Obstetric Physiology Flashcards by Lauren Lover

Most of the physiology changes that occur in early pregnancy are (hormonal/physical)

hormonal

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What hormones are involved in the hormonal changes that occur in early pregnancy?

Progesterone
Estrogen
Renin / aldosterone
Cortisol
Insulin

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Most physiologic and anatomic changes are designed to optimize conditions for fetus and prepare for delivery. Especially geared toward the delivery of ____ and _____

oxygen

nutrients

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How do you calculate the Expected Date of Delivery (EDD)

take the date of the last menstrual period
add 7 days to that date
count back 3 months

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___ is the first part of pregnancy to develop

placenta

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The placenta weighs ~ ___ at birth

1 lb

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The placenta is specialized for ____ and ____ ____ and keeps the fetus from being recognized as ____ by the maternal immune system

oxygen and nutrient delivery

“non-self”

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The endometrium’s blood supply comes from the ______.

With each new luteal phase, new ____ are created, which supply blood to the endometrium.

Basal Arteries

Spiral Arteries

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With each period, ____ are lost and the basalis makes new ones for the next cycle.

What happens to the spiral arteries when a pregnancy implants?

spiral arteries

the spiral arteries remain

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___ % of each heartbeat goes to the placenta

20%

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Once pregnancy is established, the spiral arterioles expand and become confluent, forming ____ for maternal blood flow to encounter the fetal umbilical capillaries.

pockets

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The placental barrier allows for (Passive/Active) transport of certain materials.

Passive

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___ cannot cross the placenta, but ___ can!

Large proteins

IgG (maternal immunity)

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By the 3rd trimester, the placenta receives ___% of the cardiac output.

20-25% (750 ml/min)

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T/F: The blood supply to the placenta is susceptible to vasoactive medications

F: they are refractory to vasoactive meds

***This is why a woman can bleed out so rapidly w/ placenta abruption

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The placenta uses (More/As much/Less) O2 as the fetus because of its significant metabolic activity

As much

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What hormones does the placenta make?

HCG
progesterone
estrogen
placental lactogen
parathyroid hormone RP
Realxin 
corticotropin releasing hormone

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What does progesterone do?

What are some “side effects” of progesterone?

Maintains uterine lining, inhibits uterine contraction

Slows things down (constipation)

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What does estrogen do?

Maintain uterine lining

Stimulate mammary glands

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What does placental lactogen do?

What are some “side effects”?

Stimulate mammary glands
Supplies energy to fetus

Mimics growth hormone; promotes maternal insulin resistance; elevates glucose levels

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What does the parathyroid hormone RP do?

Increase Ca++

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What does relaxin do?

What are some “side effect”?

soften cervix
weakens pubic symphysis

Pelvic discomfort and double-jointedness

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What does corticotropin releasing hormones do?

What are some “side effects”?

Increase HR, BP, blood glucose
Stimulates partition

Acts like glucagon; increases POMC

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Placenta produces CRH –> What pituitary hormone is this promoting?

ACTH

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What is the result of the high levels or ACTH and cortisol levels?

Skin pigment changes - linea nigra - melasma * *can be permanent

During pregnancy, there is (increased/decreased) tone / vaso-relaxation. ___ decreases by 20% due to the low resistance of the placenta What can the the result of this change?

Decreased SVR Positional effects from Vena cava compression (dizziness)

In pregnancy blood volume increases ____-____% RBC mass increases ___-___% What can these changes mimic?

50-100% 25-40% ``` Anemia Relative anemia (physiologic, dilutional) ```

Changes in cardiac function occur are early as ____ weeks gestation, before many pts are even aware that they are pregnant

8 wks

What happens to the location of the cardiac axis during pregnancy?

Displaced cephalad Left axis deviation

Murmurs are present in > __%, which is usually due to increased ____ **Virtually all valves can be involved, especially aortic and pulmonary

96% | blood volume

What happens to HR during pregnancy?

Increases

There is a ___% increase in ventricular distention

25%

What are some alarming EKG changes that can occur during pregnancy?

Non-specific ST and T changes | Dysrrhythmias (hypokalemia)

T/F: LVH and mild pericardial effusion are common during pregnancy

During what trimester does BP decrease? When can you expect it to original level?

