17 Labour and Delivery Flashcards
Before which week of gestation is parturition know as pre-term/premature labour?
Before 37 weeks gestation
(due date= 38 weeks gestational period, 40 weeks embryonic period)
Outline what occurs in the 1st, 2nd and 3rd stages of labour.
At around which week during gestation does the uterus become palpable?
12 weeks
What does the ‘lie’ of the fetus describe and what does the ‘presentation’ of the fetus describe?
Lie= relationship of fetus to long axis of uterus (normal=longitudinal)
Presentation= which part of fetus adjacent to pelvic inlet
(if baby= longitudinal then can be head or breech)
What are the boundaries that form the pelvic inlet? What is the normal diameter of the inlet?
11cm
What happens to the pelvic ligaments in preparation for birth?
Softening of ligaments- allows some expansion to occur
What happens to the cervix during the 1st stage of labour (creation of birth canal)
Cervical softening (‘ripening’)
Contractions of smooth myometrium cause:
Cervix thins- effacement
Cervix dilates
Fetal membranes rupture, aminotic fluid released
What happens to the myometrium during pregnancy?
Gets thicker:
- Smooth muscle cells increase in size
- Glycogen deposition
How does the myometrium contract during pregnancy? (before labour)
What 2 hormones bring about the increase in frequency and force of contractions of the myometrium and how do they work?
Onset of labour=
increased prostaglandin synthesis and release
+
increased sensivity to oxytocin
State the crucial property that uterine smooth muscle possesses which allows for birth to occur. How does it work?
Brachystasis
Muscle fibres shorten at each contraction
DO NOT relax fully
Uterus (fundal region esp) shortens progressively
Descent of presenting part of fetus into birth canal
What can be given to induce labour medically?
Prostaglandins
Outline how the ferguson reflex increases contractions:
As labour progresses, explain why there might be a slight dip in the fetal heart rate. What happens if this lower heart rate goes on for too long?
Increased forceful uterine contractions
Reduced blood supply to placenta temporarily
Fetus= distressed if ‘dips’ too long
At what point does the first stage of labour end?
Usually when cervix= dilated 10 cm
How long does the second stage of labour (giving birth) normally last? (think primigravida and multiparous)
Multiparous= 1 hr
Primigravida= 2 hrs
Outline the second stage of labour: (birth iteself)
When does the second stage of labour end?
Second stage: Ends with delivery of fetus
What happens during the 3rd stage of labour?
- Powerful uterine contraction
- placenta pushes into lower uterine segment/upper vagina
- Compresses blood vessels and reduces bleeding
- Placenta and membranes expelled (in about 10 mins)
What drug can be given to enhance the contration of the uterus in the 3rd stage of labour and therefore reduce bleeding?
Oxytocic drug
Name some congenital conditions that arise as a result of failure of the fetal circulatory shunts to close (think CVS embryology).
- Patent foramen ovale (atrial septal defect)
- Patent ductus arteriosus
- Patent ductus venosus
What changes occur in the baby once its born that cause the fetal circulatory shunts to close?
What score system is used to assess the wellbeing of the neonate following delivery?
APGAR score
after delivery and then 5 mins later
Score= 1-10
Higher score- healthier baby
The clinical elements of labour are made up of: the powers, the passage and the passenger. What is ‘the powers’?
- Contraction of myometrium
- Contraction and retraction of multidirectional smooth muscle fibres
The clinical elements of labour are made up of: the powers, the passage and the passenger. What is ‘the passage’’?
- Bony pelvis
-
pelvic outlet= narrowest mediolaterally
- fetus: flexes, extends and rotates to exit
-
pelvic outlet= narrowest mediolaterally
- Soft tissues
Failure of the progress of labour can be caused by abnormalities with either the power, the passage, or the passenger. Give an example of an abnormlity for each element:
- Power
- insufficient uterine contractions
- Passage
- abnormal bony pelvis
- rigid perineum
- Passenger
- macrosomia
- fetal presentation
What measurements does a partogram take and what is it used for?
Measurements:
cervical dilation, fetal heart rate, duration of labour and vital signs
Why?:
intended to provide an accurate record of the progress in labour, so that any delay or deviation from normal may be detected quickly and treated accordingly
What are the causes of post partum haemorrhage? (4Ts)
- Tone
- Thrombin- clotting disorder
- Trauma- tears
- Tissue- placenta
