Pregnancy Flashcards
1st trimester length
Week 1- end of week 13
2nd trimester length
Week 14- end of week 26
3rd trimester length
Week 27 until birth
What is day 1 of pregnancy?
First day of menses (still counts as day 1 even though conception hasn’t taken place yet!)
Risk of harming the fetus at weeks 3 and 4
All or none effect; fetus may be fine or die via spontaneous abortion
Risk of harming the fetus at weeks 5-10
Major congenital anomalies likely
Risk of harming the fetus at weeks 11-birth
Functional defects and minor anomalies possible
What can harm the fetus? (Causes for birth defects and the like)
“Naturally occurring” congenital anomalies, other causes like genetics/chromosomal, environmental, unknown causes, medication-induced
Teratogens definition
Exposure to an agent that causes malformation of an embryo
Teratogenic medications during weeks 5-11 that can result in structural abnormalities
Methotrexate, cyclophosphamide, diethylstilbestrol, lithium, retinoids, thalidomide, anti-epileptic drugs (AEDs), Coumadin/warfarin
Teratogenic medications after 11 weeks that may result in growth retardation, CNS, or other abnormalities or death
NSAIDs, TTC ABX
3 mechanisms on how medications can harm the fetus
- Act directly on the fetus to cause damage, abnormal development, or death
- Alter the function of the placenta by causing blood vessels to construct and reduce the supply of oxygen and nutrients to the fetus
- Cause the muscle of the uterus to contract forcefully, indirectly injuring the fetus by reducing its blood supply or triggering preterm labor and delivery
When estimating risk for whether or not a medication can be used in a pregnant patient, what do you have to consider and take into effect?
Consider the quality of evidence; use safety data from randomized, controlled trials if possible
Principles for drug use during pregnancy
- selecting drugs that have been used safely for a long time
- prescribing doses at the lower end of the dosing range
- elimination nonessential medications and discouraging self-medication
4, avoiding medications known to be harmful (teratogens)
How do most drugs move from the maternal to fetal circulation?
Diffusion through the placenta
Functions of the placenta
Transfers oxygen and nutrients from mother to fetus and permits release for CO2 and waste from the fetus
Effect of lipophilicity on medication diffusion across the placenta
More lipophilic, will cross more readily
Effect of molecular weight on medication diffusion across the placenta
MW <5000Da readily crosses the placenta
Effect of protein binding on medication diffusion across the placenta
Unbound (low protein binding) drugs cross more easily but highly protein-bound drugs will cross more easily as pregnancy progresses
Effect of pH on medication diffusion across the placenta
Weak bases cross more easily
Maternal plasma volume, cardiac output, and GFR increase by ≥30-50% on medication use
Lowers concentration of renally cleared medications
Maternal increase in body fat on medication use
Increased Vd of fat-soluble medications
Maternal decrease in plasma albumin concentration on medication use
Increased Vd of highly protein-bound medications; unbound drugs cleared more rapidly by the liver and kidney so little effect on concentration
Maternal hepatic perfusion increase on medication use
Increased hepatic extraction of drugs
Maternal N/V on medication use
Altered absorption
Maternal delayed gastric emptying on medication use
Altered absorption
Maternal increase in gastric pH on medication use
Absorption of weak acids and bases affected
Maternal increase in estrogen and progesterone levels on medication use
Altered liver enzymatic activity (either increases or decreases removal)
Maternal factors that go into determining appropriate medication use
Will the medication harm her?
Will the medication need dosing or frequency changes due to maternal PK/PD?
How will an untreated disease impact the health of the mother and fetus?
Fetal factors that go into determining appropriate medication use
Is the medication teratogenic or able to cause fetal adverse outcomes?
Which trimester and how many weeks gestation is the infant?
How will an untreated disease impact the mother and fetus?
Nonpharm treatment for constipation
physical activity and increasing/supplementing fiber
Pharm treatment for constipation
stool softener (Docusate) –> osmotic laxatives (lactulose, sorbitol, PEG) –> stimulant laxatives (Senna or bisacodyl)
Which medications do you not use for constipation in pregnancy?
