Chapter 13 OB - Pregnancy: Duration, Trimesters, Hormonal and Physiological Changes

What is the duration of pregnancy?

Pregnancy lasts 40 weeks or 280 days from the last menstrual period, or 266 days from conception.

How is pregnancy divided in terms of trimesters?

1st trimester: 0-13 weeks 6 days;

2nd trimester: 14 weeks 0 days - 27 weeks 6 days;

3rd trimester: 28 weeks 0 days - 40 weeks 6 days.

What hormonal changes promote uterine growth during the first trimester?

Estrogen and progesterone promote uterine growth.

How does the weight of the uterus change during pregnancy?

The uterus increases from 4g (nonpregnant) to 1200g (gestation term).

What is the size of the uterus at 12 weeks of gestation?

At 12 weeks, the uterus changes from a nonpregnant pear shape to a spherical/globular shape.

When can the uterus be palpated above the symphysis pubis?

between 12-14 weeks of gestation

What occurs to the fundal height between weeks 38-40 of gestation?

Fundal height decreases as the fetus descends into the pelvis (lightening).

What is Braxton Hicks contraction?

Intermittent, irregular, painless uterine contractions that enhance blood flow through the intervillous spaces.

What is the average rate of blood flow through the uterus by term?

The average rate of blood flow through the uterus is 450 to 650 mL/min by term.

What is the uterine souffle?

A rushing or blowing sound of maternal blood flowing through uterine arteries to the placenta, synchronous with the maternal pulse. (Answer)

What is ballottement?

Movement of the unengaged fetus, felt by tapping upward on the cervix, causing the fetus to rise and then sink.

What is quickening in pregnancy?

first recognition of fetal movements, felt as flutters

• detected by multiparous women at 14-16 weeks

• nulliparous women at 18 weeks or later.

What is the Goodell sign?

A probable sign of pregnancy observed at the beginning of the 6th week, indicating increased vascularity, hypertrophy, and hyperplasia of the cervix.

What is the operculum?

The formation of a mucous plug in the cervix, rich in immunoglobulins, acting as a barrier against bacterial invasion. (Answer)

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What is Chadwick sign?

Increased vascularity resulting in a violet-blue color of the vaginal mucosa and cervix, evident at 6-8 weeks.

What is leukorrhea?

A copious mucoid discharge that occurs in response to cervical stimulation by estrogen and progesterone.

What changes occur in the vagina during pregnancy?

The vaginal mucosa thickens, connective tissue loosens, and smooth muscle hypertrophies to prepare for labor.

What are striae gravidarum?

Stretch marks that appear on the outer aspects of the breasts during pregnancy.

What is Lactogenesis Stage 1?

The initial stage of milk production that begins during pregnancy.

What is the significance of the corpus luteum during early pregnancy?

It produces estrogen and progesterone for the first 6-10 weeks until the placenta becomes the primary hormone source.

What is the effect of pregnancy hormones on the breasts?

Breasts experience fullness, heightened sensitivity, and changes in pigmentation in response to increased estrogen and progesterone.

What is the role of the vaginal microbiome during pregnancy?

It changes to prevent bacterial infection, increasing Lactobacillus and decreasing anaerobic bacteria.

What is the relationship between pregnancy and varicosities of the vulva?

Increased congestion and relaxed blood vessel walls during pregnancy can lead to edema and varicosities of the vulva.

What examination is used to measure uterine blood flow velocity?

Doppler ultrasound examinations

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What is funic souffle?

A sound synchronous with the fetal heart rate caused by fetal blood coursing through the umbilical cord.

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What hormonal changes occur in the ovaries during early pregnancy?

Ovulation does not occur; the corpus luteum produces estrogen and progesterone until the placenta takes over.

How much does total blood volume increase during the first half of pregnancy?

40-45%

When does blood volume peak during pregnancy?

At 32 weeks, increasing 1200-1600 mL above nonpregnant levels.

What happens to cardiac output during pregnancy?

It increases by 30-50%, peaking at 25-30 weeks.

What is the effect of pregnancy on blood pressure?

Blood pressure remains the same or slightly decreases despite increased cardiac output due to decreased systemic vascular resistance.

