L17- maternal /fetal physiology and antepartum care

antepartum/prenatal

• entire preg from conception to start of labor

intrapartum

from onset of labor ro delivery of baby and placenta

postpartum

from childbirth to 6-8 weeks after birth (this timeframe can vary)

summary of prenatal care

• confirm dx of preg and determine gestational age

• monitor progress with periodic exams and screenign test

• assess well being of pt adn fetus

• provide education addressing preg and postpartum period

• preprare pt adn family for mgmt o flabor. delivery, and postpartum peroid

• detect medical and psychosocial complications

high risk pregnancy

• preg in which the mother, fetus, or newborn is at an increased risk of death or residual inury and thus requires additional resources, procedures, or specialized care to optimize outcome

1st trimester

• 0-13+6 weeks

2ns trimester

• 14-27 + 6 weeks

3rd trimester

• 28 weeks to delivery

early term

• 37 weeks through 38 weeks and 6 days

full term

• 39 weeks through 40 weeks and 6 days

late term

• 41 weeks through 41 weeks and 6 days

post term

• 42 weeks +

common early sx of pregnancy

• amenorrhea

• n/v

  • 50% of preg

  • as early as 2 weeks gestation until roughly 13-16 weeks for most

• breast tenderness

• fatigue

• increased urinary frequency

common early signs of pregnancy

• breast engorgement

• palpable uterus

  • just above pubic symphysis

  • approx 12 weeks

• chadwick sign

• heagar’s sign

chadwicks sign

• congestion of pelvic vasculature causes bluish discoloration of the vagina and cervix

• around 8-12 weeks gestation

hegar’s sign

• softening of uterine body and cervix

• around 6-8 weeks gestation

dx pregnancy- urine hCG

• home preg test or quick in office

• can detect hCG roughly 10 days after conception

• accuracy depends on user tech adn interp- risk of false pos/neg

dx pregnancy- serum hCG test

• dine in office

• more specific and sensitive

• hCG doubles apprix q1-2 days in first month of viable intrauterine preg

dx pregnancy- US

• gestational sac visible around 4-5weekd and yolk sac around 5 weeks

• cardiac activity discernible on transvaginal US at 6 weeks gestation

dx pregnancy- fetal heart tones (FHT)

• detectable by handheld doppler after 10 weeks gestation

• normal heart rate is 110-160bpm

determining gestational age

• gestational age and est datre of delivery (EDD) initially based on LMP ( if known)

• naegele’s rule

  • severeal limitation s including less accurate fro females with irregular menstrual cycles, who are unsure of LMP, or hwo conceive while breastfeeding and have lactational amenorrhea

  • EDD= LMP + 1 year - 3 months + 7 days

determining gestational age- uterine size

• starting around 12 weeks can use palpation via abodominal exam to estimate gestational age

• after 20 weeks symphysis to fundal height in cm shoudl correlate with week of gestation

fundal height

• distance from top of pubic bone to the top of the uterus

• helsp asssess babys growthm determine gestational age, and confirm baby due date

determining gestational age- US

• superior method to determine gestational age

• typically transvaginal during 1st trimester

• can calculate gestational age via crown - rump length (CRL) btwn 6 adn 13 weeks gestation

initial prenatal visit

• ideally during 1st trimester by 10weeks gestation

• complete hx-

  • ob- gravidity/parity, outcomes of all preg

  • medical; CV, GI,e ndocrine, MH disorders in particular may require monitoring

  • surgical

  • fhx

  • social

• physical exam- vitals, BMI, pelvic exam

initial prenatal visit- confirmation

• US to confirm intrauterine preg, determine gestational age, assess for multiples, and screen for congenital anomalies

• standard labs

  • CBC and ferritin

  • ABO and RhD type/antibody screening

  • antibodies to rubella adn varciella

  • urine protein/culture (treat asx bacteriuria if present)

  • HIV/syph

  • hep B/C

  • C/Gn

initial prenatal visit- discussion of genetic testing

• all shoudl be offered prenatal noninvasive genetic screening

• depending on results, amteral age, risk factors, and personal preference, can decide whether to pursue dx testing

initial prenatal visit- non invasive screening

• blood drawn from pt to screen for risk of certain aneuploidy/genetic conditions

• us ematernal blood to analyze fetal DNA

• cal ID those at high risk of:

  • trisomy 21/18/12 and sex chrom aneuploidies

  • CF

  • spinal muscular atrophy

  • hemoglobinopathies (thalassemia, sickle cell)

