Reproduction II: Pregnancy Flashcards
1
Q
It takes ____ days for the embryo to travel through the tube to the uterus, then it takes about ____ days to implant into the uterus.
A
It takes three days for the embryo to travel through the tube to the uterus, then it takes about 3 more days to implant into the uterus.
2
Q
The earliest hCG is detectable in circulation about ___ days after conception.
The earliest hCG is detectable on a serum pregnancy test is about ___ days after conception.
The earliest hCG is detectable on a urine pregnancy test is about ___ days after conception.
A
The earliest hCG is detectable in circulation about eight days after conception.
The earliest hCG is detectable on a serum pregnancy test is about fourteen days after conception.
The earliest hCG is detectable on a urine pregnancy test is about twenty eight days after conception.
3
Q
Blastocyst structure
A
4
Q
Pre-implantation development of a fertilized egg
A
5
Q
The trophoblast becomes. . .
A
. . . the placenta and membranes.
6
Q
By convention, obstetricians date pregnancies from. . .
A
. . . the first day of the last menstrual period (LMP) rather than from conception, with day one of the cycle assigned to the first day of the menses.
7
Q
Naegele’s Rule for estimating due date
A
EDD (in the following year) = LMP - 3 months + 7 days
8
Q
hCG bears substantial structural resemblance to ___, which causes receptor cross-reactivity.
A
hCG bears substantial structural resemblance to LH and TSH, which causes receptor cross-reactivity.
9
Q
Pregnancy tests employ an antibody that is specific to. . .
A
. . . just the beta subunit of hCG
This ensures that they do not cross-react with the alpha subunit in FSH, LH, or TSH.
10
Q
How a home pregnancy test works
A
11
Q
The first prenatal visit for a pregnancy should occur at . . .
A
. . . 8 weeks gestation (ideally before 12 weeks)
12
Q
All women planning to become pregnant receive a ___ supplement.
A
All women planning to become pregnant receive a 0.4 mg daily folate supplement.
This reduces the risk of neural tube defects in early pregnancy,
13
Q
Laboratory studies collected at first prenatal visit
A
- Blood and Rh typing,
- antibody screening,
- hepatitis and rubella titers,
- HIV and syphilis screening,
- HbsAg,
- HCV,
- chlamydia and gonorrhea screening
14
Q
When does the placenta take over as a producer of progesterone?
A
At ~10 weeks (end of the first trimester)
15
Q
Endocrine changes during pregnancy
A
- Increased T3/T4 and TBG (net neutral)
- Increased insulin secretion
- Increased cortisol binding globulin levels (via estrogen), net neutral
16
Q
Nausea and vomiting in pregnancy are principally due to . . .
A
. . . progesterone and hCG elevations.
These symptoms resolve by 14 weeks for most women.
17
Q
Gastric reflux and constipation in pregnancy
A
- Common
- Gastrointestinal motility and gastric emptying are reduced due to increased levels of progesterone
- This is magnified by mass effect of uterus in 2nd and 3rd trimesters
- Prolonged GI transit time results in more water resorption, leading to constipation
- Gastric reflux is caused by progesterone-mediated decrease of lower esophageal sphincter tone.
- Iron given to pergnant women to ensure adequate red cell mass also causes constipation
18
Q
Fetal iron
A
If iron is not readily available, the fetus uses iron from maternal stores
Thus, the production of fetal hemoglobin is usually adequate even if the mother is iron deficient
19
Q
Gall stones in pregnancy
A
Gallbladder motility is also slowed by progesterone, resulting in increased biliary cholesterol saturation and increased risk of gallstones.
20
Q
Circulating volume in pregnancy
A
- Progresses throughout pregnancy, increasing by 45-50% and peaking at 32 weeks (third trimester).
