Maternal Changes in Pregnancy

Question 1

Hormonal changes:
How does the production of maternal steroids change?

What are the Placental and Foetal steroids? What are their effects?

What are the Placental hormones?

What are the Maternal and Foetal Pituitary hormones?

Answer 1

• Placenta takes over production from CL after week 7
• Progesterone, Oestrogens (Oestradiol, Oestriol)
  o They increase effects on the RAAS, Respiratory centre, GI tract, Blood vessels, Uterine Myometrium contractility
• hCG, hPL, GH
• GH, T3/4, Prolactin, CRF

Question 2

ENERGY BALANCE:
What is the ideal weight gain?

Why is there a gain in fat and protein stores?

Glucose Metabolism:
How is it during the 1st Trimester?

How does it change in the 2nd Trimester? How does this produce Foetal reserves?

Water Balance:
What hormones act on the RAAS? What does this cause?

How much water is gained during pregnancy?

What is a normal consequence of an overactive RAAS during pregnancy?

Answer 2

• <13kg
• • Increased consumption and reduced use
  • Mainly laid down in Anterior Abdominal wall
  • Used later in pregnancy and post-partum

• ↑β-cells = ↑Insulin = ↑Maternal reserves and ↓Plasma Glucose
• hPL causes Insulin resistance = ↑Plasma Glucose
  o More crosses placenta for Foetus to store in its Liver

• Oestrogen and Progesterone, causing Sodium retention, resetting of Osmostat, decreased Thirst threshold, decrease in Plasma oncotic pressure (Albumin)
• 8.5L
• Hypokalaemia

Question 3

RESPIRATORY:
What are the changes that occur? What does it lead to?

What is the main reason for these changes?

Answer 3

• Increased sensitivity to CO2 and Increased Thoracic mobility (RIBCAGE DISPLACED UP AND FLARED OUTWARDS) = Deeper, Faster breathing = ↑pO2 and ↓pCO2 = Alkalosis
• It increases the gradient for more effective Placental gas transfer

Question 4

PLASMA COMPOSITION:
How does the Maternal blood change? What does this increase as a result?

What does this increased plasma volume lead to?

How does its coagulability change? What is a potential risk with this?

How is Foetal blood different from Maternal blood? What’s the importance of this?

How does smoking affect placental transfer? What does this lead to?

Answer 4

• Increased plasma volume and RBC mass, which increases the efficiency of gut Iron absorption
• Haemodilution = APPARENT ANAEMIA as Hb concentration falls
• Increased WBCs and Clotting factors makes the blood Hypercoagulable = Increased Fibrinogen and Risk of Thrombosis
• Increased Hb and of a different type = Increased O2 binding = Oxygen taken from Maternal Blood
• It increases Maternal carboxy-Hb, which is more permanent and reduces the increased binding = Foetal Hypoxia

Question 5

CARDIOVASCULAR:
Why do the ECG and Heart sounds change?

How does CO change?

How do the blood vessels change?

What occurs to assist in heat loss? What does cause to appear?

Answer 5

• Expanding Uterus pushes up against the heart
• Increased CO (↑HR and SV) as early as Week 3 to a max of 40% at Week 28
• Vasodilation by steroids leads to ↓TPR = ↑Flow to Uterus and Placenta, Muscle, Kidney, Skin
• Neonangiogenisis = Appearance of Spider Naevi

Question 6

GI TRACT:
What is the effect of steroids on it? What do they lead to?

How is Folic acid recommended?

What is Folic acid needed for?

What is a deficiency in Folic acid linked to?

Answer 6

• • Increased Appetite and Thirst, Reduced GI motility = Constipation
  • Relaxed LOS = Acid reflux (GORD)
• Folic acid supplementation taken every day up to Week 12
• DNA production, Growth, and Blood cells
• Spina Bifida (NTD)

Question 7

URINARY TRACT:
How does it change? What does increase the risk of?

How does the Kidney change? What does this cause?

Why do pregnant women micturate more frequently?

Answer 7

• Dilation and Relaxation of Urinary tract, leading to increased risk of UTI
• Increased Renal blood flow = ↑GFR = ↑Clearance of Creatinine, Urea, Uric acid
• Uterus grows and puts pressure on the Bladder

Question 8

REPRODUCTIVE TRACT:
How does the Uterus change?

How does the Cervix change?

Answer 8

• Huge increase in Muscle mass, Blood flow, and Volume
• • Increased Vascularity, Tissue softens
  • Increased Mucous production

Question 9

POST-PARTUM RETURN:
What happens when the Placenta is removed?

What does this drop in steroids allow for?

What happens with the Uterus after delivery?

Answer 9

• Rapid fall in steroids
• Allows for the action of ↑Prolactin on breast = Lactation
• Uterine muscle quickly loses oedema, but contracts slowly (Never returns to original size)