Physiology of pregnancy and parturition Flashcards
What are the maternal adaptations to pregnancy?
- Progesterone is high
- Higher prolactin
- uterus increases in size
- Plasma volume increases, CO increases, uterine blood flow increases
- varicose veins
- increased clotting factors
- ventilation increases
- dyspepsia
- constipation as progesterone inhibits SM contractions
- linea nigra
- lumbar lordosis
- bladder freq increases due to pressure from baby’s head
What do the endocrine changes in pregnancy and labour acheive?
- Oestrogen regulates progesterone and prepares uterus for baby
- Progesterone prevents uterine contractions and builds up endometrium for the placenta
- prolactin produces milk
- oxytocin produces contraction in labour
- Prostoglandins initiate labour
What is myometrial quiescence?
where the smooth muscle of the uterine wall does not contract during pregnancy due to progesterone action
What can you use to increase uterine contractions?
Can use ergometrine (alpha adrenergic agonist) and syntocinon (oxytocin agonist)
What is rhesus disease and how can you prevent it?
Where foetal cells are rhesus positive and maternal negative causing lysis of foetal RBC
Prevent with anti-D which destroy anti-rhesus positive IgG
What is presentation?
Part of the foetus that first emerges through the birht canal - ideally is the flexed part of the head (vertex cephalic)
What is the lie?
the relationship between the long axis of the foetus and the long axis of the uterus
longitudinal ideal
What is the station?
relationship between the lowest point of the presenting part and the ischial spines
What is effacement?
when cervix softens, starts in the fundus where the fibres will shorten, it builds in amplitude as labour progresses. Cervix must soften to 10cm wide.
What is defined as a normal birth?
no induction of labour, epidural, general anaesthesia, forceps, ventouse delivery, c-section or episiotomy
What are the different phases of labour?
latent (0-3cm)–> active (3-7cm)–> transition (7-10cm) –> second stage (pushing stage) —> afterbirth
What happens in the latent phase of labour?
Irregular contractions
0-3cm dilation
Show mucoid plug - can be blood and mucus “bloody show” or amniotic sac ruptures “water breaking”
Can be between 6 hours and 2-3 days
Cervix is effacing and thinning
Stay at home, take paracetamol, position and keep hydrated
What happens in the active phase of labour?
3-7cm dilation
Regular and frequent contractions caused by oxytocin
What are the 3 P’s of the latent phase of labour?
Powers (forceful uterine contractions), passage (route through pelvis- baby’s head is unfused to help with this), passenger (foetus)
What happens in the transition phase of labour?
7-10cm dilation
Strong and regular contractions
rupture of membrane if has not occured already AKA water breaks
Irritable, anxious and distressed
Feel pressure- need to empty bowel around this time
Contractions slow/stop
What can be done to speed up the start of labour?
artificial rupture of membrane- sweep the membrane manually to break waters
give oxytocin eg syntocinon
What is the second stage of labour?
Full dilation
External signs- can see head
Spont bearing down is ideal position
Take around two hours normally for first time
Discourage supine position
We want baby to be longitudinal ie head in line with pelvis, not transverse or oblique which can impede labour
What is skin to skin?
When baby is put in direct contact with mother after birth without blanket or top in way to keep baby warm
What happens in afterbirth?
Deliver placenta
Blood loss
oxytocic
Uterus contracts to >24-week size
Separates from the uterus through the decidua basalis- attached at uterine wall
Delay clamping placenta as decreases baby’s chance of anaemia
What are the cardinal movements of labour? Name them.
the movements the baby must do to be born
descent –> engagement –> flexion –> internal rotation –> crowning –> extension —> restitution –> expulsion (DEFICERE)
What happens in descent?
downward movement of foetus to pelvic inlet. Pelvic inlet is at about station –5, ischial spine is station 0
What is engagement?
where foetus reaches ischial spine (station 0)
widest part of the presenting part has passed through the brim of the pelvis ie the head is mobile above pubis symphysis
What happens in flexion?
chin against chest, resistance from pelvic floor
What happens in internal rotation?
shoulder rotate internally 45 degrees so that the widest part of shoulders are inline with widest part of pelvis
What happens during crowning?
head at pubic symphysis, around station 4, the perineum thins, this is where tears are most likely to happen
What happens during extension?
head changes from flexion to extension and emerges from vagina- +5 station
What happens during restitution?
head externally rotates so that the shoulders can pass through the pelvic outlet and under symphysis pubis
What happens during expulsion?
anterior shoulder slips under symphysis pubis then other shoulder and rest of body follows
What non pharmacological interventions are there for pain in labour?
Position- forward sitting and anterior helps keep baby lateral- less pain
If feel better psychologically and calmer there will be less adrenaline –> oxytocin works better
Breathe out with contraction- less pain and more oxygen to baby
Positive reinforcement eg one more contraction until you see the baby
Hydrotherapy
Birth environment
Complementary- massage, acupuncture, reflexology, aromotherapy, reflexology
TENS- electric shock
What medications are used for pain relief in labour?
Entonox (mix of NO and oxygen) aka gas and air/ laughing gas
Diamorphine/ pethidine
Epidural- most effective
What are the side effects of entonox?
nausea and vomiting
What are the SE of diamorphine?
foetal- resp depression, less breastfeeding seeking behaviour
maternal- euphoria or dysphoria, N+V, labour longer
What are the SE of an epidural?
maternal- increase labour length, oxytocin, malposition, loss mobility and bladder control, pyrexia
foetal- tachycardia from maternal temp, diminish breast feeding behaviours
What does gravidas mean?
Gravidas= number of times been pregnant, multiple pregnancies count as 1
What does parity mean?
Parity=number of babies had after 24 weeks —-> usually written as G?P? –1 indicates a loss after 24 weeks
What is the difference between nulliparous and multiparous?
Nulliparous = no live babies delivered Multiparous = has delivered potentially live babies
WHat is IUFD vs stillbirth vs neonate death?
- IUFD: Babies with no sign of life in utero (before 24 weeks death)
- Stillbirth: Baby delivered with no signs of life, known to have died after 24 completed weeks of pregnancy
- Neonatal death: The death of a baby within the first 28 days of life.
What should be asked about in HPC for an obstetric hx?
Nulli/ multiparous
EDD (estimate date delivery)- in 40 weeks, dates by 1st trimester U/S
Previous pregnancies- year, gestation by week!!, outcome, mode of delivery, complications
- TOP (terminations)
- miscarriages – for above two at what stage, what happened and for TOP how
- Ectopics
- Any stillbirths, neonate death, IUFD
- delivery mode NVD (normal), ventouse, forceps, LSCS –elective or emergency
- birth weight –> SFD (small for date), LFD (large for date)
- sex baby
- hx labour – show (mucus or blood), contractions (onset, frequency, length and regularity–> 3 in 10 indicates 3 contractions in 10 minutes), SROM (waters broken- colour!!! If yellow/green can indicate infection or foetal distress)
- ——> can look at partogram for obs
Early pregnancy scans
FULL gynae hx
What should you ask about in PMHx for obstetrics?
PMH chronic consition specifically DM, heart disease, htn, psych, epilpesy, abdo operations
Mental health
Risk factors for VTE/pre-eclampsia
WHat should you ask about in Fhx for obstetrics?
Fhx DM, heart disease, genetic abnormalities, thrombophilia
