Physiological changes during pregnancy

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Questions and Answers

What role does Human Chorionic Gonadotropin (hCG) play in early pregnancy?

It stimulates ovulation in the ovaries.

It maintains the corpus luteum and prevents menstruation. (correct)

It prevents the production of progesterone.

It directly influences fetal growth and development.

At what stage of pregnancy do hCG levels peak?

After 30 weeks

At conception

Around 12 weeks (correct)

At 24 weeks

Which hormone is primarily responsible for stimulating trophoblast growth during the early stages of pregnancy?

Early Pregnancy Factor (EPF) (correct)

Gonadotrophin Releasing Hormone (GnRH)

Progesterone

Oestrogen

What physiological change does Gonadotrophin Releasing Hormone (GnRH) bring about during pregnancy?

It stimulates placental hCG production. Signup and view all the answers

What is the function of β-human chorionic gonadotropin in pregnancy?

It is used diagnostically to confirm pregnancy. Signup and view all the answers

What effect does increased progesterone have on the glomerular filtration rate during pregnancy?

Increases the filtration rate Signup and view all the answers

How does aldosterone influence salt absorption during pregnancy?

It increases salt absorption Signup and view all the answers

What physiological change during pregnancy helps prevent significant blood loss after the placenta detaches?

Hypercoagulability Signup and view all the answers

What is a standard difference in urinary levels for pregnant individuals compared to non-pregnant individuals?

Higher levels of protein and sugar Signup and view all the answers

How does a pregnant woman's oxygen utilization during exercise change?

Increases by 16% Signup and view all the answers

What common complication is associated with increased blood volume and pressure during pregnancy?

Varicose veins Signup and view all the answers

Which change in respiratory mechanics is most significant in pregnant women?

Compensation by deeper breaths Signup and view all the answers

What is a characteristic symptom of gestational hypothyroidism?

Persistent vomiting and weight loss Signup and view all the answers

What is the primary reason for the increased blood flow to the kidneys during pregnancy?

Enhancement of creatinine clearance Signup and view all the answers

Which hormone stimulates the production of T4 levels during pregnancy?

hCG Signup and view all the answers

What disorder is indicated by the symptom of pruritis and relates to leakage of bile salts during pregnancy?

Obstetric cholestasis Signup and view all the answers

What characteristic of the uterine muscle contributes to stronger contractions during labor?

Spiral muscle fiber arrangement Signup and view all the answers

What common misconception exists regarding breathlessness during pregnancy?

It is indicative of immediate health problems Signup and view all the answers

Which symptom is commonly associated with gestational diabetes?

Persistent thirst and hunger Signup and view all the answers

Which of the following statements regarding gastrointestinal changes in pregnancy is true?

Cravings vary with the trimester Signup and view all the answers

What consequence results from increased blood supply to the skin during pregnancy?

Pregnancy glow Signup and view all the answers

Which of the following hormones is primarily responsible for relaxing pelvic ligaments during pregnancy?

Relaxin Signup and view all the answers

What physiological change occurs in blood volume during pregnancy?

Increase from 2.6L to 3.8L Signup and view all the answers

Which hormone is secreted by the chorion at 3-4 weeks of pregnancy?

Estrogen Signup and view all the answers

What is the role of oestrogen in relation to fetal and maternal tissues during pregnancy?

Promotes tissue proliferation Signup and view all the answers

At what point does hCG peak during pregnancy?

9 weeks Signup and view all the answers

Which hormone primarily increases cortisol levels during pregnancy?

Corticotrophin RH Signup and view all the answers

What is a common effect of hormonal changes during pregnancy on the gastrointestinal system?

Decreased gut motility Signup and view all the answers

Which of the following changes in cardiac function primarily occurs around 13-14 weeks of pregnancy?

Increase in cardiac output Signup and view all the answers

What is the role of placental lactogen during pregnancy?

Preparing mammary glands Signup and view all the answers

What is a likely indication of unusual cravings such as coal or chalk during pregnancy?

Nutritional deficiency Signup and view all the answers

Which nutrient transfer mechanism is primarily used for glucose across the placenta?