What is supine hypotensive syndrome?

A condition occurring when lying supine in the second half of pregnancy, causing vena cava compression and a reduction in cardiac output.

What factors can affect blood pressure during pregnancy?

Age, activity, health status, circulation rhythm, alcohol, smoking, anxiety, and pain.

What condition is characterized by a heart rate decrease and reduced cardiac output after 4-5 minutes?

Bradycardia

What causes dependent edema, varicose veins, and hemorrhoids during pregnancy?

Uterine compression of iliac veins and inferior vena cava increases venous pressure.

What structural heart adaptation occurs due to increased blood volume during pregnancy?

Slight cardiac hypertrophy.

How does the diaphragm change during pregnancy?

It elevates, shifting the heart upward and left.

What is the typical change in the position of the PMI (apical pulse) during pregnancy?

It shifts 1-1.5 cm upward and laterally.

What auscultatory changes are common in pregnancy by the end of the first trimester?

Audible splitting of S1 and S2.

What heart sound is common after mid-pregnancy due to rapid diastolic filling?

S3 heart sound.

What type of murmurs are common in the second and third trimesters of pregnancy?

Systolic ejection murmurs.

What is the increase in red blood cell mass by term during pregnancy?

250-450 mL (20-30%).

What results from the increase in plasma volume compared to RBCs during pregnancy?

Hemodilution, leading to physiological anemia.

What are the anemia criteria for the first and third trimesters of pregnancy?

Hgb <11 g/dL or Hct <33%.

What is the WBC count change during pregnancy?

Increases mainly in granulocytes and polymorphonuclear leukocytes.

What is the risk of thromboembolism during pregnancy?

5-6 times increased risk due to a hypercoagulable state.

What happens to maternal oxygen consumption by term?

Increases to ~40% above nonpregnant levels.

What structural changes occur in the rib cage during pregnancy?

Costal angle increases and rib cage flares outward.

What common respiratory issue occurs during the first and second trimesters?

Dyspnea.

What hormonal changes lead to nasal congestion during pregnancy?

Increased vascularity and capillary engorgement.

What gastrointestinal change is caused by increased progesterone?

Decreased smooth muscle tone and motility.

What common gastrointestinal issue occurs due to smooth muscle relaxation during pregnancy?

Constipation.

What is epulis, and when does it typically develop during pregnancy?

A red, raised gum nodule that bleeds easily, developing in the 3rd month.

What causes acid indigestion or heartburn during pregnancy?

Increased progesterone leading to esophageal regurgitation.

What is the effect of the enlarging uterus on the diaphragm?

It pushes the diaphragm upward by up to 4 cm.

What is the impact of pregnancy on tidal volume and minute ventilation?

Both increase, while respiratory rate remains unchanged.

What changes occur in the maternal gut microbiome during the third trimester?

Decreased bacterial diversity with increased proteobacteria and actinobacteria, and decreased faecalibacterium.

What is hyperemesis gravidarum?

Persistent or severe nausea and vomiting during pregnancy that may require medical attention.

What hormonal changes contribute to nausea and vomiting in pregnancy?

High levels of hCG and estradiol, along with prostaglandin E2.

What is Pica in the context of pregnancy?

Nonfood cravings such as ice or clay, often associated with iron deficiency anemia.

How does pregnancy affect gallbladder function?

Decreased muscle tone causes gallbladder distention, lower emptying, and bile thickening, increasing the risk of gallstones.

What are common urinary changes during pregnancy?

Increased frequency, urgency, nocturia, and bladder irritability.

What causes urinary stasis and infection risk during pregnancy?

Increased urine volume and slower urine flow due to anatomical changes.

What happens to renal function during pregnancy?

Renal plasma flow increases, glomerular filtration rate (GFR) rises, and renal function is best in a lateral recumbent position.

What is the effect of pregnancy on total body water?

Total body water increases by 6.5-8.5 L due to expanded blood volume, fetus, placenta, and amniotic fluid.

What is glucosuria and why can it occur during pregnancy?

Glucosuria may occur due to increased GFR exceeding tubular reabsorption capacity.