2nd End of pregnancy

____ d/o are common in pregnancy. When does this usually begin?

hypertensive end of pregnancy (pre-eclampsia)

``` ***FYI*** S/S that are normal during pregnancy that mimic heart dz Clinically? Sx? Auscultation? ```

Clinical Signs: Peripheral edema, JVD Sx: Reduced exercise tolerance, Dyspnea Auscultation: S3 gallop, Systolic ejection murmur **others noted in previous cards

``` During pregnancy, increase or decrease? CO ____ MAP ____ SVR _____ PVR ____ HR ______ ```

``` CO + (43%) MAP - (10%) SVR - (21%) PVR - (34%) HR + (17%) ```

There is a __-___% increase in SVR during labor

10-25%

“____” is 300-500cc can occur during labor because of the decrease in vascular resistance What do you worry about in pts w/ heart dz?

Autotransfusion - from blood being squeezed into central circulation during contractions cardiac overload

What happens to CO as labor progresses?

It increases

The uterine position extends to the ___ at 12 weeks

Pelvis

The uterine position extends to the ____ at 20 weeks

Umbilicus

What can the enlarging uterus cause in the: Bladder ____ Ureter ____ SI joint and Pubic symphysis ____

Bladder– frequency Ureter– hydroureter SI joint, Pubic symphysis– pain

Progesterone stimulates ____, which is also made by the placenta

Renin

What is the result of increased renin production?

Increased absorption of Na+ Increased excretion of K+ Water retention: 6-8 liters

What is the result of the increase of blood volume during pregnancy on renal workload? What happens to GFR? What can these changes lead to?

50-75% increase in renal workload GFR: 50% increase Dilution of plasma proteins like albumin = lower colloid oncotic pressure - leads to peripheral edema

What are the urinary tract changes that occur during pregnancy?

Ureteral dilation / hydroureter Dilation of renal pelvices and calyces Increased kidney size

Ureteral dilation is caused by: 1. _____ causes smooth muscle relaxation– including the peristaltic muscles of the ureter. 2. Later, uterine obstruction exacerbates the slowdown- especially on the (right/left) 3. Urinary stasis increases ____ and risk of ____ that can ascend more easily.

1. Progesterone 2. Right 3. ureteral dilation; bladder infection

Due to the ureteral changes, ____ is much more common in pregnancy

pyelonephritis

T/F: In general, respiratory rate and IRV (inspiratory reserve volume) do not change during pregnancy.

What are respiratory adaptations that occur during pregnancy?

1 . Thorax (2 cm diameter, 5-7 circumference increase) 2. Tidal Volume increases 30-40% 3. FRC is reduced by ~20% because of smaller lung size at the end of respiration - less inspiration reserve volume - larger tidal volume - smaller residual volume

During pregnancy the _____ increases by 2cm, and the ____ increases by 5-7cm

transverse diameter | circumference

What are the pH changes due to respiratory adaptations in pregnancy?

- More CO2 is exhaled/minute - pH rises slightly (7.44+) - ↑PaO2; ↓PaCO2 (40 – 30)

What are GI changes that occur during pregnancy?

- Slowed GI motility - Relaxation of LES (GERD) - Nausea / vomiting - Liver / gallbladder (stasis, stones) - ↑ liver production of coagulations factors (clotting tendencies) - ↑ binding proteins

N/V in pregnancy are often proportional to ___ levels. When is Hyperemesis gravidarum (HEG) worst/most common? (in weeks, why?)

HCG weeks 9-12 (when hCG is highest)

Other than hCG, what else may contribute to N/V of pregnancy?

Estriol | Leptin

____ can mimic TSH, which increases T3/T4 and can also contribute to N

HCG

How can you tx Hyperemesis gravidarum (HEG)?

