Pregnancy + Birth + Pregnancy Loss Flashcards
+ fetal growth restriction
Give an overview of an average human pregnancy
- last 40 weeks (9 months)
- made up of three trimesters
- 1st: <12 weeks
- 2nd: 12 - 26 weeks
- 3rd: 27 weeks- birth
What are the things that change that the women body needs to change to accommodate for growing a child?
- supplying the baby with enough nutrients
- managing increased waste production: CO2, nitrogen compounds
- change in hormones to support pregnancy and prepare for delivery
- anatomical changes to accommodate the growing fetus ad preparing for labour
- the stress of delivery and potential haemorrhage
- postnatal recovery and breastfeeding require physiological changes
What endocrine changes are seen in pregnancy?
- what do these hormones do?
-
BHCG: dramatic rise in the first days-weeks - released from the corpus luteum then by the placenta
- prevents corpus luteum involution,
- may stimulate the maternal thyroid
-
Progesterone: maintains myometrial quiescence
- inhibits other smooth muscles of the body GI and Urinary Tract
- stimulates the appetite, fat storage and the resp. centre
-
Oestrogen: breast growth, areolar enlargement
- promote uterine blood flow and myometrial growth
- promote cervical softening and expression of myometrial receptors at term
How does the placenta act as an endocrine organ?
- hormones released
- It releases the following hormones
- hCG (human chorionic gonadotrophin) – produced by trophoblast, first detectable 8-9 days, peaks 8-9 weeks.
-
hPL (human placental lactogen) - Similar structure to prolactin and growth hormone.
- a larger placenta produces more hPL.
- Alters maternal carbohydrate and lipid metabolism to provide steady-state of glucose for fetal requirements
-
hPG (human placental gonadotrophin)- induces maternal insulin resistance to regulate fetal growth
- this may become a pathological process seen as GDM
-
CRH (corticotropin-releasing hormone)- implicated in human labour
- acts to increase prostaglandin synthesis
- may also directly stimulate myometrial contractility
- Progesterone
- Oestrogen
What is the role of hPL - human placental lactogen?
- Similar structure to prolactin and growth hormone.
- a larger placenta produces more hPL.
- Alters maternal carbohydrate and lipid metabolism to provide steady-state of glucose for fetal requirements
- antagonises the effect of insulin and promotes lipolysis
- reduces glucose utilization and enhances amino acid transfer across the placenta
What is the role of hPG - human placental gonadotropin?
- released by interstitial trophoblastic cells
- induces maternal insulin resistance to regulate fetal growth
- this may become a pathological process seen as GDM
What is the role of hCG-human chorionic gonadotropin
- maintains corpus luteum secretion of prog & oest, decreases as the placental production of progesterone increases
- beta unit forms the basis of pregnancy testing.
- Alpha unit can mimic LH, FSH, and TSH
- Large quantities are released in molar pregnancy and multiple pregnancies
- High levels cause vomiting (hyperemesis)
What is the role of Progesterone?
- Relaxes smooth muscle – everywhere!
- Maintains uterine quiescence by decreasing uterine electrical activity
- causes Constipation, gastric reflux, supra-pubic dysfunction
- acts as an Immune suppressor ( HLA )
- causes Lobulo-alveolar development in breasts
- Substrate for fetal adrenal corticoid synthesis eg cortisol
What is the role of oestrogen?
- Growth of the uterus, cervical changes
- Development of ductal system of breasts
- Stimulation of prolactin synthesis
What changes are seen in the Haematological System?
- 40% increase in plasma volume - 2.5L to 3.7L (8-10kg fluid weight gain)
-
25% increase in RBC
- these two factors leads to dilutional anaemia (peak at 32 weeks, exaggerated in multiple pregnancies)
- Plasma colloid osmotic pressure falls – shift of fluid into the extracellular space
-
Increase clotting factors –> hypercoagulable state
- Evolutionary balance between thrombosis and haemorrhage
- Increase plasma fibrinogen (increased ESR), platelets, factor VIII & von willebrand factor
What changes are seen in the Cardiovascular system?
- Increased cardiac output
- occurs early on in pregnancy and plateaus at 24-30 weeks of gestation
- Decreased peripheral resistance
- Blood pressure
- proportional to change in CO and PR
- as peripheral resistance is often greater than CO, blood pressure may decrease at various stages of pregnancy