Facilitated diffusion Signup and view all the answers

What is one risk associated with severe cases of hyperemesis gravidarum during pregnancy?

Dehydration Signup and view all the answers

What physiological change results from progesterone's effect on the urinary system during pregnancy?

Relaxation of smooth muscle Signup and view all the answers

What is a direct consequence of increased absorption of water in the gut during pregnancy?

Constipation Signup and view all the answers

Which hormone is primarily responsible for manipulating maternal insulin levels during pregnancy?

Human Placental Lactogen (hPL) Signup and view all the answers

What is the primary role of Relaxin during pregnancy?

Increase tendon flexibility Signup and view all the answers

Which hormone inhibits the development of follicles and ovulation during early pregnancy?

Progesterone Signup and view all the answers

What effect does human Chorionic Gonadotrophin (hCG) have on the body during pregnancy?

Maintains corpus luteum Signup and view all the answers

Which hormone is NOT involved in increasing serum calcium levels during pregnancy?

Human Placental Lactogen (hPL) Signup and view all the answers

The role of Prolactin during pregnancy primarily includes which function?

Regulating milk production Signup and view all the answers

Which hormone is critical for the decidualization process and nourishment of the embryo?

Progesterone Signup and view all the answers

Which hormone increases kidney function during pregnancy?

Renin Signup and view all the answers

Glucocorticoids during pregnancy primarily affect which of the following?

Increase in maternal glucose levels Signup and view all the answers

What is the impact of Thyroid Hormones (TH) during pregnancy?

Enhancement of glucose availability Signup and view all the answers

Study Notes

Physiological Changes in Pregnancy

Alpana Asurlekar, UM2010, adapted from Dr. Allyson Clelland's slides
Lecture plan to identify key hormones and endocrine organs for reproduction and pregnancy maintenance
Learning objectives: Identify the role of hormones in pregnancy, explain hormone level changes during pregnancy, and identify the role of hormones on other body systems

Maintenance of Pregnancy

Initial pregnancy maintenance involves the corpus luteum releasing hormones after ovulation
Key hormones:
- Human Chorionic Gonadotrophin (hCG)
- Progesterone
- Oestrogen
Placenta eventually takes over hormone production from the corpus luteum after ovulation

Human Chorionic Gonadotrophin and Gonadotrophin Releasing Hormone

GnRH increases over 24 weeks, stimulating placental hCG production
Secreted by the developing placenta
Maintains the corpus luteum (CL) for 6-7 weeks, preventing menstruation and embryonic loss
Peaks around 12 weeks, potentially linked to morning sickness
Stimulates testosterone production from the fetal adrenal medulla for external genitalia development

Hormonal Changes

Early Pregnancy Factor (EPF) is detected in the bloodstream shortly after conception, acting as an immunosuppressant and stimulating trophoblast growth during the peri-implantation period.
β-hCG is diagnostic and used along with ultrasound to confirm pregnancy.

Maternal Hormonal Changes

Increase:
- Progesterone (P) for pregnancy maintenance
- Oestrogen (E)
- Human Chorionic Gonadotrophin (hCG)
Decrease:
- Gonadotrophin Releasing Hormone (GnRH)
- Follicle Stimulating Hormone (FSH)
- Luteinising Hormone (LH)

Hormonal Changes in the Mother

Increase:
- Human Placental Lactogen (hPL) increases maternal insulin levels and serum glucose, promoting fat storage.
- Relaxin increases tendon flexibility for fetal growth and birth, relaxing the uterus, and dilating the pubic symphysis and cervix for birth.
- Adrenocorticotrophic Hormone (ACTH) stimulates the adrenal cortex.
- Thyroid Stimulating Hormone (TSH) stimulates TH, impacting glucose availability and growth.
- Vasopressin affects smooth muscle constriction in blood vessels, uterus, and mammary glands.
- Prolactin inhibits ovulation and controls salt and water movement, facilitating milk production.
- Thyroid hormones (TH) increase maternal basal metabolic rate

