions between adjacent smooth muscle
Describe what the ferguson reflex is in relation to pregnancy?
- A positive feedback mechanism involving oxytocin
- Babies head stretches cervix and feedbacks on pituitary
- Pituitary secretes oxytocin into blood and travels to uterine muscle
- Oxytocin stimulates uterine contraction and pushes baby down, stretching the cervix further
- Cycle repeats until baby is born
- Abdominal muscles are activated by neurogenic reflexes to contract and their contraction aids the expulsion of the baby
Describe what happens in the first stage of labour
Latent phase Dilation: 0-4 cm Duration: Often long- especially if its first child
Contractions: 30-60s long. 5-20mins apart
Active phase Established labour
Dilation: 4-10 cm Cervix dilates at of 0.5-1cm/hour Faster in first time mothers. Slower in multi parent
Duration: 12hrs
Contractions: 45-60s. 2-5mins apart
Transition- 60-90s, 2-3mins apart
Describe what happens in the second stage of labour
From Dilation of the cervix to delivery of the baby
Duration: 3hrs for first time mothers 2hrs for multiparents
Contractions: 45-90s long 3-5mins apart
Describe what happens in the third stage of labour
After delivery of the baby to delivery of the placenta and membranes Duration: 30mins
Describe the position of the fetal head during delivery
Left occiput anterior (LOA) is most common
Babies head is slightly off centre in the pelvis with back of the head toward the mothers thigh
When back of baby’s head points directly at the mothers thigh the baby is left occiput transverse
May lead to more pain and slower progression
What happens to the fetal head during delivery?
Bones of the fetal skull are not firmly united which allow moulding
Bones overlap
Head can rotate, flex and extend
How does the pelvis change during birth?
- Widest diameter of pelvic canal changes from transverse diameter at pelvic inlet to AP diameter at pelvic outlet
- longest diameter of the fetal head passes through the widest diameter of the pelvis
- Therefore head must rotate during labour
How is fetal decent measured?
Ischial spin is 0 If presenting part is above ischal spine it is a negative number, -1- -5
If presenting part is below ischeal spine it is a positive number +4cm is the pelvic outlet
What is cervical ripening?
-Increased softening, distensibility, (effacement and dilatation of the cervix)
-Caused by changes to the changes in the biomechanical properties of cervical tissue
Rearrangement and realignment of collagen and an increase in the ground substance
cervical ripening has been compared to an inflammatory reaction, why? What is produced?
Prostaglandins Oestrogens Progesterone and antiprogesterones Relaxin Inflammatory mediators Nitric oxide Apoptosis
What activates abdominal mucles during labour
Neurogenic reflexes- stimulate mucles to contract and aid in expulsion of baby
Describe the fourth stage of labour
From delivery of placenta till postpartum condition stabilises 1-2 hours after delivery Uterus contacts till it returns back to size. Not painful decends 1cm for 10days