``` 1st: conservative tx IV hydration Phenegran, zofran GI motility durgs (reglan) Unisom _ B6 ```

If a woman presents w/ Hyperemesis gravidarum (HEG), what may you want to check for?

``` Multiple gestation (HCG can be higher) Thyroid assessment to r/o Graves ```

What are some orthopedic adaptations that occur during pregnancy?

Altered center of gravity Altered gait Joint laxity

What are some skin changes that can occur during pregnancy? (x6)

- Spider angiomata and palmar erythema - Hair growth (abdomen and face) - Mucosal hyperemia - Striae gravidarum - Hyperpigmentation - Rashes and acne relatively common

What endocrine changes occur in the pancreas?

Carbohydrate metabolism Insulin resistance Human placental lactogen, cortisol

What endocrine changes occur due to thyroid function?

Increased TIBG (via liver) Increased total T4 and T3 - free levels unchanged - HCG suppresses TSH

What endocrine changes occur due to adrenal function?

Free plasma cortisol is elevated | - CRH from placenta stimulates ACTH

Maternal glucose can cross the placenta to the baby, but insulin cannot. So how does this baby metabolize the glucose?

They make their own insulin

Where will the baby store glucose? In what form is the glucose stored?

Stored as glycogen in the: - trunk - shoulders - liver

Diabetic mothers are at high risk of what complication during delivery?

Shoulder dystocia | ***requires C-section

Fetal wt = lbs 4000 g = ___ lbs 4500 g = ___ lbs 5000 g = ___ lbs

4000 g = roughly 9 lbs 4500 g = roughly 10 lbs 5000 g = roughly 11 lbs

What are fetal complications that occur due to maternal diabetes?

Macrosomia Hyperbilirubinemia Birth injury from shoulder dystocia

Who should be screened for Gestational DM? | When should this screen occur?

ALL pregnant pts | 24-28 weeks

Early gestational DM screening is required for who? If early screen is normal, then when should it be repeated?

Pts w/ RF - prior GDM - impaired glucose metabolism - BMI > 30 Repeat at 24-28 weeks

How is the GDM screening performed?

Check glucose after 50g sugar load

If GDM screening is abnormal, what should you do?

Perform 3 hr GTT w/ a 100g sugar load or FBS and 2 hour glucose test **if FBS is elevated, criteria for GDM is met

What happens to the immune system during pregnancy?

It is turned DOWN * *autoimmune dzs are alleviated during the pregnancy :) * *make sure immunizations are UTD

What are pregnant women more susceptible to?

CMV HSV Varicella Malaria

What is the TORCH titer?

``` T = Toxoplasmosis, Hepatitis B, Syphilis, Varicella O = Other R = Rubella, Rubeola C = CMV H = Herpes simplex ```

What is the worry w/ TORCH infections? When are these infections the most detrimental?

birth defects stillbirth worse in 1st trimester

____ is transmitted to the mother through raw meat or exposure to infected cat’s feces

Toxoplasmosis rare; toxoplasma gondii [protozoal infection] Severity > in 1st trimeter

_____ is a member of herpesvirus, worse in 1st trimester, infant may have life-threatening dz

Varicella

____ has a 50% rate of malformation in the 1st trimester such as: Hearing loss, Deafness, Blindness, Heart/Neuro defects, Mental Retardation

Rubella

___ is part of herpesvirus family. Fetal Defects: mental retardation, hydrocephaly , microcephaly, blindness, deafness. If 1st trimester infection occurs, may consider AB.

Cytomeglovirus

___ can cause blindness, MR, death if primary case happens during pregnancy

HSV 1 or 2 [genital ]

Perinatal HSV can cause ____ if contracted in birth canal during delivery **Check for lesions prior to delivery

HSV encephalopathy

``` WHAT IS THE RISK to the infant? Varicella ____ CMV____ HIV ____ Parvovirus B 19 ____ Syphilis- risk ____ Group B strep ____ ```

Varicella: risk = neonatal/ perinatal encephalopathy and/or maternal pneumonia CMV: risk = retinitis HIV: risk = perinatal transmission Parvovirus B 19: risk = fetal hydrops Syphilis: risk = PTL, PTD, IUGR, perinatal transmission, fetal hydrops/ HSM, and more Group B strep: risk = GBS pneumonia, sepsis

What can cross the placenta to the baby? To the mother?

To the baby: O2, water, electrolytes, nutrients, hormones, antibodies, drugs, viruses To the mother: CO2, water and urea, waste products, hormones