OB- Normal Pregnancy & Prenatal Care

What term refers to the maternal condition of having a developing fetus in the body & counts for current pregnancy or any past pregnancy whether or not it ended with a viable fetus?

Gestation

What is conception through the 8th week of gestation?

Embryo

What is the 9th week of gestation to delivery?

Fetus

What is the estimated age of the fetus that can be calculated based on menstruation vs clinical exam vs ultrasound?

Gestational age

What is Primigravida (Primip)?

First pregnancy

What is the Multigravida (Multip)?

2+ pregnancies

What is the expulsion of a nonviable embryo or fetus before 20 weeks gestation?

*can be spontaneous or induced

Miscarriage / abortion

What is the fetal demise after 20 weeks gestation?

Stillbirth

What is considered an early stillbirth?

20-27 weeks

What is considered a late stillbirth?

28-36 weeks

What is considered term stillbirth?

≥ 37 weeks

What is a low birth weight?

≤ 2500 g (5 lb 8 oz)

What is a normal birth weight?

2500 - 4500 g

What is a high birth weight (fetal macrosomia)?

≥ 4500 g (8 lbs 13 oz)

What is considered an immature infant?

Completed weeks 20 - <28

What is considered a premature infant?

Completed weeks 28 - < 37

What is considered a preterm infant?

Born before 37 weeks

What is considered a mature (term) infant?

Completed 37 weeks

What is considered a post mature infant (post dates)?

Completed 42 weeks

What is considered a full term infant?

37 - 42 weeks

When can a fetus survive outside of the womb?

22 weeks

What is the MCC of secondary amenorrhea?

Pregnancy

When does implantation bleeding occur?

10-14 days after conception

What is the first trimester?

Conception - 12 weeks & 6 days

What is the second trimester?

13 weeks - 27 weeks & 6 days

What is the third trimester?

28 weeks until full delivery

How long does normal human pregnancy last?

280 days / 40 weeks / 10 months

When does fertilization occur?

At time of ovulation (2 weeks after last normal period)

How is the estimated due date (EDD) from LMP calculated?

Nagele’s rule → take the 1st day of LMP, subtract 3 mos, add 7 days and add 1 year

How do you calculate GA from EDD?

[280 - (EDD - reference date)] / 7

What is gravida?

Number of times pregnant, carried to term or not

How many gravidas & paras do twins / multituplets count as?

1

What is Para?

Number of births that occurred after 20 weeks, viable or nonviable

What are the subcategories of Para?

Full term: ≥ 37 wks

Premature birth: 20-36 wks & 6 days

Abortion/miscarriages: < 20 wks

Living children

What is the GPA classification?

Gravida, para, abortus

What is the GPA classification of 2 full term singleton pregnancies, 1 twin pregnancy at 36 wks, & 4 living children?

G3P2104

How would you interpret G6P4024?

6 pregnancies, 4 full term births, 0 premature births, 2 abortions/miscarriages, 4 living children

How would you interpret G2P1001?

Currently pregnant patient who has 1 living child and is on her 2nd pregnancy

How are fundal heights calculated?

Measuring the distance from the superior edge of the pubic symphysis to the palpable fundus of the uterus (cm w/ soft tape measure)

*heights roughly correlate w/ gestational dates

What is the fundal height from 20 weeks to 36 weeks gestation?

Distance = weeks of gestation +/- 2

(ex: 24 weeks = 24 cm +/- 2cm)

When can fetal movement be detected on exam?

20-30 weeks

*fetal outline can be palpated at 22 weeks

What is the landmark to determine uterine size at 8 weeks?

Palpable at pubic symphysis

What is the landmark to determine uterine size at 12 weeks?

Becomes an abdominal organ

What is the landmark to determine uterine size at 16 weeks?

Midpoint between pubic symphysis and umbilicus

What is the landmark to determine uterine size at 20 weeks?

At umbilicus

What is the landmark to determine uterine size at 26-34 weeks?