What is the significance of increased alkaline phosphatase in the third trimester?

It indicates changes in liver function and bile metabolism during pregnancy.

What skin changes are common during pregnancy?

Hyperpigmentation, including melasma, linea nigra, and striae gravidarum (stretch marks).

What is the impact of pregnancy on the musculoskeletal system?

Increased spinal curvature, abdominal muscle stretching, and joint instability due to hormonal changes.

What is diastasis recti abdominis?

A condition where abdominal muscles separate, causing protrusion at the midline, common in the third trimester.

What are common neurologic changes during pregnancy?

Headaches, lightheadedness, and sleep disturbances due to hormonal and physiological changes.

What changes occur in the thyroid gland during pregnancy?

Thyroid enlarges, T3 and T4 levels increase, and basal metabolic rate rises.

How does the pituitary gland change during pregnancy?

It enlarges due to increased prolactin-producing cells, with prolactin levels rising significantly.

What is the role of the placenta in the immune system during pregnancy?

It regulates maternal immune cell function to protect against infection and prevent rejection of the fetus.

What is the earliest biological marker of pregnancy?

hCG (human chorionic gonadotropin) is detectable in serum or urine 7-8 days after implantation.

What can abnormal hCG levels indicate?

High levels may indicate multiple gestations or abnormal pregnancy, while low levels may suggest miscarriage or ectopic pregnancy.

What are common symptoms of carpal tunnel syndrome during pregnancy?

Paresthesia, hand pain radiating to the elbow, and symptoms typically worsen in the last trimester.

What is the effect of lying down on fluid balance during pregnancy?

Lying down triggers diuresis as fluid returns to circulation, reducing dependent edema.

What is the common cause of leg cramps during pregnancy?

Altered calcium and phosphorus metabolism, along with uterine pressure on pelvic blood vessels and leg nerves.

What is the significance of increased vascularity in the bladder during pregnancy?

Increased vascularity raises the risk of urinary tract infections and trauma.

What is the common change in appetite during pregnancy?

Increased thirst may occur early due to greater water loss.

What is the effect of pregnancy on hair growth?

Hirsutism (excessive hair growth) is common, while scalp hair loss slows during pregnancy.

What is the relationship between pregnancy and sleep changes?

Increased fatigue and napping in the first trimester, with difficulty falling asleep and poorer sleep quality in later trimesters.

What are the common causes of headaches during pregnancy?

Hormonal changes, eyestrain, emotional tension, and may indicate complications like preeclampsia.

What is the common symptom of pruritus during pregnancy?

Itching caused by hormonal alterations and mechanical stretching of the skin.

What is the effect of pregnancy on the pancreas?

Insulin needs increase, and pregnancy hormones act as insulin antagonists, leading to β cell hypertrophy.

What is the common change in bladder tone during pregnancy?

Bladder tone may decrease, increasing capacity and leading to urinary incontinence in the third trimester.

What are common nail changes during pregnancy?

Nails may become thin and soft.

What is hirsutism?

Hirsutism is excessive or unusual hair growth, common during pregnancy.

What happens to fine hair growth after pregnancy?

Fine hair growth usually resolves after pregnancy.

What is the effect of pregnancy on scalp hair loss?

Scalp hair loss slows during pregnancy.

What is a common change in hair shedding postpartum?

Increased hair shedding is common postpartum.

What causes abdominal distention during pregnancy?

Abdominal distention causes forward pelvic tilt, decreased abdominal muscle tone, and increased weight bearing.

What spinal changes occur during pregnancy?

Spinal curvatures realign, increasing lumbar lordosis and causing compensatory cervicodorsal curvature.

What symptoms can result from spinal changes during pregnancy?

Aching, numbness, and weakness in upper extremities.

What pelvic joint changes occur during pregnancy?

Increased mobility of sacroiliac, sacrococcygeal, and pubic joints.

What is diastasis recti abdominis?

A condition where abdominal muscles stretch and separate, often occurring in the third trimester.

What are common causes of leg cramps during pregnancy?

Altered calcium and phosphorus metabolism, and uterine pressure on pelvic blood vessels and leg nerves.