11. Prenatal Care & Normal Pregnancy

Gestational age

- Time since 1st LMP, expressed in "completed weeks"

- Precedes fertilization

Developmental/fetal age

Age of conception, calculated from time of implantation (4-6 days after ovulation)

What is used estimate a due date?

Naegele's rule

Naegele's rule

Add 7 days to LMP, subtract 3 months, add 1 year

3 trimesters (# of weeks)

1 — Week 1 to end of week 12

2 — Week 13 to end of week 26

3 — Week 27 to end of pregnancy (up to 42 weeks)

Embryonic period

Time of fertilization (2 weeks GA) through 10 week gestational age

**Baby referred to as embryo

Fetal period

10 weeks GA (8 weeks after fertilization) through birth

**Baby referred to as fetus

Neonate (define)

First 28 days of life

Infant (fine)

Birth to 1 year of life

Live birth

Delivery of any infant demonstrating evidence of life (regardless of GA)

Fetal death

Death prior to completed delivery

Stillbirth

Fetal death at 20+ week of gestation

Abortion

Termination/extraction of products of conception with estimated GA <20 weeks (or <500g)

Preterm infant (define)

After 20 weeks, before 37 weeks

Term infant (define)

37 weeks to 41 6/7 weeks

Post-term infant (define)

>42 weeks

Large for gestational age (LGA)

Weight >90th percentile

Macrosomic infant

>4000g at birth

Fetal growth restriction

Fetal weight <10th percentile

Low birth weight infant

Live birth <2500g

Gravida (define)

Total number of times pregnant, regardless of outcome

**Count if currently pregnant

Parity (define)

Number of delivered/completed pregnancies to GA

TPAL

Term: >37 weeks

Preterm: 20-37 weeks

Abortion: <20 weeks

Living: Number of currently live children

Primigravida (define)

Pregnant for 1st time, or once before

Nullipara (define)

No live births >20 weeks

Primipara (define)

Completion of 1 pregnancy >20 weeks

Multipara (define)

Completion of 2+ pregnancies >20 weeks

What is considered to be pregnancy until proven otherwise in reproductive-aged female?

Second amenorrhea

Pregnancy S/S & onset (7)

- N/V — Early as 2 weeks, resolving ~13-16 weeks

- Breast changes — Tenderness (mastodynia), engorgement, Montgomery tubercles, early as 6-8 weeks

- Elevated basal body temp — 0.5F increase d/t progesterone

- Leukorrhea — D/t hormonal changes

- Chadwick's sign

- Hegar's sign

- Goodell's sign

Chadwick's sign

Bluish discoloration of cervix & vagina d/t congestion of pelvic vasculature

Hegar's sign

Widening & softening of uterus occurring around 6-8 weeks gestation

Goodell's sign

Softening of cervix occurring 4+ weeks gestation

MC method to confirm pregnancy

Urine hCG test

When can B-hCG be detected in maternal serum? Peak?

20-22 days after LMP (5-7 days after conception); Peak at 10-12 weeks then decrease

When does serum & urine B-hCG return to normal?

21-24 days after delivery or loss

Threshold for positive urine hCG vs. serum hCG

Urine: 5-50 mIU/mL

Serum: 2-4 mIU/mL (serum detects earlier)

Serial serum hCG tests can be used to evaluate for...

Threatened abortion, ectopic/molar pregnancy

When are fetal heart tones (FHTs) detectable? Normal HR?

Handheld doppler after 10 weeks; HR 110-160

What imaging & activity can be assessed in early pregnancy?

Transvaginal US

Cardiac activity — 6 weeks

Limb buds — 7-8 weeks

Limb movements — 9-10 weeks

What method is very accurate to determine gestational age? When?

Crown rump length (CRL) between 6-13 weeks

When would due date be determined by CRL rather than LMP?

EGA based on LMP >5 day discrepancy vs. CRL prior to 9 weeks gestation

At what gestational age does the fundal height (cm) correlate with GA (weeks)?

18-34 weeks

At what gestational age is the fundus at the umbilicus?

20 weeks

At what gestational age is the uterus palpable just at pubs symphysis?

