MD Notes

creation date: 2024-12-29 14:25
tags: Anatomy & Physiology Incomplete

Uncomplicated Pregnancy

First Trimester (Wk 1+0 - 12+6)

Fetal Development

Maternal Changes

Placenta

Clinical Components

Notable Conditions

Nausea and vomiting

  • Develops week 5, worst at week 9, and improves week 16
  • 50-80% develop nausea, 50% nausea and vomiting, 1% develop hyperemesis gravidarum

Indicated Testing & Investigations

First prenatal appointment
Blood tests:

  • Blood type and Rh factor
  • Rubella immunity
  • CBC (anemia/iron deficiency)
  • Hep. B serology (risk of asymptomatic transmission to infant)
  • VDRL (syphilis)
  • HIV testing
  • STI testing
  • Blood disorders if high risk

Simple in-office calculations:

  • Gestational age = time since last menstrual period
  • Fetal age = time from conception date (~2 weeks less than gestational age)
  • Estimated date of confinement (EDC) = ~280 days gestational age (Naegele’s rule)

Dating ultrasound (week 6-10):

  • Accurate estimation of gestation age using crown-rump length (GA 7-10 weeks)
  • Cardiac activity and anatomy

Genetic Testing
Enhanced First Trimester Screening (eFTS):

  • Consist of an ultrasound (nuchal translucency) and bloodwork
  • Between GA 11+2 - 13+3 weeks.

Non-Invasive Prenatal Testing (NIPT):

  • Very sensitive and specific testing through fetal/placental DNA testing from maternal blood
  • Available week 9+, for specific indications (or out of pocket cost)
  • Also provides gender determination

Routine Interventions & Management

Second Trimester (Wk 13+0 - 27+6)

Fetal Development

Maternal Changes

Clinical Components

Notable Conditions

Indicated Testing & Investigations

Genetic Testing
Second Trimester Screening (STS):

  • Similar to eFTS if it was missed

Gestational Diabetes Testing

  • Screening for asymptomatic GDM is done through glucose challenge and tolerance testing. A two-step approach is preferred but one step tolerance test is also available.
  • Done during GA 24-28 weeks; consider doing it <20 weeks if high risk

Routine Interventions & Management

Vaccinations
RhoGAM for Rh- mothers at 26-28 week and within 72 hours of birth of Rh+ baby

  • Note: if at any point there is suspicion of mixing, give RhoGAM immediately and then ever 12 weeks until birth

Tdap at 27-32 week

Hep B if no immunity or high risk

Third trimester (Wk 28+0 - birth)

Fetal Development

Maternal Changes

Clinical Components

Notable Conditions

Indicated Testing & Investigations

Maternal Investigations
VDRL for syphilis

  • False positives can come from Viral infections, Drugs, Rheumatic fever, Lupus/Leprosy
    Group B Streptococcus
  • Routine at week 36 - 37+7 or prior to labour if early
  • Positive culture indicates prophylaxis
  • Negative test is valid for 5 weeks before a repeat swab is needed
    Symphysis Fundal Height (SFH)
  • Confirm it matches gestational age (should be ~ cm = week between week 24-36 GA)

Fetal Investigations
Non-Stress Test (NST)

  • Measures how fetal heart rate responds to fetal movement
  • Non-reactive may suggest hypoxia, sleep, or gestational age too early
    Biophysical profile
  • Ultrasound for fetal movement, tone, breathing, amniotic fluid volume
    Anatomy ultrasound
  • Ultrasound for brain structure, umbilical cord, biometry, and that size corresponds to gestational age

Routine Interventions & Management

Vaccinations
RSV

  • Available week 32-36
  • Infant version is typically better and given to the infant 48-72h after birth