• ± nuchal translucency (NT) testing via US

fundal height by gestational age- 12 weeks

• fundus just above pubic bone

fundal height by gestational age- 36-38 weeks

• fundus usually right up under sternum

fundal height by gestational age- 40 weeks

• fundus drops as presenting part drops down into pelvis

initial prenatal visit- invasive dx testing

• dx procedures that can help confirm presence of genetic/fetal condition

• should be offered to anyone who has positive noninvasive screening

• can also he offered alternative to noninvasive screening (esp fro those who are high risk or >35yo)

• chorionic cillus sampling can be done btwn 10-13weeks or amniocentesis btwn 15-20weeks

chronic villus sampling

• procedures that collects small samples of placenta

  • transcervical or transabdominal aspiration of chronic villi via UA- guidance

  • out pt

chronic villus sampling indications

• prenatal genetic studies

• provides same genetic info as amniocentesis but higher rate of dx uncertainty

chronic villus sampling timing

• btwn 10-13 weeks

• earlier than 10 weeks= increased ridk of limb reduction defects

• later than 13 weeks= safe but amniocentesis preferred once pt reaches 15 weeks

chronic villus sampling potential complications

• transabdominal tech associated with fewer complications compared to transcervical

• preg loss

• limb reduction defects

• failure to obtain sample

• maternal cell contamination

• vaginal spotting

• infection 9rare)

amniocentesis

• procedure that inserts needle transabdominally to draw off amniotic fluid from uterine cavity

amniocentesis indications

• prenatal genetic studies (MC)

• eval for featl infectionm anemia, blood type, hemoglobinopathy, or neural tube defect

• therapeutic procedure to remove excess amniotic fluid

amniocentesis timing

• optimal btwn 15-18 weeks

• earlier than 15 weeks- greater risk complications

• later than 18-20weeks- safe but not preferable ifn preg term planned based on results

amniocentesis ptential complications

• often performed without local anesthetic or anticiotic prohylaxis

• temp leakage of amniotic fluid

• direct fetal injury (rare)

• transmission of infection if pt has viremia/bacteremia at time of procedure

• inoculation by bowel blora 9rare)

• preg loss (rare)

percutaneous umbilical blood sampling (PUBS)

• PUBS = cordocentesis

• procedure to gain acces to fetal blood

  • needle inserted into section of umbilical vein that inserts into placenta

• indications

  • dx eval of fetal disorders (such as fetal anemia)

  • indicated when other testing (CVS, amniocentesis) does not provide adequate info

• setting

  • prior to fetal viability - US or labor room

  • after viability- must have access to an OR in case of emergency C section

PUBS potential complications

• fetal bleeding at puncture site (20-30% of cases)

• cord hematoma

• fetal brady

• infection

• failure to onbtain specimen

• fetal loss

initial prenatal visit- assess indication for referral

• manternal fetal medicine subspec for high risk cases

• social services or case mgmt fro SE issue

• genetics counselor if indicated

initial prenatal visit- pt education

• concernign sx to look for and how to reach on call provider

• daily prenatal vitamin (folic acid to reduce risk of neural tube defect)

• foods to avoid, other dietary adjustments, est app weight gain)

• avoidanc of ETOH, tobacco, illicit drugs

• exercise

• vaccinations- COVID 19, Tdap, influenza and RSV

recommended weight gain during preg

if someone is under weight, they need to gain more weight during preg; someone over weight you want to gain smaller amnt of weight

preg and vaccination

• covid 19- ok in any tri

• Tdap- 3rd tri

• flu- ok in any tri

• RSV- 3rd tri

standard schedule for subsequent prenatal visits

• q4 weeks from 0-28 weeks gestation

• q2weeks from 28-36 weeks gestation

• q1 weeks from 36 weeks until delivery

routine assessment - subsequent visits

• pt weight and BP

• uterine fundal height

• new sx or sig events since previous visit

  • vaginal bleeding, leakign of fluid

• doc fetal HB

subsequent prenatal visits- assess maternal perception of fetal activity

• quickening- perceived early fetal mvmt usually occurs around 18-20 weeks getation

• perform daily “kick counts” after 28 weeks

• decreased featl activity requires further eval

baby kick count

• when to start counting

  • 28 weeks

• how often

  • BID or more

  • at same time each day

• how to count

  • sit comf or lie on side

  • record time of 1st mvmt

  • count until 10 mvmts

  • record time of 10th mvmt

  • hsoudl feel 10mvmts in 2 hours

fetal mvmt

• 13-25 weeks, but most commonly btwn 16-22 weeks

• initially- subtle flutters and wiggles

• later- kicks, punches and rolls

• freq

  • varies from baby to baby

  • vigorous kick s until 32

specific 2nd trimester tests

• discuss genetic testing if not already performed in 1st tri

• fetal anatomic scan

  • perform btwn 18-22 weeks

  • assesses placenta, umbilical cord, cervical length, fetal growth, and anatomic abnormalities