- Needed for the additional blood flow to the uterus, metabolic needs of fetus, and increased perfusion of other organs, especially kidneys
21
Q
Cardiac output in pregnancy
A
During pregnancy, cardiac output rises gradually and reaches its peak around 20-24 weeks
Primarily due to increased stroke volume and, to a lesser extent, increases in heart rate
22
Q
How does intravascular volume increase during pregnancy?
A
- Progesterone acts as a vasodilator
- Blood pressure declines and the RAAS is activated
- Sodium and water retention
23
Q
Heart rate increases ~___ during pregnancy
A
Heart rate increases ~15-20 beats per minute during pregnancy
24
Q
Summary of cardiovascular changes in pregnancy
A
- Maternal total body water ↑ 6-8 liters
- Fetus, placenta, amniotic fluid ↑ 3.5 liters
- Total blood volume ↑ 50%
- Red cell mass ↑ 35%
- Blood pressure ↓ 6-10 mm Hg
- Heart Rate ↑ 12-18 beats/min
- Stroke volume ↑ 10-30%
- Cardiac Output ↑ 33-45%
25
Supine hypotensive syndrome
Third trimester, pregnant patients are prone to experiencing postural hypotension when lying supine, where the **enlarged uterus can compress the IVC thus reducing preload**, resulting in presyncopal symptoms.
This problem can be **alleviated by putting the patient in left lateral decubitus position** to displace the uterus from compressing the IVC.
26
Dyspnea during early pregnancy is thought to be. . .
. . . a central **(“controller”) effect** caused by **progesterone** (which is a respiratory stimulant)
27
Chest wall changes of pregnancy
* **Relaxation of the ligaments** between the ribs and sternum, due to the softening effect from the hormone **relaxin (produced by the placenta)**
* **Subcostal angle increases** from 70 to 100 degrees
* **Chest circumference expands** by 5-7 cm
28
Pulmonary changes in pregnancy (PFT values)
* Total lung capacity increases by 5%
* **Tidal volume increases by 40%**
* **Minute ventilation increases by 40%**
* **Respiratory rate unchanged**
29
Normal blood gases for non-pregnant vs pregnant women
Note that the hyperventilation caused by pregnancy is compensated for by renal HCO32- excretion
Thus, pregnancy is a state of compensated chronic repiratory alkalosis
30
Clotting factors in pregnancy
* **Mostly due to hepatic actions of estrogen**
* Fibrinogen and Factor VIII levels increase substantially
* Fibrinolysis is suppressed, though plasminogen levels also increase
* Protein S and Protein C levels decrease
* Summary: **Pregnancy is a net pro-coagulative state**
31
Virchow's triad in pregnancy
* All three components are there normally!
* AND high estrogen predisposes to clotting
* **Risk is even higher in post-partum period**
32
White cells in pregnancy
* Normal in first trimester
* During the second and third trimester, the range is 5,000-12,000
* In labor, it may rise to 20,000-30,000
* **Almost all of this variability is due to neutrophils**
33
Immunological changes in pregnancy
* Large rise in circulating neutrophils
* Modulation away from cellmediated immune responses toward antibody-mediated immunity
* Th1 \< Th2 (thus, **increased susceptibility to intracellular pathogens**. Also why people with Th1-mediated disorders, like RA, improve during pregnancy)
* Increased Tregs
34
Kidney function in pregnancy
* More intravascular volume means more blood to be filtered
* **GFR increases by ~50%** (thus, decrease in BUN and creatinine)
* Baseline (non-pathological) **proteinuria level increases** a bit as well
* Upper normal for pregnant women is 200 mg/day
* May yield "positive" dipstick test, just know that this is not a big deal
* Minor glycosuria as well
* **RAAS is almost constitutively active -- this is important for pregnancy and why RAAS blockers are contraindicated**
35
Sample pregnant labs
36
Breast tissue changes in early pregnancy
* Breast tenderness and tingling
* Increase in breast size and apperance of subdermal veins
* Nipples and areolae become larger, more pigmented, and more erectile
* Colostrum may be expressed from nipple mechanically
* Glands of Montgomery become prominent
37
Colostrum
Thick, yellowish fluid produced by breasts early in developmental changes that are part of pregnancy.
