Normal birth Flashcards
What is parturition
Getting the baby foetus from the uterus to the outside world via changes of the cervix and uterus.
Physiological processes in parturition.
Quiescence
Activation
Stimulation
Involution
What is quiesence, what causes it?
Pain less, unsynchronised uterine contractions stimulated by PG2.
What is thought to trigger labour?
FUNCTIONAL withdrawal of PG (decrease PG-A and PG-B receptors fucntion) which decreases E:PG ratio allowing for other sm stimulants such as oxyctocin to induce labour.
Factors determining gestation length.
Parity
Age
Genetics
Ethnicity
How does PG work?
Reduces prostaglandin-F synthesis which induces oxytocin (sm stimulant) release.
Affects Ca2+
Affects Beta-adronergic receptors.
Mifepristone
PG receptor antagonist, used to induce labour or in abortions.
Impact of being human on gestation length
Stress! - Increased in acute phase proteins (CRP, TNF-a) etc. in sustained and high stress environments could reduce gestational length.
What does activation of parturition involve?
Foetal genome
Uterine-stretch - Twins, more stretch, more uterus wants to contract
Upregulation of myometrium via - Gap junctions, Prostaglandins, and oxytocin.
Drugs that inhibit labour for preterm births
Ca2+ blockers inhibit myometrial contractility/excitability
e.g Nifedipine
What is the triad of processes that occur upon labour induction?
- Myometrial contractility
- Cervix ripening
- Membrane rupture association
Three things that up-regulate myometrial activity
- Inc. in gap junctions allowing for more fast and synchronous AP propagation
- Release of oxytocin from post. pit. which induces smooth muscle uterine contractions. Not very good at initiation of labour
- Prostaglandin release which is the most potent inducer of labour. Can be used for abortions as well
Stages of birth
- First stage
- From initiation of labour to full dilation (10cm) - 2nd stage
- Full dilation to birth - 3rd stage
- Birth to placenta delivery
Stages of labour
Latent phase
- Cervical ripening
- Presenting part of baby descends down to pelvis
First stage/active stage
- Real labour commences and full contractions
- Cervical enfacement and dilation until full dilation
- Membranes rupture
Second stage
- Full dilation till delivery of baby
Third stage
- From birth of baby until completion of placental delivery
What is needed after birth
- Ensure continuous breathing as foramen ovale needs to close and theres high pulmonary vascular resistance.
- Thermogenesis- Baby has high vascularised brown fat which maintains body temperature, dry baby off to prevent evaporative heat loss.
- Intermittent nutrition
- Initiates lactation
- Induces uterus contraction to prevent bleeding
- Eye-eye bonding