Pregnancy and birth Flashcards
Factors that initiate birth
Hormonal changes
- Fetal and maternal
Mechanical changes
Decidua release of prostaglandins
Hormonal initiation of labour [5]
Fetal hypothalamus triggers activation of maternal hormonal release
Fetal cortisol triggers placental hormone release
Rise in oestrogen, drop in progesterone
Oxytocin from posterior pituitary + prostaglandins from decidua= uterine contractions
Mechanical stimulation during labour
Overstretching and pressure causes baby to mechanically stimulate the uterus and cervix
Latent phase labour
Length: hours to days
Cervical effacement
- Thinning of the cervix
Contractions of varying intensities
Cervical effacement
The thinning of the cervix that initiates during latent labour.
The cervix starts at a bottle neck shape, 4cm long, then thins and widens
- When the cervix is not palpable, it is fully dilated.
Second stage of labour
Delivery of the baby after full dilatation (10 cm)
Anteroposterior diameter of pelvic brim
12cm
During labour the baby’s head transverses the oval pelvic brim
Diameters of the pelvic outlet
Outlet is diamond shape
Anteroposterior diameter
- 12.5cm wide
- Space available for the baby;s delivery
- Coccyx moves backwards during birth
Oblique diameter
Transverse diameter
- Space between the ischial spines.
Occiptofrontal diameter
- Description
- Length
- Function
The diameter between the frontal and occipital bone
- 11cm
Delivery via this diameter is more difficult
- Baby’s head is extended
- Anterior fontanelle is visible.
Suboccipitobregmatic diameter - Description - Length - Function
The length between the anterior (bregma) fontanelle and occipital bone
- Line below posterior fontanelle.
- 5 cm
- Most ideal fetal position for childbirth
- Head is flexed, only posterior fontanelle visible.
Anterior fontanelle closes at …
18 months
Posterior fontanelle closes at …
6-8 weeks
Supraocciptomenal diameter
- Description
- Length
- Importance
The length between the mental bone (chin) and occipital bone
- Line above posterior fontanelle
13.5cm
Least ideal position for the baby to be born in (brow position)
- Most likely convert to C-section
- Anterior fontanelle visible
Submentobregmatic diameter
- Description
- Length
- Importance
The length between the mental bone and bregma fontanelle
9.5cm
Baby is born in ‘face’ position
OT position
Occipital-transverse positon
When the baby’s head is facing the mother’s thigh (occipitofrontal)
Mechanism of birth
- Head descends to pelvic brim in OT position.
- Flexion of the head showing suboccipitobregmatic diameter
- Head descends further and reaches pelvic floor.
- Head rotates to OA position and is delivered by extension.
- Head comes in line with the shoulders (restitutes)
- Shoulders rotate to AP diameter of pelvis - Anterior shoulder delivered by downwards lateral flexion of baby’s head
- Posterior shoulder delivered by upwards lateral flexion.
OA position
Occipital-Anterior position
Baby’s face is facing towards the back of the mother
Third stage of labour
Delivery and inspection of the placenta
Blood loss
- 300-500ml
Things inspected after placental delivery
Position of umbilical cord
- Marginal?
- Velamentous?
- 2 arteries and a vein?
Complete umbilical cord
- Left over in uterus can cause inflammation
Checking the membranes
- Amniotic
- Chorionic
Placental delivery
Can either be physiological
- After breastfeeding
- Release of oxytocin stimulates uterine contraction= expulsion of placenta
Active management
- Oxytocin given i.m
- Decreases placental bleed and post-haemorrhage
Intermittent auscultation
Done using a pinard/ sonicaid
First stage of labour
- Fetal heart beat listened 15 mins before and after contraction
Second stage
- Every 5 mins
Any abnormality= CTG use
CTG
Cardiotocograph
- Monitors uterine contractions corresponding to fetal heart rate
Abdominal ultrasound–> cardiac movements (more common)
OR
Clip attached to fetal scalp (FSE)
- Detects R-R wave in fetus
Very sensitive but not specific
Fetal blood sampling
Used as a more specific measure after CTG
- Checks findings found in CTG
Fetal scap stabbed and blood sample collected with capillary pipette
- pH and base excess calculated
Contraindications of FBS
Infections
- HIV, Hep B
Fetal bleeding disorder
- Haemophilia
Prematurity <32 weeks.
