(IV) Prescribing During Pregnancy // Normal and Abnormal Labor and Delivery

what are some common changes in maternal physiology during pregnancy

- increased CP

- plasma volume expands

- decreased in GI motility

- decreased serum albumin

how does increased plasma volume in pregnant women affect medication?

decrease concentrations of medications

how does body fat affect medications in pregnant women?

increased body fat can absorb lipophilic meds and further after distribution

why does GFR increased in pregnancy?

renal blood flow increases

an increase in GFR affects medications how?

- leads to reduced concentration of meds that are cleared through kidneys

- decreased the half life

decreased albumin means what to the drug?

decreased protein binding and increases free drug

free drugs are able to move into target tissue which ___________ concentrations compared to nonpregnant patient given the same dose

increase

decreased protein binding can also affect elimination bc ___________

only free/unbound drug can be metabolized/renally cleared

what are the Gastrointestinal changes in pregnant pt while taking medications

- Progesterone affects GI motility which can delay gastric emptying and increase intestinal transit time

- Can increase drug absorption

what are the Change in drug metabolizing enzymes in pregnant pt while taking medications

- Can increase or decrease in activity

- Affects Phase I and Phase II of metabolism which can alter concentrations and efficacy

The Placenta acts as a barrier but also involved in the ___________ of substances

transportation

Placenta contains multiple drug _____________ that help move substances towards or away from the fetus

- Present on both maternal-facing side and fetal-facing side

influx/efflux transporters

Activity of the placenta can result in what type of distribution?

unequal distribution of drugs between the patient and fetus

*Transporter expression can vary with gestational age or remain constant throughout pregnancy

Factors affecting placental drug transfer:

- Lipid solubility (diffuse readily across)

- Molecular size and pH (lower weight, pH >7.4 cross easy to fetus)

- Placental drug metabolism (metabolize some medications on its own)

____________ the FDA came out with pregnancy risk categories to apply to medications– Focused on the risk to the fetus

1979

pregnancy categories 2015 Pregnancy and Lactation Labeling Rule (PLLR) in 3 sections:

pregnancy

lactation

F/M reproductive (NEW)

* only applies to Rx, not OTC

PLLR labeling is required to include what 3 parts?

- Summary of the risks of using the drug

- A discussion of the data that supports the summary

- Information to help healthcare providers counsel their patients and make informed prescribing decisions

Factors that can cause abnormalities in the form or function of a developing fetus

Teratogens

what are some teratogen examples

- Drugs

- Environmental exposures (heat, radiation, mercury)

- Maternal medical disorders

- Infectious agents

what do teratogenic effect depend on?

dosing and when the drug is administered during fetal development

1st trimester is a crucial period of ___________ and is particularly susceptible to what?

organogenesis

significant structural malformations

2nd/3rd trimester are more likely to cause what?

growth/functional defect

marketed as a treatment for morning sickness in pregnant women--> Resulted in thousands of babies that were born with severe deformities

thalidomide tragedy

why avoid all 1st gen Carbamazepine antiseizure drugs in pregnancy?

neural tube defects, heart malformations

why avoid all Phenytoin antiseizure drugs in pregnancy?

growth delay, CNS defects

why avoid 1st gen Topiramate antiseizure drugs in pregnancy?

growth delay, cleft lip and cleft palate

why avoid all Valproic acid antiseizure drugs in pregnancy?

neural tube defects, craniofacial defects, heart malformations

what sex hormones do you avoid in a pregnant pt? why?

- Androgens (2nd/3rd) - masculinization of female fetus

- Estrogens - congenital defects of female reproductive organs

why avoid all Tetracycline antimicrobial drugs in pregnancy?

teeth and bone staining

why avoid TMP-SMX (bactrim) in a pregnant pt?

neural tube defects, CV malformations, cleft palate, GU abnormalities

why avoid macrolides in a pregnant pt?

CV and genital malformations

why avoid Fluoroquinolones in a pregnant pt?

cartilage and bone defects in animal models

why avoid Methotrexate Anticancer drugs in a pregnant pt?

CNS and limb malformations

what avoid all ACE/ARBs in a pregnant pt?

renal tube dysgenesis, pulmonary hypoplasia, skull hypoplasia

what avoid all Methimazole, antithyroid, drugs in a pregnant pt?

tracheoesophageal fistulas, aplasia cutis

why avoid Retinoids (isotretinoin - all)?

CNS and cardiac defects, ear/cleft defects

why avoid antidepressants (SSRIs/SNRIs - 3rd) in a pregnant pt?

heart disease, pulmonary hypertension

Lithium causes what abnormality of the heart?

Ebstein abnormality

why avoid all NSAIDs (but mostly 3 rd gen)

- premature closure of the ductus arteriosus, renal dysfunction

why avoid warfarin

nasal hypoplasia, CNS malformations

why avoid statins

potential for fetal harm such as limb malformations, congenital heart disease, and CNS abnormalities

do med pass into breast milk in small or large amounts

small

best time for mother to take meds

take medications immediately after breastfeeding or before baby's longest period of sleep

Drugs that do NOT pass into breastmilk

- Epinephrine

- Heparin

- Insulin

Drugs that can suppress milk production

- Estrogen

- COCs that contain high

-dose estrogen

- Trazodone

- Levodopa

Emerging area of perinatal pharmacology

Involves drug administration to the pregnant female but with the fetus as the target of the drug

Fetal Therapeutics

Fetal Therapeutics example

- Corticosteroids to stimulate fetal lung maturation when preterm

- Antiarrhythmics for treatment of fetal cardiac arrhythmias

- HIV medications to eliminate fetal infection

Braxton-Hicks contractions are characterized by what

Irregular, generally painless contraction

in 3rd trimester

how do you tell the difference between Braxton-Hicks contractions and labor contractions?

