Pregnancy Physiology and Complications - Test 1 Flashcards
What are the five main functions of the placenta?
- Hormone production
- Protection from the maternal immune system
- Protection against infection
- Fetal nutrition
- Gas exchange
Which hormones are produced by the placenta?
hCG
Progesterone
Estrogen
Human placental lactogen (hPL)
Which placental hormone triggers hyperventilation in the mom?
Progesterone
Describe the subunits of the hCG glycoprotein and how they are physiologically and clinically relevant.
alpha subunit of hCG is identical to that of LH, FSH (helps to downregulate the HPG axis during pregnancy)
alpha subunit also mimicks TSH –> increased thyroid hormone synthesis in mom (but there is also increased thyroid binding globulin synthesis in the liver so free levels and TSH remain normal in most pregnant ladies)
beta subunit of hCG is specific to hCG
Which hormone triggers the nausea and vomiting common in early pregnancy?
hCG
What are the main physiologic effects of estrogen during pregnancy?
Estrogen causes enlargement of the uterus, breasts, and mammary ducts (its the hormone responsible for breast tenderness during pregnancy)
After fertilization, the corpus luteum is rescued by hCG, which then begins to synthesize _________ (hormone) until the syncitiotrophoblasts take over at ~7-10 weeks gestational age.
progesterone
By what mechanism does mifepristone terminate early pregnancy?
It is a progesterone antagonist; progesterone is necessary to maintain early pregnancy
Describe the physiologic effects of hPL in the fasting state and fed state, respectively.
Fasting state: hPL stimulates pancreatic secretion of insulin -> accelerated starvation w/ hypoglycemia (increased lipolysis helps maintain energy source for mom)
Fed state: hPL causes relative maternal insulin resistance -> higher circulating glucose levels to facilitate transfer to the fetus (worse in women w/ diabetes)
What is the recommended weight gain for a woman of normal BMI with a singleton pregnancy? What about for an obese woman?
Normal BMI: 25-35 pounds
Obese: 11-20 pounds
Name the two hormones that are responsible for loosening the connective tissue of the pelvic floor and vagina.
Relaxin and progesterone
What does the fundal height (in cm) correspond to? At 20 weeks gestation, the fundal height should be at the level of the ________ (anatomic landmark).
Fundal height corresponds to gestational age. At 20 weeks, fundal height should be at the level of the umbilicus.
What happens to aldosterone levels during pregnancy? What are the physiologic consequences of this?
Aldosterone levels increase –> fluid retention
Describe a normal arterial blood gas for a pregnant women.
pH: 7.4 - 7.45
pO2: 100mmHg (same as non-prego)
pCO2: 27 - 32 mmHg (vs. 40 in non-prego)
Bicarb: 18 - 21 mEq/L (vs. 24 in non-prego)
Describe the changes to respiratory rate, minute ventilation, and functional residual capacity that occur during pregnancy.
Why are pregnant women at increased risk of developing pyelonephritis?
Progesterone causes smooth muscle relaxation –> dilation of renal pelves, calyces, ureters –> increased stasis –> pyelonephritis
Would you expect creatinine levels to rise, or fall during pregnancy as compared to when not pregnant?
They should decrease because of increased renal blood flow (and GFR) due to relaxation of renal artery smooth muscle from progesterone.
Creatinine should be 0.7 or less in a pregnant woman.
Describe the normal physiologic effects on the cardiac system that occur during pregnancy.
Progesterone and relaxin dilate smooth muscle –> decreased systemic vascular resistance
Cardiac changes: resting HR increases, stroke volume increases, therefore cardiac output increases
Your pregnant patient comes in for a routine prenatal visit and has a BP of 146/96. She has no Hx of chronic HTN. Is this normal for a pregnant gal?
Not normal, BP should be low during pregnancy due to the smooth muscle effects of progesterone and relaxin. This is concerning for preeclampsia.
When supine, the uterus can pinch the ______, leading to decreased cardiac output and hypotension (this is why pregnant women should not lie on their backs! Left lateral decubitus position is best)
IVC
Describe the normal hematologic changes that occur during pregnancy.
Blood volume increases by 40-50%, but RBCs only increase 20-30% —> physiologic anemia (dilutional anemia); Hct in pregnant women should be >32%
Pregnancy causes a state of hypercoagulability due to increased hepatic production of coagulation factors. The uterus also compresses veins –> stasis –> increased risk for DVT, PE
Moms who are red cell alloimmunized against _____ antigens on fetal red cells can cause fetal anemia, which if untreated can lead to ______ _______.
Rh-D antigens
untreated fetal anemia can lead to hydrops fetalis (skin edema, ascites, pericardial/pleural effusions, high output cardiac failure, kernicterus after birth from hemolysis–> hyperbilirubinemia)
How does one prevent red cell alloimmunization?
Rhogam (Rh-D immune globulin) - it binds to and masks any fetal red cells in maternal circulation
Define gestational diabetes.
A state of carbohydrate intolerance during pregnancy
Women with multiple risk factors for gestational diabetes should be screened at their first prenatal visit. What are the risk factors for gestational diabetes and what screening tests are used for this?
Risk factors:
BMI >25
Age >25
Prior Hx of abnormal glucose tolerance
Family Hx of macrosomic infant
Family Hx of diabetes
Hispanic, Native American, African, South or East Asian, Pacific Islander ancestry
Screen with:
Random glucose or A1c or oral glucose tolerance test
At what gestational age is it most effective to screen pregnant women for gestational diabetes?