Fundal height correlates with GA (± 2)

What is the landmark to determine uterine size at 36-40 weeks?

Decrease in fundal height

What is the MC diagnostic test used for pregnancy that is qualitiative & can detect as early as 8-14 days after conception?

Urine beta HCG

*best done w/ first morning void

What quantitative pregnancy test can detect as early as 5 days?

Serum beta HCG

*level correlates w/ GA in early pregnancy

How do serum beta HCG levels fluctuate in pregnancy?

Rise exponentially early, peak around 10 weeks, plateaus towards end of first trimester

What is a handheld device used to transabdominally to detect fetal heart tones (FHT) generally round 10-12 weeks as the uterus starts to move out of the pelvis?

Fetal doppler

What is a normal FHT?

120-160 bpm

When do heartbeats start to be detected by US?

5 ½ wks (90-120 bpm)

What are the time frames for when things can be measured with ultrasound?

5-12 wks: fetal crown rump length, FHT

20-30 wks: fetal biparietal diameter (skull width), femur length, abd circumference

>30 wks: accuracy decreases

*can also estimate fetal weight (EFW) & amniotic fluid index (AFI)

If in the 1st trimester, the US dating measures > 1 week difference GA than calculated by LMP, which do you go with?

US

If in the 2nd trimester, the US dating measures > 2 week difference GA than calculated by LMP, which do you go with?

US

If in the 3rd trimester, the US dating measures > 3 week difference GA than calculated by LMP, which do you go with?

US

In general, if there is no difference in GA calculations, should you stick with US or LMP?

LMP

What is used in the diagnosis of pregnancy (GA/maturity) with a mother presenting at term (37-42 wks) with no prior prenatal care?

Amniotic fluid analysis for surfactant → L:S ratio & PG presence

*US, HCG, & fundal heights are not accurate at these stages

What does a lecithin:sphingomyelin (L:S) ratio of 2:1 indicate?

Lung maturity

What does a L:S ratio of < 2:1 indicate?

Immature lungs → consider maternal steroid injection to decrease risk of of NRDS if in labor

What is one of the last fetal surfactants to develop (≥37 weeks), but is a less reliable indicator of lung maturity if the mother is diabetic or if amniotic fluid is contaminated?

Phosphatidylglycerol (PG) presence

When should the first obstetric US be done?

≥ 6 weeks→ earlier than this may be prior to cardiac development & can’t detect FHT or determine viability

*TV if < 6 wks, TA if > 6 wks

What is the first line RX for syphillis in pregnancy?

PCN

What is the first line RX for chlamydia in pregnancy?

Azithromycin

What is the first line RX for gonorrhea in pregnancy?

Ceftriaxone

What is the first line RX for HSV in pregnancy?

PO suppressive therapy at 35-36 wks; C section if active lesions

What is the first line RX for trichomoniasis in pregnancy?

Metronidazole (category B)

What is the first line RX for candidiasis in pregnancy?

Miconazole cream

What is the first line RX for BV in pregnancy?

Metronidazole (category B) after first trimester

What is used to assess fetal positioning in the 3rd trimester?

Leopold’s maneuvers

When is is nuchal translucency (NT) screening completed to measure fetus’s nuchal fold thickness?

11-13 wks

1.8 mm = normal

> 3.33 mm = soft marker for down syndrome

What is non-invasive prenatal testing/screening (NIPT)?

*blood test- MaterniT21, integrated screening

Screening for chromosomal fetal abnormalities between 10-20 wks

*inaccurate before 10 wks d/t insufficient fetal fraction

What does MaterniT21 evaluate for?

Common trisomies, select microdeletions (22q, 15q), rare sex aneuploidies, & fetal sex

does NOT evaluate for open neural tube deficits

What is integrated screening?

