13.0 Maternal Adaptations to Pregnancy Flashcards

Question 1

Q

In humans, what changes occur to the sex hormones in late gestation?

Answer

A

Oestrogen to progesterone ratio ↑ Oestrogen ↑ Progesterone stays stable (different to animals where progesterone decreases)

Question 2

Q

What does the change in oestrogen:progesterone ratio in late gestation induce?

Answer

A

Lactation and parturition

Question 3

Q

What hormones (other than sex hormones) increase during pregnancy?

Answer

A

1) Prolactin 2) Placental lactogen/placental variant GH 3) PTH 4) Cortisol and aldosterone (adrenal cortex) - These do not actually increase. Just more are recorded in blood because of an increase in globulins (stimulated by oestrogen)

Question 4

Q

What happens to prolactin levels during pregnancy?

Answer

A

Increases (pituitary gland enlarges 30-50%)

Question 5

Q

What does increase in prolactin cause?

Answer

A

Mammary gland changes

Question 6

Q

What are the complications that can occur with enlargement of pituitary during pregnancy?

Answer

A

1) Blindness can occur if there is pre-existing acromegaly 2) Post-partum haemorrhage can cause Sheehan syndrome (Simmond disease)

Question 7

Q

What is Sheehan syndrome (Simmond disease)?

Answer

A

Ischaemia of the anterior pituitary due to compromised blood supply from the venous plexus. Sufferers do not lactate and do not resume menstrual cycle

Question 8

Q

What is the average weight gain in pregnancy?

Answer

A

12.5kg (Due to foetus + placenta + fat)

Question 9

Q

What are the CVS changes in pregnancy?

Answer

A

1) ↑ Blood volume 2) Changes in blood composition - ↑ RBC (but greater ↑ in plasma → overall haemodilution) - ↑ clotting 3) ↑ CO 4) No change to BP

Question 10

Q

Features of pre-eclampsia:

Answer

A

1) HTN ( >140/90mmHg) 2) Non-dependent oedema (usually hands and face) 3) Proteinurea

Question 11

Q

What are the renal changes in pregnancy?

Answer

A

1) ↑ GFR 2) ↑ Na⁺ reabsorption 3) ↑ erythropoietin

Question 12

Q

What are the respiratory changes in pregnancy?

Answer

A

1) ↓ compliance and FRC 2) ↑ tidal volume

Question 13

Q

What are the metabolic changes in pregnancy?

Answer

A

1) Maternal insulin resistance 2) ↓ gastric emptying and ↑ GIT transit time 3) ↑ liver metabolism

Question 14

Q

What are the behavioural changes in pregnancy?

Answer

A

EARLY ↑ food acquisition (cravings etc but also nausea/vomiting) LATE Fatigue Restlessness Nesting

Question 15

Q

What is the definition of a small infant?

Question 16

Q

What are the maternal factors that influence foetal size?

Answer

A

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Question 17

Q

How does placental size correlate to foetal size?

Answer

A

↑ placental size → ↑ foetal size

Question 18

Q

What are the foetal factors that influence foetal size?

Answer

A

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Question 19

Q

What is the mechanism that explains why foetal Hb has a higher affinity for oxygen than adult Hb?

Answer

A

Human foetal Hb has a ↓ affinity for 2,3 DPG therefore has an ↑ affinity for O₂ binding

Question 20

Q

What are the differences between foetal circulation and adult circulation?

Answer

A

• Differs from adult circulation in the following ways: 1. Supplies the placenta - 55% of combined cardiac output goes to the placenta - Placenta has low resistance - Total peripheral resistance and blood pressure are lower in fetuses 2. Bypasses the lungs - Only 7-13% of cardiac output goes to lungs - Pulmonary vascular resistance is high in utero 3. Has two shunts i. Foramen ovale (FO) ii. Ductus arteriosus (DA) - Achieves pulmonary bypass - R + L heart beat in parallel in fetus 4. Total CO (both ventricles) =4x higher than in adults

Question 21

Q

What hormone is responsible for maturation of foetal tissue before birth?

Answer

A

↑ glucocorticoids (cortisol)

Question 22

Q

What induces parturition?

Answer

A

↓ progesterone:oestrogen ratio → ↑ prostaglandin synthesis (in humans progesterone stays the same but oestrogen increases)

Question 23

Q

What fetal hormones are released to begin parturition induction?

Answer

A

1) Cortisol → fetal tissue maturation 2) DHAS → rapid ↑ in maternal oestrogen

Question 24

Q

What maternal hormones are released to begin parturition?

Answer

A

1) Oestrogen → cervical ripening and uterine contractions 2) CRH → ↑ fetal adrenal DHAS secretion, ↑ PG availability in uterus + ↓ myometrial contractions (↑cAMP)

Question 25

Q

Mechanism of myometrial contractions:

Answer

A

1) ↑ oestrogen (↓P:O) → ↑ actin + myosin expression and CAP proteins 2) ATP + myosin light chain kinase (MLCK) needed 3) Ca²⁺ → + CAM → + MLCK 4) ↑Ca²⁺ influx → contractions

Question 26

Q

Define uterotonins

Answer

A

Substances that stimulate uterine contractions

Question 27

Q

How are uterine contractions coordinated?

Answer

A

Via gap junctions

Question 28

Q

What contractions precede labour?

Answer

A

Braxton-Hicks contractions

Question 29

Q

What are the three stages of labour?

Answer

A

Stage 1 = uterine activity + cervical dilation - 10-12hrs (primagravida) / 6-8hrs (multigravida) - Blood + mucus - Cervix → 10cm - +ve feedback contractions Stage 2 = expulsion of fetus - 45-120mins (primagravida) / 15-45mins (multigravida) - Voluntary effort needed - Most dangerous stage for baby - Mother’s BP ↑ (30/25mmHg) Stage 1 = placental expulsion - 10mins - Uterus continues to contract until placenta is removed - Retained placenta = risk of haemorrhage

Question 30

Q

Factors influencing timing of delivery?

Answer

A

1) Light/dark cycle 2) Food supply 3) Infection 4) Climate (temp/rainfall) 5) Other animals who are parturient 6) Danger/disturbance

Question 31

Q

Indications for Caesarian?

Answer

A

1) Cephalic-pelvic disproportion 2) IUGR 3) Previous C-section 4) Uterine damage

Question 32

Q

Indications for induced delivery?

Answer

A

Water broken >72hrs Overdue >10days

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13.0 Maternal Adaptations to Pregnancy Flashcards

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