Parturition Flashcards
what is the role of the placenta
hormone production
preferential acquisition nutrients and removal of toxins
gas exchange CO2 and O2
why’s there increased fatal oxygen content
higher Hb concentrations (17g/dl)
higher affinity for o2
why is there a shift to the left for fatal haemoglobin over maternal
reduced binding of 2-3 DPG to foetal gamma chains
increased pCO2 and relative acidosis on maternal side and vice very on the foetal
why does 23DPG bind LESS effectively to foetal Hb
fetal Hb contains 2 alpha and 2 gamma chains
23-DPG prefers to bind to B chains and normally would shift curve to the right promoting unloading
when does foetal lung surfactant get produced
from 24 weeks type 2 pneumocystis produce surfactant
what is the structure and role of foetal lung surfactant
mixture of phospholipids PC and PG and apoproteins, SP-A, B, C, D
decreases surface tension at air-liquid interference in the alveoli - allows them to remain open at end expiration
what is the synthesis of foetal lung surfactant stimulated by
by foetal glucocorticoids and thyroid hormones (less so)
what does lack of surfactant lead to in a foetus
neonatal respiratory distress
what therapies are available for lack of foetal surfactant
promote production antenatally - maternal glucocorticoid administration
replace in neonatal period - artificial surfactant - curosurf)
what is the traditional view of the myometrium
single cells interconnect and function as an electrical syncytium
what tissues make up the myometrium
fasciculi
smooth muscle bundles
communicating bridges
what generates electrical potential in the myometrium
any cell can acts as a pacemaker to generate AP
mediated by Ca ions from channels and intracellular stores m- gap junctions involved
what determines propagation along the myometrium
rapid action potential wave (global)
slower intercellular wave (local)
these allow contractions
what happens to contraction interval and resting me bran potential when preparing for labour
decrease in contraction interval and increase in resting membrane potential
what is the most common amount of days it takes before delivery occurs
around 280
what is the diagnosis of labour
regular painful contractions
progressive effacement (thinning of the cervix) and dilation of the cervix
descent of the presenting part
describe the first stage of labour
contractions of uterine muscles force baby towards cervix
cervical opening thins and widens as contractions of lengthwise uterine muscles pull it open
describe the second stage of labour
uterine contractions are aided by mothers involuntary pushes with abdominal muscles
head moves through tilted cervix and birth canal
shoulders and rest of body move through the cervix and brith canal
describe the third stage of labour
placenta separates from uterine wall and is delivered through the vagina
what are the 7 cardinal movements of labour
descent engagement flexion internal rotation extension external rotation expulsion
what are the three physiological differences between foetus and adult
fetal circulation is different
placenta and not lung is the site of gas exchange
these must be reversed at brith
what is the difference between fetal circulation and neonatal circulation
FC - left ventricle to body and placenta, 1) right atrium, foramen ovale left ventricle, 2) RA, RV, lungs or ductus arteriosus (both try to bypass lungs)
NN - LV, body, RV, lungs
what are the 5 points of the APGAR score
appearance pulse grimace activity respiration two points to each
when are the APGAR points measured
1, 5, 10 minutes after birth
what are two examples of abnormal parturition
preterm birth
birth asphyxia
what percentage of cf pregnancies occur in preterm
10 %
what counts as a preterm baby
about 255 days rather than 282 ish
how many babies a year are preterm
60,000
what are the 4 morbidities associated with preterm birth
lung - respiratory distress
brain - intraventricular haemorrhage (cereal palsy)
gut - necrotising enterocolitis (malabsorption)
eye - retinopathy (blindness)
how can you reduce risk of preterm consequences
corticosteroids, ventilation and artificial surfactant
what 4 things can induce preterm labour by triggering cytokines
small uterine capacity
placental abruption
cervical weakness
infection
how can birth asphyxia happen during contraction
compression of the myometrial arteries cessation of flow to placenta lack of gas exchange relative fetal hypoxia anaerobic metabolism gradual lactic acidosis
what are the specific consequences of brith asphyxia
lactic acidemia
tissue
hypoxic-ischemic encephalopathy
cerebral palsy
when is fetal stress more likely to occur
less reserve (low birthweight) long labour placental function impaired
what is a placental abruption
where the placenta breaks aways form the uterus and the space between is filled with blood
what is the management of brith asphyxia
fetal HR monitor
measurement of fetal scalp pH
monitor ST segment changes
if in first stage of labour use C section if in second stage use forceps
