Pregnancy Flashcards
From when can maternal blood reach placenta?
After 10-12 weeks
How many vessels are there in the umbilical cord?
1 vein carrying blood and oxygen to the baby
2 arteries carrying waste products to the placenta
What prevents maternal blood flow to the placenta?
Endovascular trophoblast
In 2nd trimester, this plug had disappeared and blood can flow freely
What is histiotrophic nutrition?
Nutrition provided to the baby from the endometrium and uterine gland
What is haemotrophic nutrition?
Nutrition provided to the baby from the maternal blood flow
What is the syncytiotrophoblast?
is the epithelial covering of the highly vascular embryonic placental villi, which invades the wall of the uterus to establish nutrient circulation between the embryo and the mother
Describe the blood transport from mother to baby (4 vessels)
Maternal uterine artery
Fetal umbilical vein
Fetal umbilical artery
Maternal uterine vein
How is fetal HCO3- excreted?
HCO3- is converted into carbonic anhydrase into CO2, which follows concentration gradient and is expired by mother
When is the gut fully developed?
Week 19
What is macrosomia?
Overweight at birth
What are the complications related to macrosomia?
Causes labour difficulties
Associated with increased obesity
Increased risk of stillbirth
Often C section, as brachial plexus can get damaged
How much fluid do fetal kidneys produce?
500-700mL, becomes part of amniotic fluid
What is the fetal heart rate determined by?
Catecholamines and chemoreceptors
Parasympathetic tone
What is the ductus venosus?
shunts a portion of umbilical vein blood flow directly to the inferior vena cava
What is the foramen ovale?
is a normal opening between the upper two chambers (the right atrium and left atrium) of an unborn baby’s heart. The foramen ovale usually closes 6 months to a year after the baby’s birth.
What is the ductus arteriolus?
is a normal blood vessel that connects two major arteries — the aorta and the pulmonary artery — that carry blood away from the heart
How does the foramen ovale close?
Cord occlusion changes arterial pressure and presses the foramen ovale shut
What are the two types of alveolar cells?
Type I allow for gas exchange
Type II produce surfactant (larger cells, stabilise lungs, decrease surface tension)
What is the relationship between surfactant and prematurity
Less production of surfactant, leading to difficulty breathing
what is the treatment for inadequate surfactant?
Exogenous surfactant
Give mother steroids so lungs develop faster
What are the two parts of a blastocyst?
- Trophoblast (outer)
2. Embrryoblast (inner)
What is the acrosome reaction?
Zona protein 3 (ZP3) on the egg binds with the sperm
This initiates the acrosome reaction, exposing hyaluronidase and acrosin in the acrosome to the egg.
This activates the oocyte, causing cortical granules to be released , preventing polyspermic penetration.
Meiosis resumes
What is linea nigra?
Often referred to as a pregnancy line, is a linear hyperpigmentation that commonly appears on the abdomen
Often seen in first trimester
What causes linea nigra?
MSH production by the placenta
If there are concerns about the fetus’ growth, what investigations do you do?
Amniotic fluid index (normal range 5-25 cm) and uterine artery doppler
When is the first ultrasound offered to all pregnant women?
12 weeks
When is the second ultrasound done in pregnancy?
18-20 weeks
What is measured during the second ultrasound in pregnancy?
Here the fetus is checked for abnormalities and there is an assessment of fetal growth, it includes four measurements: Head circumference Bi-parietal diameter Abdominal circumference Femur length
During what developmental phase is the embryo at greatest risk of morphological abnormalities?
Embryonic phase
During what developmental phase is the embryo at greatest risk of functional abnormalities?
Fetal phase
How do HR, CO, BP, aldosterone, angiotensin II and renin change during pregnancy?
Heart rate = increases Cardiac output = increases Blood pressure = decreases Aldosterone = increases Angiotensin II = increases Renin = increases
When are chromosomal screening tests offered?
Who - all women
When - first trimester scan
How - USS fetal nuchael translucency and blood test (HCG, PAAP-A)
If positive - counselling, termination
What is circulating testosterone bound to?
Sex hormone binding globulin
How do clotting factors and plasma fibrinogen levels change in pregnancy?
Clotting factors VII, VIII, X = increases
Plasma fibrinogen = increases
Fibrinolytic activity = decreases
What is the result of maternal rubella infection during the first 20 weeks of pregnancy?
Eyes - Congenital cataracts, pigmentary retinopathy
Heart - Patent ductus arteriosus
Neurological - Microcephaly, developmental delay
ENT - Hearing impairment
What hormones do FSH and LH stimulate?
Inhibin and oestrogen
What do Inhibin and oestrogen do in females?
Oestrogen regulates the menstrual cycle whereas inhibin inhibits activin.
Increasing oestrogen and inhibin have a inhibitory effect on the pituitary and hypothalamus, leading to decreased production of LH, FSH and GnRH.
What does LH do in men?
LH is released from the anterior pituitary, stimulating Leydig cells to produce testosterone.
Who do testosterone and FSH do?
Testosterone and FSH stimulate the Sertoli cells, facilitating spermatogenesis and development of secondary sex characteristics.
Sertoli cells also release inhibin.