• 1 hour glucose tolerance test (GTT)

  • perform btwn 24-28 weeks

  • screens for gestational diabetes

  • glucose ≥245 at 1 hour is considered positive and warrants further testing (does NOT diagnose)

specific 3rd trimester tests

• in RhD neg pts

  • repeat RBC antibody screengin at 28 weeks and admin anti-D immune globulin

• repeat CBC

  • recheck fro anemia at beginnign of third tri

• group B strep (GBS)

  • screeening done btwn 35-37weeks

  • vaginal/rectal swab

  • intrapartum abx prophylaxis indicated for + pts to reduce risk of neonatal GBS

• repeat STI panel

specific 3rd trimester tests- fetal growth test

• routine fundal height checks- make sure they lien up with gestatinal age

• US assessment if fundal height is abnomral OR high risk for FGR

• RF:

  • placental abnormalities

  • maternal facors: vascualr dx, HTN, kidney disease, DM, tobacco /substance use

  • fetal factors: genetic abnromalitiesm congenital bnormalities, infections (CMV< syph, varciella, etc)

• US

  • if shows FGR:

    • surveillance of umbillical artery via doppler

    • non stress test (NST) and biophysical profile (BPP)

    • timing of delivery may be adjusted. base don results and gestational age

biophysical profile

• fetal HB

• fetal muscel tone

• fetal body mvmts

• fetal breathing mvmts

• amniotic fluid vol

specific 3rd trimester tests- determining antenatal fetal surveillance

• those a increased risk of antepartum fetal demise are monitored with NST /BPP

• RF:

  • FGR, maternal HTN, gestational diabetesm sickle cell, kindey dz, multiple gestation, SLE

• testing typically initialled at 32 weeks

• any report od decreased fetal mvmt (kick counts) in third trimester will require

specific 3rd trimester tests- determine fetal position

• startin at 34 weeks

• can often be determiend by physical exam (leopold maneuver) or confirmed via US if needed

specific 3rd trimester tests- screen fro accelerated fetal growth

• if there is concern that fetus is large for gestational age

• typically in cases of gestational diabetesm hx LGA, or abnormal fundla height checks

• US performed around 37 weeks

• can determine if there is an indication for cesarean fluid

placenta

• oragn of preg

• attaches fetus to uterine wall

• directs maternal metabolism to provide nutrients to support fetal growth

• exchanges

  • oxygen

  • nutrients

  • antibodies

  • waste prod

• consumes apprx half of oxygen and glucose supplied to uterus

fetal circulation

• placenta- low vascular resistance

• fluid filled featl lungs- high vascular resistanve

• causes right to left shunts

  • foramen ovale- blood shunted from right to left atria

  • ductus arteriosis- blood shunted fro pulm artery

fetal circ- blood flow

• placenta sends oxygenated blood to fetus through umbilical vein → flows into IVC→ RA→ foramen ovale → LA→ LV→ aorta

• venous return goes from SVC→ RA→ RV→ pulm artery→ most RV output bypasses lungs (fluid filled)→ patent ductus ateriosus→ desc aorta → umbilical artery→ placenta (where gas exchange occurs)

fetal circulation- lower levels O2

• blood in fetal circ has lower O2 level compared to extrauterine life

• due to:

  • fetal hemoglobin (HgbF)- increased O2 affinity compared to mature hgb

  • fetus deo snot require as much O2- doe snot need to maintain thermoreg and many functions

  • preferential flow- blood with higher O2 content is delivered to vital organs

• low O2 also causes pulm vasoconstriction due to hypoxemia whixh contributes to the high vascular ressitance and therefore right to left shinting

fetal circulation- changes during delivery

• umbilical cord clamped= rapid changes form intrauterine to extrauterine life

• initial breaths drive alveolar fluid from air spces into interstitium and them pulm vasculature/lymphatics→ allows lungs to expand→ lowers pulm resistance

• low vascualr resistance fro placenta no longer part of circ→ increase in systemic ressitance and BP

• these changes reverse blood flow across ductus arteriosus (now left to right) → leads ot to constrict and functionally close within 10-15 hoirs after delivery