Between 24 and 28 weeks gestation
Name some effects that maternal hyperglycemia have on the fetus.
Fetus will have a lot of insulin, which after birth can cause hypoglycemia
Insulin also acts like a growth factor –> macrosomia
It also causes fat distribution to the abdomen, neck, shoulders –> shoulder dystocia –> Erb’s palsy
What is the management for gestational diabetes?
Nutritional counseling: reduce simple carbohydrate intake and eat smaller meals more frequently
Medications:
Insulin (catebory B)
Metformin (category B)
Glyburide (category C)
Patients w/ gestational diabetes have a 50% risk of getting T2DM within ___ years, so all women that had gestational diabetes should be screened with a 2-hour OGTT ____ to ____ weeks postpartum
50% chance of getting T2DM within 5 years
do a 2 hour oral glcose tolerance test 6-8 weeks postpartum
What is the difference between chronic hypertension in a pregnant women and gestational hypertension?
Chronic hypertension is when they were diagnosed before 20 weeks gestation
Gestational HTN is when they are diagnosed after 20 weeks gestation
Peripheral edema, hand swelling, puffy eyes, cerebral edema, headache, RUQ pain in a pregnant woman.
This is a classic presentation of…? Describe the pathogenesis of this disease.
Preeclampsia
Pathogenesis: abnormal development of placental vessels from messed up trophoblastic invasion of uterine spiral arterioles -> endothelial dysfunction and abnormal control of vascular tone -> increased systemic vascular permeability
What are the subtypes of preeclampsia? Describe the distinguishing features of each.
- Preeclampsia without severe features
- BP 140/90 +
- Urine protein 300+ mg/24 hrs
- Preeclampsia with severe features
- BP 160/110 +
- Organ dysfunction (elevated creatinine, elevated LFTs, etc.)
- Eclampsia is a subtype of preeclampsia with severe features
- Headache
- Vision changes
- Seizures
- HELLP is another subtype (Hemolysis, Elevated Liver enzymes, Low Platelets)
Your patient has eclampsia and you want to treat her seizures. How do you do it?
Magnesium sulfate
What is the treatment for preeclampsia?
Deliver the little shit
What is the differential diagnosis for 2nd/3rd trimester bleeding?
2nd/3rd trimester bleeding is usually due to abnormal placentation: placenta previa, placenta accreta, or placental abruption
What is placenta accreta?
When the trophoblasts of the fetus invade too deep (into the myometrium of the uterus).
What is placenta previa?
When the placenta covers (either completely or partially) the internal cervical os. With cervical dilation, the placental bed can be exposed —> massive hemorrhage
What is placental abruption?
Premature separation of the placenta from the uterus -> bleeding of spiral arterioles in the decidua -> blood splits the decidua -> separation of the placenta from the uterus, compromising the fetus
Name four risk factors for placental abruption and three complications of it.
Risk factors:
- Smoking
- Hypertension
- Cocaine
- Trauma
Complications:
- Fetal death
- DIC
- Fetal asphyxia/hypoxia
Should you do a cervical exam on a woman to evaluate for 2nd or 3rd trimester bleeding?
Not until you’ve done ultrasound to rule out placenta previa.
Is ultrasound a good test to see placental abruption?
Not really - hard to visualize it
Define labor.
Define preterm labor.
Labor is >2cm dilated and >90% effaced
Preterm labor is labor at <37 weeks gestation
Name three causes of preterm labor.
- Infection/inflammation
- Abruption
- Uterine overdistension (from multiple gestations or polyhydramnios)
Name five risk factors for preterm delivery.
- Prior preterm delivery
- Multiple gestation
- Low SES
- Black race
- Chorioanmionitis
How do you evaluate a woman for possible preterm labor?
Speculum exam to evaluate for preterm premature rupture of membranes (PPROM): ferning pattern on microscopy and basic pH = rupture of membranes
Fetal fibronectin, which is released when trophoblastic cells are disrupted from the uterus, has an excellent negative predictive value - use it to rule out premature labor
What drugs should you give to a woman going into preterm labor?
Steroids to promote fetal organ and lung surfactant development: bethamethasone
Tocolytics prevent uterine contractions for a few days while the steroids work:
Nifedipine (Ca2+ channel blocker)
Terbutaline (beta agonist -> decreased intracellular Ca2+)
Magnesium sulfate (reduce intracellular Ca2+)
Name two successful methods and one unsuccessful method in preterm birth prevention.
Successful: IM or vaginal progesterone and smoking cessation
Unsuccessful: bedrest
Twin-twin transfusion syndrome is when __________ twins form abnormal connections between arteries and veins in the shared twin placenta -> one twin gets polyhydramnios and one gets oligohydramnios, potentially leading to growth restriction (donor), cardiac failure (recipient), fetal hydrops (recipient).
monozygotic
Ultrasound estimated fetal weight < _____ percentile is suggestive of intrauterine growth restriction (IUGR)
10th percentile
Estimated fetal weight by ultrasound of >90th percentile is suggestive of _________.
macrosomia
Study the risks for stillbirth:
This class fucking sucks
Name a safe medication used to treat nausea and vomiting of early pregnancy.
Vitamin B6 and doxylamine (unisom)