Castor oil and mineral oil
Nonpharm treatment for hemorrhoids
Dietary fiber, increased fluid intake, sitz baths
Pharm treatment for hemorrhoids
laxatives, stool softeners, topical anesthetics, hydrocortisone
Nonpharm treatment for GERD
small, frequent meals, no food before bed, avoid alcohol/tobacco/food triggers
Pharm treatment for GERD
TUMS, cimetidine, omeprazole OTC (reserved for if/when cimetidine fails)
Which medications do you not use for GERD in pregnancy?
Sodium bicarbonate, Mg trisilicate
Nonpharm treatment for N/V
Small, infrequent meals, bland meals
OTC pharm treatment for N/V
B2 or doxylamine, ginger
Rx pharm treatment for N/V
1st line: doxylamine and B6 (Diclegis)
2nd line: metoclopramide
3rd line: ondansetron (conflicting data though)
Nonpharm treatment for gestational DM
Dietary modification, exercise, checking BG QID
Pharm treatment for gestational DM
Insulin
BP level for HTN in pregnancy
> 140/90
Chronic HTN definition
HTN prior to pregnancy or before 20 weeks gestation; pre-existing and doesn’t resolve post-pregnancy
Gestational HTN definition
HTN with no proteinuria, developing after 20 weeks gestation
Preeclampsia definition
HTN with proteinuria
High-risk factors for preeclampsia
Preeclampsia in prior pregnancy, antiphospholipid syndrome, underlying medical conditions, chronic HTN, renal disease, DM
Moderate risk factors for preeclampsia
Multiple gestations, nulliparity, family Hx, obesity with BMI >35, maternal age >40, ethnicity
Preeclampsia signs and Sx
proteinuria, severe-persistent headache, persistent new epigastric pain, visual changes, vomiting, hyperreflexia, swelling of hands/face/feet, HELLP syndrome (hemolysis, elevated liver enzymes, low platelet count), increased SCr
Eclampsia definition
HTN with proteinuria AND SEIZURES
Eclampsia signs and Sx
cerebral irritation, severe and persistent headaches not relieved by medication therapy, new-onset blurred vision or vision changes (flashes of light), photophobia, hyperreflexia, altered mental status
Nonpharm treatment for HTN
activity restriction, stress reduction, exercise, calcium
Pharm Tx for HTN
Labetalol (1st line), nifedipine ER (1st line), methyldopa
Preeclampsia Tx
Same antihypertensives, ASA 81mg QD until delivery
Eclampsia Tx
Same antihypertensives, ASA 81mg QD until delivery, magnesium sulfate IV for seizure prevention
Only cure for preeclampsia and eclampsia
Placenta delivery
Treatment for hypothyroidism
Levothyroxine
Treatment for hyperthyroidism
MMI or PTU (1st trimester of pregnancy)
Treatment for thromboembolism
LMWH, continue for duration of pregnancy and 6 weeks postpartum
Treatment for UTIs
Beta-lactam ABX for 7-14 days (penicillin, cephalosporins) or nitrofurantoin
Can infants be infected with STIs in utero?
Yes
Nonpharm treatment for headache
relaxation, stress management, biofeedback
Pharm treatment for headache
APAP
Seizure management
Seizures may become more frequent because of changes in the mother, but the risk of uncontrolled seizures to the fetus are considered to be greater than those associated with the anti epileptic drugs
Depression management
Don’t use paroxetine; switch to a different antidepressant
Folic acid purpose
Prevention of NTD
Folic acid dosing for patients who aren’t taking AEDs
0.4-0.9mg QD
Folic acid dosing for patients taking AEDs and/or previously delivering a child with NTD
4mg QD
Smoking cessation for prenatal care
Cease tobacco use prior to conception, can try the gum, TD patch as long as they limit the time they wear to to 16 hrs/day, bupropion
Alcohol cessation for prenatal care
Stop consumption prior to conception
Illicit drug cessation
Stop before conception
Up-to-date vaccinations
…GET VACCINATED
AED management
use lowest possible AED dose to maintain control, folic acid 4mg QD, use effective pregnancy protection
Isotretinoin management
use effective pregnancy prevention, on REMS list
Warfarin management
Switch to LMWH prior to becoming pregnant, use effect pregnancy protection
Obesity management
Weight loss with appropriate nutritional intake before pregnancy