Implantation, placentation and hormone changes in pregnancy

Question 1

IMPLANTATION:
What is Day 5-6 classed as?

What is the maternal recognition of pregnancy?

What does this hormone do?

How long are these effects necessary for?

What are the 2 types of testing of β-hCG? What are they used for?

When are β-hCG levels maximal by?

Answer 1

• Window of Implantation
• Trophoblast cells producing β-hCG
• • Maintains CL for Progesterone production
  • Decidualisation (preparation of endometrium)
• Until Placental steroidogenesis takes over at WEEK 7-8
• 1. Qualitative testing of β-hCG in a Urinary pregnancy test
     
     2. Quantitative testing of Serum β-hCG for monitoring early pregnancy complications (Ectopic pregnancy, Miscarriage)
• 9-11 Weeks

Question 2

PLACENTA:
What are the properties that make it an efficient transfer site?

What’s its functional unit?

What are its functions?

What becomes the umbilical cord? What does the umbilical cord contain?

How does the Trophoblast invade into the Myometrium?

What becomes filled with the maternal blood?

What can a disorder of the Placenta lead to?

Answer 2

• Huge maternal uterine blood supply (low pressure), Large surface area in contact with maternal blood, Huge reserve in function
• Cotyledon
• • Steroidogenesis - Oestrogens, Progesterone, HPL, Cortisol
  • Nutrition (O2, Energy, Antibodies, Vitamins, Minerals)
  • Removal of waste (CO2, Urea, NH3, Minerals)
  • Immune barrier (Bacteria, Viruses, Drugs)
• Connecting stalk → Umbilical cord
  o 1 umbilical vein wrapped in 2 umbilical arteries
• First layer to invade is the Syncytiotrophoblast, then the Cytotrophoblast, followed by the EXTRAEMBRYONIC MESODERM (UMBILICAL VESSELS TRAVELS WITH THIS)
• The Trophoblastic Lacuna

- • Miscarriage
• Pre-eclampsia
• Hydatidiform mole
• Placental Insufficiency
• Transfer of other substances - Drugs, Toxins, Infections (HIV, Syphilis)

Question 3

AMNIOTIC CAVITY:
What is its function?

What are the disorders of it?

How does a diabetic mother affect the amniotic sac?

Answer 3

• • Homeostasis - Temperature, Fluid, Ion balance
  • Vital for Development of certain structures - Limbs, Lungs
  • Protection - Physical barrier against ascending infections from vagina
• Polyhydramnios (too much fluid), Oligohydramnios (too little fluid), Premature rupture of membranes
• Lots of glucose is passed across the placenta to the foetus, causing it to produces a lot of urine (Polyuria) = Too much amniotic fluid = Polyhydramnios

Question 4

HORMONAL CHANGES:
Progesterone:
When does the placenta take over its production from the CL?

What are its effects during pregnancy?

Oestrogen:
What are 3 types? Which is the strongest and weakest?

How is it produced in the placenta?

What are its effects during pregnancy? How does it relate to weight gain during pregnancy?

Cortisol and CRH:
When do they start being produced more?

What are the effects of Cortisol during pregnancy?

What are the effects of CRH during pregnancy?

Human Placental Lactogen (HPL) and Prolactin:
What are effects of HPL during pregnancy?

What is the effect of Prolactin during pregnancy?

Answer 4

• Week 7-8
• • Smooth muscle relaxation - Uterine Quiescence
  • Breast development
  • Mineralocorticoid effect - Cardiovascular changes

• OesTRIOL (E3) > OestraDIOL (E2) > OestrONE (E1)
• Can’t make oestrogens on its own, so it relies on the Androgens (Testosterone) from the Foetus and Maternal adrenal glands
• • Uterine hypertrophy (≠ HYPERPLASIA)
  • Breast development
  • Cardiovascular and Metabolic changes - INSULIN RESISTANCE
  o This insulin resistance is the reason for weight gain during pregnancy

• From the 2nd Trimester
• • Metabolic changes - INSULIN RESISTANCE
  • Foetal Lung maturity
• Placental biological clock for labour initiation

• • Metabolic changes - INSULIN RESISTANCE
  • Role in Lactation
• Breast development for Lactation