Combines maternal age risk, 1st trimester NT, & serum PAPP-A w/ 2nd trimester measurements of AFP, uE3, hCG, & DIA

*provides risk assessments for Down syndrome, open spina bifida, & trisomy 18

What has the highest detection rate and lowest false positive rate of detecting pregnancies with Down syndrome?

Integrated screening

What screening is completed at 10-13 weeks by inserting a needle transabdominally or transcervically into chorionic villi of placenta via US guidance, that allows for the option of early termination if abnormality is found?

*not routine; risk of miscarriage, infx, Rh sensitization

Chorionic villus sampling

When is the maternal serum alpha fetoprotein (AFP) level drawn?

15-21 wks (18 is most accurate)

What protein is produced by the fetal liver & yolk sac & is drawn during the second trimester to look for an increased risk of neural tube defects such as spina bifida?

AFP

In what conditions is the maternal serum AFP increased or decreased?

Elevated in spina bifida

Low in trisomy 18 & 21

When is the simple glucose challenge test (GCT) performed to screen for GDM?

24-28 weeks

How is the simple GCT test performed?

Nonfasting pt drinks 50g glucose soln & blood sugar is measured at 1 hr

*positive if > 140 → do a 3 hr GTT

What risks are associated with GDM?

Excessive fetal growth (> 9 lbs) - macrocosmic or LGA

birth comps, shoulder dystocia, preterm delivery, still birth, maternal risk of T2DM PP

What test performed at 15-20 wks (not routine) allows for the collection of amniotic fluid to provide a sample of fetal DNA to diagnose potential genetic defects?

*risk of clubfoot if performed before 15 wks

Amniocentesis

When is the US screening completed in the 3rd trimester to help determine final positioning of the fetus?

~ 36 weeks

When should a routine rectovaginal swab culture be performed to check for GBS?

35-37 wks

What is there an increased risk of if a pregnant woman has a GBS infection?

Preterm labor, amnionitis, endometritis, maternal wound infx, & transmission during delivery causing generalize sepsis of the newborn

What is the treatment for GBS in pregnancy?

1st line: PCN

Allergy: need a C&S to guide tx d/t resistance (macrolide)

When is a biophysical profile (BPP) completed in pregnancy?

32 weeks (sometimes earlier) in high risk pregnancy

After 40 wks in normal pregnancy

What does a biophysical profile (BPP) evaluate?

Fetal breathing, gross fetal tones, gross fetal movements, amniotic fluid levels, & NST (fetal HR monitoring w/o stress/contraction)

*each worth 2 pts; 10 pts total

What is a good or reassuring BPP score?

8-10

What BPP score may indicate early delivery and should be retested in 12-24 hours?

6-7

What BPP score is concerning & requires immediate management?

≤ 5

What test utilizes a fetal monitor to measure cardio accelerative response (FHR) in response to fetal movement, and is most reliable after 28-32 wks?

Non-stress test (NST)

What is the criteria for a reactive NST?

Baseline FHR 120-160 bpm

Presence of periodic accelerations (2 accelerations w/in 20 minutes) w/ increases of 15 bpm for 15s

What is the criteria for an abnormal (non-reactive) NST?

Absence of accelerations or presence of sporadic repeated decelerations of FHR

What vaccinations should be AVOIDED in pregnancy?

Live virus or bacterial → MMR, yellow fever, BCG, varicella, oral polio

What vaccines are okay to give in pregnancy?

Tdap (27-36 wks if no UTD), Hep A, Hep B, & pneumovax

*use caution w/ inactivated or assembled vaccines

How often should Tdap vaccinations be updated?

Mom: once each pregnancy no matter when the last one was (~ 27-36 wks no UTD)

Anyone of age that will be around the baby after delivery: every 10 yrs

What are the guidelines for pregnancy weight gain? (based on BMI before pregnancy)

BMI < 18.5 → gain 28-40 lbs

BMI 18.5-24.9 → gain 25-35 lbs

BMI 25-29.9 → gain 15-25 lbs

BMI > 30 → gain 11-20 lbs