• increase in pulm venous return to LA→ pressure in LA eventually exceeds pressure in PA→ flap of foramen ovale closes (Perm fusion not complete until 2yo)

cardiovascular changes

• rise in resting HR

• changes in BP

  • decreases in 1st/2nd tri, greater for diastolic which widnes pulse pressure

  • in 3rd tri BP returns to baseline and may rise above that towards and of preg

• systemic vasodilation causing reduced vascular resistance

• cardiac outpt increases 30-40% above pre preg levels

  • due to rise in blood vol, reduced systemic vascular resistance, and increased

cardiovascular changes pt. 2

• palpitations

• heart shifts as uterus enlarges

  • move left, anterior, adn rotates which moves apical impulse

  • gives illusion of cardiomegaly or CXR and causes left axis deviaition on EKG

• auscultatory changes

  • louder heart sounds, wide splitting of S1, systolic ejection murmus

• supine hypotensive syndrome

  • acute hypotension within few min lyign supine= ass tachy, sweating, and pallor

  • from uterine compression of IVC- greater risk after 20 weeks

respiratory changes

• chest diameter may increase

• diaphragm will be raised by 4 cm as uterus enlarges

• functional residual capacity decrease by about 20%

• sensation of dyspnea- air hunger during 1st or 2nd trimester

  • mech is not clear as uterus is still fairly small thses sx tedn to occur

• upper resp mucosa develops hyperemia and increased glandular activity

  • nasal congestion and epitaxis are common preg sx

hematologic changes

• plasma volume expands by 40-50%

  • helps with placental perfusion and acts as reverse aganst blood durign delivery

  • edema is common and worsening durign 3rd tri (do NOT use diuretics)

• RBC mass increases around 16 weeks - 25% greater than pre preg levels

  • imbalance btwn vol and RBC increases leads to dilutional anemia

  • physiologic anemia of preg peaks arounf 24 weeks- hbg hsoudl stay >10

• increase in coag factors

  • preg is a PROTHROMBIC state

  • helsp prevent excessive bleeding during separation of placenta

  • higher ridk of preg related venous thromboembolism

• increase in WBC count

  • usually stays within 9k-15k range

  • some may develop mild neutrophilia

  • if levels become >20k or associated with fever needs eval

• thrombocytopenia

  • gestational thrombocytopenia is a normal physiologic changes

  • levels declien as preg progress but typically stay >100,000

  • if levels fall <100,000 requires eval

gastrointestinal changes

• n/v aka morning sickness

  • starts around 5-6 weeks and usually resolves around 16-18 weeks

  • likely due to increasing hCG and progesterone levels

  • hyperemesis graidarum id severe n/v adn can result in weight loss

• stomach ind intestines are displaced as uterus enlarges

  • bloating and constipation are common

• increased acid reflux

  • hgiher level of progesterone cause lower esophageal spinchter to relax and decreases GI motility

• dietary cravings

  • can include pica- consumption of items not defined as food

gastrointestinal changes pt.2

• hemorrhoids

  • due to increase in local vneous pressure adn increase in cinstipation/decreased motility

• liver

  • serum albumin is reduced due to hemodilution

  • alkalaine phosphatase increases due to placental productin

  • lipid levels increase

  • oral health changegingivitis, dental caries, and changes in tastes

ptyalism can occur in 1st tri

endocrine changes

• thyroid changes

  • overall euthyroid but needs help meetin gincreased metabolic demands of preg

  • hCG can stimulate thyrpoid adn lead transient increase of T4 an T3

• parathyroid glad grows slightly to meet increased need fro calcium

• rate cortisol clearance id decreased

common maternal sx

• n/v

  • mgmt depends on severity

  • dietary changes, avoid triggers, ginger supp, acupressure wristbands

  • for nausea

    • pyridoxine (vit B6) first line

    • doxylamine- pyridoxine

  • for nausea + vom can add:

    • diphenhydramine

    • promethazine

    • ondansetron- ACOG cautions use against while <10 weeks

  • monitor for hyperemesis gravidarum which can cause hypovolemia, electrolyte imbalances, adn in some cases require hospitalization

common maternal sx- GERD

• lifestyle changes- elevate HOB, small/frequent meals, avoid dietary triggers

• antacids- tums

• sucralfate

• H2RAs- famotidine

• PPIs

common maternal sx- constipation

• increased fiber adn fluids

• lactulose or bisacodyk

• docusate if associated hemorrhoids are present

common maternal sx- nasal congestion

• if strictly related to preg usually does not respond well to meds

• will resolve withni 1-2 week safter giving birth

common maternal sx- trouble sleeping

• maintian regular sleep schedule

• avoid liquids at least 2 hours before goign to bed

• use preg pillows

• avoid napping

• can try mealtonin as first line pharm

common maternal sx- leg cramps

• calf stretches

• walking and axericse

• leg elevation

common maternal edema

• avoid standigni for log periods of time

• sleep oin left side

• wear suppoet hose or compression stockings

• AVOID diuretics

common maternal sx- back-pelvic pain

• wear shoes with good support

• sleep on side with pillow bten knees

• apply heat, cold, adn massage

• exercise adn stretching

• physical therapy

• acetaminophen