How is peripheral vascular resistance impacted bu pregnancy?
- Peripheral vasodilatation (effect of progesterone)
- Peripheral resistance decreases by 35%
- Combined with increased cardiac output, results in slightly lower BP
- Decreased vascular resistance leads to lower blood pressure
What changes are seen in the Respiratory system in Pregnancy?
- ventilation increased by 40% in first trimester
- tidal volume is increased to meet oxygen demands (deeper breathing rather than faster breathing)
- all done to meet increased O2 consumption
- increased inspiratory and expiratory reserve
- increased vital capacity
- decreased residual volume and total lung volume
- increased abdominal mass
- increased hyperventilation –> decreased PCO2 –> decreased HCO in-order maintain pH
- effects caused by progesterone and prostaglandin
*

What is the clinical impact of the physiological changes on women?
- Splinting of diaphrgm, increased ventilation – sensation of increasing SOB
- Raised HR leads to palpitations
- Lots of cross over with symptoms for PE and known hypercoagulable state… leads to lots of investigations…!
- Excess plasma volume shifts causing oedema – peripheral
- Decreased exercise tolerance
- Low BP causing fainting / dizziness
What are the dermatological and Musculoskeletal impacts of pregnancy?
- Increased lumbar lordosis
- Ligamentous laxity – pelvic girdle pain / pubis dysfunction
- Stretch marks
- Changes in skin pigmentation - Linea Nigra, melasma,
- darkened nipples
- Carpal Tunnel
- Sciatica
- Cramps
What urological changes are seen in pregnancy?
- Kidney increases 1cm in size during normal pregnancy
- increased renal flow by 50%
- increased GFR (BUT tubular reabsorption capacity is unchanged) - decreased glucose reabsorption - glycosuria is common
- Plasma levels of creatinine and urea decrease in pregnancy
- Dilated ureters (progesterone)
- Increased pressure (increased urine frequency)
What changes to Thyroid function are seen in pregnancy?
- Increased serum T3 and T4 levels
- increase in thyroid-binding globulin (caused by oestrogen
- levels of free T3 or T4 remain the same/ slightly fall as most are found in the bound form
How is Labour initiated?
- maternal anterior pituitary is stimulated by factors from the fetal hypothalamus
- fetal hypothalamus-pituitary axis releases cortisol–> plays a role in cervical ripening
- stimulates inhibition of pre-pregnancy hormones
- progesterone
- stimulates an increase in pro-labour hormones
- oxytocin
- the Decidua of the placenta release prostaglandins
- this stimulates cervical ripening and stimulates uterine contractility
- this is through a direct effect and by upregulation of oxytocin
- there is also an inflammatory response that is thought to contribute to cervical ripening
What is the effect of the initiation of labour?
- uterine contractions are stimulated
- there is mechanical stimulation of the uterus and cervix caused by stretching and stretching from the babies head causes the cervix to shorten and dilate?
What are the stages of Labour?
- Latent phase
- 1st stage - 3rd stage of labour
Explain the latent stage of labour
- long exhausting stage of labour, usually a sleepless period for women
- The cervix softens and shortens in response to prostaglandin
- Contractions caused by oxytocin and prostaglandin
- vary in intensity and refularity
What are the stages of cervical effacement?
- measured in percentages
- when the cervix is completely effaced the cervical os starts to dilate

How is Active labour Diagnosed?
- Painful regular contractions
- usually 3 every 10 minutes lasts 50-60seconds from beginning to end
- necessary power in order to give birth
- cervical effacement
- dilatation of the cervix of 4cms or more (digital examination)
- blood-stained mucous discharge, and spontaneous membrane rupture can also form part of the diagnosis
Explain the First stage of Active Labour
- first stage is considered from the time, regular uterine activity associated with progressive effacement and dilatation of the cervix (active labour) until the cervix becomes fully dilated at 10cm
- progression of dilation is usually around 0.5cm/hour
- vaginal examination every 4 hours to check the progress
- can be faster if the mother is multiparous

















