REPRO childbirth intro session 2023 (1).pptx

Reproduction Week 8 Childbirth Dr Sue Smith Structure of the week Intro Session - initiation of parturition GLS Mechanisms of labour Maternal postpartum changeslactation Neonatal adaptations Synthesis session Review of labour and delivery Intro session EDD’s Pre and post term delivery Ch...

Reproduction Week 8 Childbirth Dr Sue Smith Structure of the week Intro Session - initiation of parturition GLS Mechanisms of labour Maternal postpartum changeslactation Neonatal adaptations Synthesis session Review of labour and delivery Intro session EDD’s Pre and post term delivery Changes in the fetus for extra-uterine life Hormonal cascade that initiates and maintains labour Changes in the myometrium and cervix Clinical implications – drugs to induce or delay labour Stages of labour Apgar scores EDD- estimated date of delivery LMP plus 280 days (9 months and 7 days or 40 weeks) from first day of last menstrual period Ultrasound dating. Measures BPD (biparietal diameter) &/or femur length. +/- 3 days at 7 weeks +/- 7-10 days at 18 weeks +/- 3 weeks at term EDD – why does the due date matter? The due date guides you and your provider in gestational ageappropriate prenatal care, testing, and ultimately your baby's birth Gives family time to prepare Antenatal screening eg for Downs syndrome (47 XO trisomy), klinefelters (47 XXY trisomy) etc and if the baby is worth keeping ie helping. Why does the due date matter? Booking an elective caesarian Deciding when to induce labour in a woman with mildly raised BP or who is past her EDD Working out whether the baby is growing well Interpreting antenatal screening eg for Downs’ syndrome Some clinical definitions Preterm : less than 37 completed weeks Term : 37 to 42 completed weeks (37-38 early term) Post term: more than 42 completed weeks Preterm delivery occurs in about 12% births, but causes >70% neonatal morbidity and mortality-> main concern, what sets off pre term labor? Test your memory (more than one may be correct) An accurate EDD is important for A) setting the date for an elective caesarian section B) diagnosing antepartum haemorrhage C) knowing when labour will start D) diagnosing preterm labour (based on 37 week mark) Foetal maturation Survival of neonate dependent on functional maturation of systems essential for extrauterine life ◦ Organs that interface with environment – lungs, intestinal tract, immune system Organs that maintain homeostasis hypothalamic-pituitary axis, kidneys, liver, pancreas Glucocorticoids (cortisol) promote functional maturation of key foetal organ systems: ◦ Eg ◦ Surfactant production in lungs ◦ Deposition of glycogen in liver ◦ NaK ATP’ase activity in cortical tubules enabling Na reabsorption Example : Corticosteroids & Lung Maturation  Surfactant enables alveoli in the lungs to remain expanded when foetus is born & takes its first breath  Rising foetal corticosteroids stimulate synthesis of surfactant in human lung from about 18-20 weeks  Surfactant is produced by cells lining the alveoli  Failure to secrete sufficient surfactant seriously interferes with lung expansion What initiates parturition? Labour Day (baby knows best) Initiation of labour Glucocorticoids have a role here too– but exogenous steroids do NOT initiate labour in humans (unlike sheep). http://www.waterforducc.com/wordpress/wp-content/gallery/2012-05-01_sheep/ Role of glucocorticoids CRH (corticotropin releasing hormone) from placenta stimulates foetal HPA and adrenal to produce large amounts cortisol towards end of pregnancy. Positive feedback loop between foetal cortisol and CRH CRH / Cortisol stimulates placenta to produce Prostaglandins (PG) CRH stimulates Oestrogen production CRH Adapted from Marieb EN, Hoehn K, Human Anatomy and Physiology 2016 10 th ed Chap 28 p1116 What does oestrogen do? – prepares the uterus 1. an increase in number of oxytocin and PG receptors in uterine muscle-> 2. changes in uterine muscle (gap junctions, ion channels) –ie electrical connections between myometrial cells 3. Stimulates both oxytocin and PG production by foetus/placenta (probably) 4. (and acts to soften the cervix -more on this later) CRH & PG *****Induces gap junctions in myometrium Marieb EN, Hoehn K, Human Anatomy and Physiology 2010 8 th ed Chap 28 p1091 Myometrial changes Big enough to held a baby as The baby grows. Myometrial ce And multiply and come in longe Cells doing their own thing then Cells multiply and hypertroph y  http://www.pregnancy-week-by-week.net/pregnancy-week-24.php What about progesterone? During pregnancy progesterone relaxes the uterus: involved in maintenance of pregnancy. Functional withdrawal of progesterone allows myometrial contractility (Probably: At the end of pregnancy uterine progesterone receptors decrease and oestrogen receptors increase. And/or release of a progesterone binding protein) Proges Proges Oestro Couple Around Has a Test your memory (more than one may be correct) At the end of pregnancy, Corticotropin releasing hormone (CRH) and/or cortisol stimulate release of A) placental progesterone B) placental estrogen yep C) prostaglandins yep D) foetal lung surfactant yep CRH