Also the first milk secreted by breasts after pregnancy. Contains more minerals and protein, but less sugar and fat. Also contains IgA. Persists for about 5 days post-delivery, then is replaced by more mature milk.
38
What ultimately stimulates milk production in a women following delivery?
The disinhibition of prolactin by the fall in estrogen levels after delivery.
Also, prolactin and oxytocin stimulated by suckling.
39
The only vitamin not found in human milk
Vitamin K
This is why all babies get Vitamin K supplementation as part of the post-delivery workup!
40
Oxytocin in milk secretion
Causes the contraciton of myoepithelial cells in the alveoli and milk ducts, pushing stored milk through the ducts and out of the nipple.
41
Monozygotic twins result when. . .
. . . a fertilized ovum divides after conception
42
Types of monozygotic twin pregnancy chorionicity
Depending upon the timing of the fertilized ovum split, the resulting chorionicity can be **diamniotic dichorionic** (early), or **diamniotic monochorionic**, or **monamniotic monchorionic**, or **conjoined twins**
43
Dizygotic twins are always \_\_\_
Dizygotic twins are always **diamniotic dichorionic**
44
Mechanism of gestational diabetes
* Insulin resistance, mediated by placental secretion of diabetogenic hormones
* Resistance increases as pregnancy progresses
* Human placental lactogen (hPL) is the major culprit
* Diverts maternal carbohydrate metabolism to fat metabolism in the third trimester
* Net effect is to **favor placental transfer of glucose to the fetus** and to **reduce the maternal use of glucose**
* hPL steadily rises through 1st and 2nd trimesters, plateauing in the 3rd
45
Adverse outcomes associated with diabetes during pregnancy
* Preeclampsia
* Macrosomia and large for gestational age infant
* Maternal and infant birth trauma
* Operative delivery
* Perinatal mortality
* Neonatal respiratory problems and metabolic complications (hypoglycemia, hyperbilirubinemia, hypocalcemia)
46
Hypertensive disorders in pregnancy
47
Screening for gestational diabetes
* Recommended at 24-28 weeks gestation with glucose tolerance testing
* If a **one-hour 50 gram glucose loading test** is abnormal, a **three-hour 100 gram oral glucose tolerance test** is performed with time-dependent glucose cut-offs to determine likelihood of gestational diabetes
48
Normal placental vasculature development
In normal pregnancy, maternal **uterine spiral arteries** of placenta endothelium are **replaced and lined with fetal-derived cytotrophoblasts**, which then become high capacitance and low resistance to ensure adequate delivery of maternal blood to the placenta
49
Cause of preeclampsia
Vasculogenic and angiogenic signaling pathways are abnormal, resulting in abnormal trophophoblast invasion and development of lower capacitance, higher resistance spiral arteries than a typical pregnancy.
The end result is systemic vasoconstriction and systemic endothelial dysfunction.
50
Risk factors for preeclampsia
First pregnancy (**primiparity**), **multiple gestation**, a **prior history** of preeclampsia, **chronic hypertension**, **chronic renal disease, history of thrombophilia, systemic lupus erythematosus,** **in vitro fertilization, advanced maternal age (\>35)**, **pregestational diabetes, obesity, and family history** are all risk factors for developing preeclampsia
51
Diagnosing preeclampsia
52
Eclampsia
Life-threatening for both the mother and the fetus.
**Eclamptic seizures** are typically **self-limited**, thus **_magnesium sulfate should be administered as soon as possible_** to prevent further seizures.
After a seizure, there are often fetal heart rate changes **(bradycardia) that tend to resolve within 15 minutes**; delivery during this immediate postictal timeframe should be avoided.
