Maternal Physiology Flashcards
When does progesterone production switch from corpus luteum to placenta?
10 weeks
What makes
- hCG
- Estrogen
- Relaxin
- Syncytiotrophoblasts
- Placenta
- Corpus luteum and placenta
4 main CV signs you might see during pregnancy
Decreased BP
Physiologic anemia
Enlarged heart, displaced left and upward on CXR
Systolic ejection murmur
What happens to
1. Blood volume
2. CO
3 SVR
- Increases
- Increases
- Decreases
Most changes occur in what trimester?
Begin in early trimester, peak in SECOND trimester and plateau until delivery
What happens to
1. plasma volume
2. RBC mass
Why?
- Increases
2. Increases (increased erythropoietin levels, need iron)
Which increases more, plasma volume or RBC mass? What is the result of this?
Plasma volume increase > RBC mass increase
Results in physiologic anemia of pregnancy (<105g/L)
CO increases due to…
Increased stroke volume (esp early pregnancy) Increased HR (esp 3rd trimester) Normally this is well tolerated, but pregnancy is a functional stress test so many be hard on a diseased heart
What happens to SVR? Why?
Decreases Placenta functions as a high flow, low resistance shunt Also vasodilation (decreased response to AII, and increased estrogen)
How does BP change over the course of a pregnancy?
Decrease begins in early pregnancy, reaches lowest at 24 weeks, then returns to pre-pregnancy levels by term
Supine hypotensive syndrome
Common! But also occurs with sitting or standing
Caused by compression of IVC by the uterus
Results in a decreased venous return and preload, decreasing the CO
Most women can compensate with increasing the PVR, but some cannot
Symptoms of supine hypotension in
- Mother
- Fetus
- Faint, light-headed, SOB, dizzy
2. Drop in HR as decreased O2 supply (fetal distress)
How do you treat supine hypotension?
When lying down, lie on left side
Uncross legs
Compression stockings
Keep calf muscles pumping when standing for prolonged periods of time
Why do pregnant women get a systolic ejection murmur?
Flow murmur due to increased CO across valves
When does the uterus stop being a pelvic organ?
At 12 weeks
2 main goals of the respiratory changes in pregnancy
Enhance oxygen delivery (oxygen consumption increases in pregnancy)
Eliminate excess CO2 from fetus
Resp maternal symptoms
Nasal stuffiness
Nosebleeds (epistaxis)
Dyspnea
How does the diaphragm change in pregnancy?
Elevated diaphragm
Widening of the subcostal angle
What hormone causes the SOB? How does it work?
Progesterone!!
Increases central chemoreceptor sensitivity to CO2
Results in increased minute ventilation via increased tidal volume
3 anatomic changes in the urinary tract
Dilated ureters
Dilated renal pelvis
Increased kidney size
What 2 things cause the anatomical changes in the urinary tract
Progesterone smooth muscle relaxation
Mechanical compression by uterus at pelvic brim
What side of the urinary system is more effected? Why?
Right side more than left
Because the uterus is slightly rotated to the right by the sigmoid colon
What happens to
- Renal plasma flow
- GFR
- Serum creatinine and urea
- Increases
- Increases
- Decreases
5 Common symptoms in GI
Nausea and vomiting (morning sickness) GERD Constipation Hemorrhoids Gall stones
2 main causes of GI signs and symptoms
Progesterone smooth muscle relaxation (LES relaxes, decreased GI motility and gall bladder contractility)
Mechanical displacement of GI tract due to enlarging uterus (elevation of stomach (GERD), displacement of colon)
Why do you not want to use general anaesthetic in pregnant women?
Increased risk of aspiration
Because of GI changes
2 main hormones responsible for the nausea and vomiting
Progesterone (delayed motility, reflux) Beta hCG (higher levels = worse, as levels plateau at 10-12 weeks it improves)
Hyperemesis gravidarum
Prolonged, severe nausea and vomiting
May require IV fluid and hospital admission
Hemorrhoids due to…
Constipation (decreased motility, increased water reabsorption)
Increased venous pressures due to obstruction of venous return by enlarging uterus
Postpartum blues vs depression
Blues: very common, usually resolves by day 10, give support and reassurance
Depression: requires medical attention