ACTH Adapted from Marieb EN, Hoehn K, Human Anatomy and Physiology 2016 10 th ed Chap 28 p1116 What do PG and Oxytocin do? – cause Uterine Contractions Just need to know p Prostaglandins PG (PGE2 & PGF2 ) from myometrium/placenta/decidua  in response to CRH/cortisol, oestrogen , oxytocin, and contractions. Very powerful at causing contractions Soften the cervix Oxytocin from placenta, in response to oestrogen. Oxytocin from maternal pituitary in response to stress/stretching/pain stimuli Oxytocin stimulates contractions to increase in strength and frequency Oxytocin stimulates PG production Ripening the Cervix Process begins several days before parturition Cervix Needs t Through This is a Progeste is mostly connective tissue (85- 90%) & smooth muscle (10-15%) Cascade of events “ripen” the cervix driven by estrogen, prostaglandins Inflammatory cytokines (IL-2 & IL-8) produced by the placenta & cervical fibrocytes also play a role If it isn’t Not be i Dilatation and effacement http://giftofmotherhood.com/stormontvail/files/assets/seo/page36_images/0003.jpg Relaxin Probably causes cervical softening & relaxation of maternal pubic symphysis (and other pelvic joints) in late pregnancy When all happening together Cervix softens and increases in elasticity Increasin Of proge Concurrently myometrium gains capacity to contract forcibly and rhythmically. Maintenance of contractions: increased levels of and increased responsiveness to PG’s and oxytocin. Overall Summary Hormonal cascade leading to birth Contribution by foetoplacental unit. Role of placental CRH and foetal cortisol in both foetal maturation and initiating labour. Cause increase in estrogen and prostaglandin production “Functional withdrawal” of progesterone Estrogen stimulates production of PG & oxytocin and their receptors as well as changes in myometrium Placental oxytocin stimulates contractions and also causes more PG release. Maternal pituitary also > oxytocin in response to stress PG’s involved in contractions, cervical softening Positive feedback cycle > Maintenance of labour – oxytocin and PG’s Test your memory (more than one may be correct) Prostaglandins cause A) uterine contractions B) placental estrogen productionwhat estrogen does. C) softening of the cervix D) antagonise progesterone Preterm birth Causes before 37 completed weeks of pregnancy mostly unknown: Include uterine over-distension (eg twins) Infections Antepartum haemorrhage Previous preterm delivery Smoking Maternal diabetes/hypertension affecting placenta Methods to delay or induce labour Delay: [antiprostaglandins,] Bagonists (eg salbutamol, to relax smooth muscle), or Ca Channel inhibitors (relax smooth muscle) Induce: oxytocin, prostaglandins, break amniotic membrane. Test your memory (more than one may be correct) Methods of inducing labour include using A) corticosteroids-> does not work clinically B) antiprostaglandins-> does the opposite to prostaglandins C) prostaglandins-> softens cervix for labour D) oxytocin-> contractile process E) estrogen does not -> too slow perhaps??? At the start of labour Full term Vertex presentation – high yield - name for a baby which is head down, part that comes first reasons for that is smallest diameter to try and get head through the pelvis. So the delivery plan is good. Healthy baby Healthy prepared mother Delivery plans in place Physical factors for a normal labour Passages large enough to fit baby Nothing in the way Baby small enough to fit through ◦ Size – average newborn weight? ◦ Position – head first, head flexed Efficient Normal co-ordinated contractions pelvis with nothing in the way, baby cannot be too big, position which effects the birth delivery, if the head is extended or not in fetal position it is head. Signs of onset of labour Regular painful contractions Progressive cervical effacement Progressive cervical dilatation-> cervix becomes progressively more dilated. Some contractions can be sporadic due to progesterone wearing off, but does not mean they are going into labour Stages of labour Pre- labour: cervix softens and becomes stretchable Stage 1 – start of regular contractions to fully dilated (=10cm). Could be latent or active Stage 2 – full dilatation until delivery of baby-> cervix fully dilatede and out of the way-> baby moving down the pelvis to be delivered, cannot push before that because cervix is not dilated Stage 3 – delivery of baby until delivery of the placenta -> cevix attaches to uterine wall-> lots of blood vessels-> shears the placenta onto the wall, and sheds the blood vessels, make sure the know uterus contracts tightly to stop blood vessels from passing through the myoemtrium and a shot of oxytocin stops this. APGAR scores Widely used assessment of status of newborn Score at 1 min and 5 min Helps assess how well baby is adapting, and response to any resuscitation Initial score does not predict outcomes of individual baby 7-10 doing well, no resuscitation needed 4-6 may require assistance with breathing 0-3 more likely to need resuscitation Blue baby is not good /scotdir.com/wp-content/uploads/2015/9/newborn-health-what-is-apgar-score_1. Good, higher the HR NEXT EPISODE – in the GLS