NO dilation of cervix - "false labor"

Can be relieved with ambulation and hydration

what is lighting? when does it happen?

Lighter sensation from fetal head descending further into pelvis

Baby “drops” – typically in last 2-4 weeks of pregnancy

leading up to labor, mucus forms in cervical canal during pregnancy acts as a _____________.

Cervix softens and thins in days/weeks prior to labor - mucus plug passes and may present as what?

barrier against infection

blood-tinged musus - "bloody show"

First stage of labor. how is it divided?

Interval between onset of labor and complete cervical dilatation

Further divided into “latent/early” and “active” phases

Second stage of labor

Interval between complete cervical dilatation and deliver of baby

Third stage of labor

Interval between delivery of baby and delivery of baby and delivery of the placenta

The Three P's of Successful Labor and Delivery

power (Force generated by uterine contractions)

passenger (Characteristics of the fetus including size, weight, lie, presentation, and position)

passage (The bony pelvic and soft tissue of the birth canal. Different pelvic types can make delivery easier or more challenging)

Relation of fetal long axis to the maternal long axis Longitudinal in most cases

Lie (passenger)

Part of the fetus that presents itself lowest in the birth canal

Most common cephalic – can also be breech/transverse

Presentation (passenger)

Fetal presenting part either to the right or left side of the pelvis

Position

the cervix needs to get to ________ cm to delivery

10 cm

Thinning and shortening of the cervix

Effacement

Effacement must be ____________% effaced for delivery

100%

Position of baby's head in relation to the ischial spines (in cm) From -5 to +5

station

in station, with 0 being means baby's head is where?

at the spine

Latent/early phase (stage 1) of labor is what?

Onset of labor

What is the latent/early phase of labor?

It is the first stage of labor.

describe contractions during the latent phase of labor?

Contractions are more mild and less frequent - can be irregular.

What happens to the cervix during the latent phase of labor?

The cervix gradually softens, opens, and gets thinner.

How long does the latent phase of labor typically last?

It is the longest stage of labor and typically lasts several hours.

Where do most patients complete the latent phase of labor?

at home.

What begins the active phase of labor?

When the cervix is dilated about 6 cm.

How long does the active phase of labor typically last?

On average 3-5 hours.

characteristics of contractions during the active phase?

more frequent, painful, and regular.

Typically should go to the hospital when contractions are ________ minutes apart for > 1 hour AND ____________

3-5

last longer than 45-60 seconds each

what do PAs do when pts get to the hospital?

- Review prenatal records - confirm gestational age - Determine whether new issues have developed since last prenatal visit

- Check patient's vital signs Check fetal heart rate (FHR) and assess frequency, qualify, and duration of contractions

- Perform exam to determine fetal lie, presentation, and position

when do you perform digital vaginal exam

AFTER placenta previa and prelabor rupture of membranes excluded

placenta extends over the internal cervical os (it's in the way) Evident on US, can cause bleeding

Placenta previa

Patient may report leaking/gushing of fluid, can increase infection risk if contractions haven't begun

"my water broke"

Rupture of membranes

confirm what on a digital vaginal exam?

confirm cervical dilation/effacement and fetal station

when to ambit a pt to the labor unit

Patients who are transitioning to active labor

Key criteria to look for during active labor (3)

- Regular contractions that require patient's focus and attention

- Significant cervical effacement (> 80%)

- Cervical dilation between 4-6 cm

steps to admission

Labs

restrict OP

IV access

Perform vaginal exams at 2-4 hour intervals OR prior to analgesia OR with FHR abnormalities

what labs do you get on admission

Baseline labs - CBC, type & screen, STI if high risk, GBS if not previously performed

what do you restrict on admission?

PO intake - clear liquids usually okay if low risk of needing C-section

what do you give In GBS + patients?

IV penicillin G (initial dose then q 4 hours until delivery)

what to five fro GBS+ pt with a PCN allergy?

clindamycin or vancomycin

First stage of labor Pain is all ___________ and is from where?

visceral

from uterine contractions and cervical dilation

Second stage of labor pain is_________ and is from where?

visceral and somatic

from contractions as well as vaginal and perineal tissue distention More severe than the first stage

Nonpharmoptions pain management options

Does not cause resolution of pain but allows patient to better cope with pain

- Massage Movement

- Applying heat or col

- Breathing techniques

- Taking a shower

- TENS unit Aromatherapy

Pham pain management options

Opioids

Nitrous oxide

Neuraxial analgesia

What is an example of an ultra short-acting opioid?

Remifentanil

What is a common side effect of opioids?

Nausea and vomiting (N/V) or drowsiness

Do opioids cross the placenta?

Yes

What effect can opioids have on fetal heart rate (FHR)?

They can decrease FHR

when do avoid opioids

if birth is imminent

Nitrous oxide "laughing gas" risk

respiratory depression, so monitor for resp. depress.

Most effective pain management option

Epidural or spinal neuraxial analgesia

when to administer Neuraxial Analgesia? what is the most common technique

Can usually be initiated at any point during labor

Epidural and combined spinal-epidural (CSE) are most commonly used techniques

should be considered in those at high-risk for C-section in order to avoid general anesthesia

Neuraxial Analgesia

Potential side effect of Neuraxial Analgesia

- hypotension, pruritus, fever

contraindication with Neuraxial Analgesia

coagulopathy, thrombocytopenia, infection of lower back, and increased intracranial pressure