Changes Continued

Renin increases kidney function
Erythropoietin increases blood cell production
Vitamin D increases calcium absorption
Parathyroid Hormone (PTH) increases serum calcium levels
Glucocorticoids increase maternal glucose levels

Roles for Progesterone in Early Pregnancy

Inhibits uterine contractions, preventing embryonic loss
Nourishes the embryo and maintains the endometrium

Progesterone in Later Pregnancy

Breast development with increased gland size and number
Uterine expansion
Blood vessel capacity increases
Constipation related to slowed GI tract
Glucose regulation modifications
Progesterone promotes prostaglandin precursors needed for labor

Roles of Oestrogen in Pregnancy

Secreted by the placenta (first) and influenced by fetal and maternal androgens (adrenal glands)
Pelvic ligament relaxation supporting uterine expansion
Supports the proliferation of fetal and maternal tissues (enlarging uterus, breasts, and external genitalia)
Increases cortisol levels

Hormonal Changes (Summary)

hCG is detectable at 8 days, peaking at 9 weeks and decreasing after
Chorion secretes oestrogen (3-4 weeks) and progesterone (6 weeks)
Relaxin is produced by the placenta, increasing during pregnancy for body preparation for birth
Placental lactogen prepares mammary glands for milk production
Corticotrophin releasing hormone (CRH) affects glucose availability

Cardiovascular System

Blood volume increases from 2.6L to 3.8L
Cardiac output increases due to increased stroke volume (SV) and normal heart rate
Blood pressure decreases
Blood cells increase due to erythropoietin
Blood supply increases to kidneys and skin
Hypercoagulability (increased risk of thrombosis) is present
Folic acid supplements are needed for the first 12 weeks to prevent anemia

Cardiovascular System (Cont'd)

Oxygen use increases by 16%
Alveolar ventilation increases
Tidal volume increases by 40% (700mL to 500mL)
Deeper breaths increase gaseous exchange efficiency
Lung squashing is compensated by deeper breaths

Reproductive System

Uterus growth is due to hypertrophy/hyperplasia of tissues
Spiral arrangement of muscle fibers in the upper uterus
Circular arrangement in the lower uterus
Blood vessels in the uterus close during contraction

Gastrointestinal System

Cravings and food preferences vary by trimester, possibly influenced by social factors
Nausea and sensitivity to tastes/smells are common
Cardiac sphincter relaxes, increasing reflux risk
Decreased gut motility and acid secretion can lead to constipation
Hormones influence glucose availability, growth, and fat deposition

Gastrointestinal System (Cont'd)

Increased water absorption from slowed GI motility contributes to constipation
Requires 300 extra calories per day in the third trimester, and additional protein intake
Hospitalization can occur in severe cases of hyperemesis gravidarum, related to the increased need for extra calories, protein, and water intake

Renal System

Urinary collection system expands (calyces)
Renal blood flow and glomerular filtration rate increase
Protein and sugar levels in the urine increase
Increase in water retention is present
Progesterone causes smooth muscle relaxation, influencing water retention and salt absorption

Additional Considerations

Varicose veins and edema are common
Bladder infections and other mild infections are possible
Leg cramps can occur
Breast development and growth are significant changes
Venous valves malfunction with increased weight and blood pressure, linked to progesterone effects
Immune system changes, and pressure exerted on veins
Progesterone and estrogen stimulate mammary gland duct development

Fetal Requirements and Maternal Responses

Fetal requirements are addressed via appropriate maternal responses including nutrition, waste clearance, and pregnancy maintenance and maturation
These maternal responses include vasodilation, increased respiration, altered insulin resistance, and more renal glomerular filtration

Problems with Pregnancy (Matching)

Gestational Diabetes: Symptoms similar to normal pregnancy (tiredness, mood changes) and related to insufficient insulin production.
Gestational Hypothyroidism: Persistent vomiting, weight loss, tremors, related to increased T4 levels stimulated by hCG.
Obstetric Cholestasis: Itching (pruritis) and leakage of bile salts related to multiple pregnancies.
Gestational Transient Thyrotoxicosis: Thirst, hunger, increased blood sugar levels related to insufficient insulin production.

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