53
In the United States, ___ of pregnancies are unplanned, and ___ of these pregnancies end in termination (abortion)
In the United States, **50%** of pregnancies are unplanned, and **43%** of these pregnancies end in termination (abortion)
54
MA abortion legislation
In Massachusetts, abortion is allowed before 24 weeks, unless it is to save the life of the mother. Minors (under 18) must have parental consent.
Within Massachusetts, a physician must provide surgical abortion, but advanced care clinicians can provide medical abortion
55
Pharmacologic abortion
Mixture of mifepristone (terminates pregnancy) and misoprostol (aids in expulsion)
Approximately 5% of medical abortion cases eventually require a surgical aspiration due to retained pregnancy tissue.
56
Surgical abortion
A surgical abortion includes a dilation of the cervix followed suction aspiration of the pregnancy tissue. Surgical abortion is very safe, with 0.5% risk of major complications (infection, bleeding, damage to uterus).
57
"Three delays model"
* Delay in the decision to seek care (e.g., unrecognized life-threatening illness, women needing to seek permission from family members before obtaining care)
* Delay in arrival to an appropriate medical care facility (e.g., poor or no transportation, long distance from care facility)
* Delay in receiving adequate care once a woman arrives to medical facility (e.g., unrecognized or under-treated life-threatening condition, inadequate facilities for severity of disease).
58
Maternal death
The death of a woman while pregnant or within 42 days of the end of the pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes
59
Direct obstetric death
A direct obstetric death results from obstetric complications of pregnancy, from interventions, omissions, incorrect treatment, or from chain of events resulting from pregnancy, labor, delivery, or postpartum conditions.
60
Indirect obstetric death
An indirect obstetric death results from preexisting disease (e.g., diabetes, cardiac disease, malaria, tuberculosis, HIV)
61
\_\_\_ are often utilized to reduce the risk of embolism in women in the peri-partum period, espetially immediately after delivery.
**Pneumatic compression devices** are often utilized to reduce the risk of embolism in women in the peri-partum period, espetially immediately after delivery.
Patients who are especially high risk are given LMW heparin
62
Trimesters of pregnancy
63
Twin-twin transfusion syndrome
Occurs **only** in monozygotic/monochorionic/monoamnionic twins.
Vascular anastamoses form within the placenta between the developing vascular supplies of the twins: specifically, the **artery** of one twin **(the donor twin)** attaches to the **vein** of the other twin **(the recipient twin)**. This creates a **unidirectional shunt.**
The result is that **one twin (the recipient) gets circulatory overload (hydrops) and polycythemia,** while the **other twin (the donor) is anemic, growth restricted, and oliguric.**
64
Pathophysiologic progression of preeclampsia
65
Magnesium toxicity
66
Leading causes of death for pre-term infants
* Respiratory distress
* Infection
* Intraventricular hemorrhage
67
Prophylaxis for premature infants
68
Tocolytics
Medications used to suppress premature labor **in an acute setting.**
These are not something a woman would take all throughout the first trimester until their expected date. Rather, they are for stopping premature labor for long enough for an individual to become stabilized or have glucocorticoids administered in order to ensure adequate neonatal surfactant production (~1-2 days).
69
Common tocolytics and contraindications
70
How to mitigate the risk of pre-term delivery in an at-risk patient
Progesterone therapy may be used for this purpose in the **chronic** setting, as opposed to tocolytics which are for **acute** suppression.
Excess progesterone causes inhibition of cervical ripening, reduction of myometrial contractility, and modulation of inflammation -- all of which help prevent pre-term births in at-risk individuals.
The major at-risk populations are those w/ history of prior pre-term delivery and those with an anatomically short cervix.
71
Development of Sheehan syndrome
72
Side effect of levanogestrel
Levanogestrel acts as a progestin, but also has some cross-reactivity with androgen receptors.
For this reason, it should be avoided in combined contraceptive pills in individuals with PCOS. Other progestins with less overlap are better treatments.