8 weeks

At what gestational age is the fundus just below xiphoid?

36 weeks

At what gestational age does the uterus move into the abdomen?

12 weeks

At what gestational age is the fungus at midpoint between pubic symphysis & umbilicus?

16 weeks

Quickening (define & onset)

Maternal perception of fetal movement occurring between 18-20 weeks in primiparous & 14-18 in multigravida

Components of preconception visit/care

- Prenatal vitamins / folic acid — 400 mcg of folic acid (decrease risk of neural tube/cardiac abnormalities)

- Immunization, mental health, social issues

- Chronic medical conditions & meds

- FamHx of genetic disorders/risks

When should the 1st prenatal office visit occur?

ASAP in pregnancy

Main purpose of prenatal care visit

ID risk factors / high-risk pregnancies that can affect health of mother/baby

Obstetric history of initial prenatal assessment

- Outcomes of all previous pregnancies — Anesthesia, type of delivery, if past C-section → Indication & type of incision

- Review Fam, Surg, Social, Immunization history

Pelvic exam of initial prenatal assessment

- Assess AP diameter of body pelvis, shape/angle of pelvic outlet

- Palpate uterus & ovaries

- Cervical length & appearance — Avg by bimanual ~3-4 cm

Cervical length & appearance of nulliparous female

Cervical os closed

Cervical length & appearance of primi/multiparous female

External os dilated BUT internal os closed

When is a transvaginal US indicated for assessment of cervical length & appearance?

Suspected short/effaced cervix, or history of spontaneous preterm birth

Diagnostic workup of initial prenatal assessment

- Type & screen

- Hep B surface antigen, syphilis (VDRL), HIV

- Rubella, varicella zoster titer

- Trisomy 21, 18, 13 screen

- Hemoglobin electrophoresis (sickle cell/hemoglobinopathies)

- CF screen

- UA & culture

- GC & chlamydia (urine or endocervical)

- If Hx of gestation diabetes → 1 hour glucose challenge

- If no PAP/negative within 3 years → PAP for HPV

- High-risk → TB

1st trimeter genetic screening

- Pregnancy-Associated Plasma Protein A (PAPP-A), hCG, Hbg electrophoresis, CF — Assessed w/ maternal blood test at 1st prenatal visit

- Fetal nuchal translucency screening (nuchal fold thickness on US; assesses for Down's syndrome) — 12 weeks

- Maternal serum alpha fetoprotein (open neural tube defects) — 15-18 weeks

When would 2nd trimester maternal serum quad screen be indicated?

IF NO 1st trimester genetic screen, can be done between 15-20 weeks for neural tube defect/trisomies

Screening for aneuploidy

Cell-free DNA after 10 weeks GA

What should be offered to ALL patients, but especially those 35+ years at deliver/FamHx of chromosomal abnormalities?

Invasive diagnostic testing

Options for invasive diagnostic testing for chromosomal aneuploidy

- Chorionic villous sampling — 10-13 weeks

- Amniocentesis — 15-20 weeks

When is gestational diabetes screening indicated?

24-28 weeks

Frequency of visits for ongoing prenatal care for uncomplicated pregnancies

0-28 weeks: Every 4 weeks

28-36 weeks: Every 2 weeks

>36 weeks: Weekly

What is measured & compared to prior visits with ongoing prenatal visits?

- Maternal weight, BP

- UA

- Uterine fundal height

- FHTs

- Beginning at 26 weeks → Fetal size/position

- Eval for edema

Inadequate weight gain during pregnancy can result in...

Fetal growth restriction

Excessive weight gain during pregnancy can result in...

Macrosomic infant

ACOG recommendations for weight gain in pregnancy

Diagnostic workup of 3rd trimester evaluation

- Repeat CBC — Anemia eval

- Rh negative → Repeat antibody/type & screen

- Group B strep — 35-37 weeks

What water / hot tub temperatures should be avoided, especially in 1st trimester?

>100 F

Nicotine & cigarette smoking during pregnancy is associated with...

IUGR, placenta previa/abruption, preterm birth, low birth weight, SIDS, perinatal mortality

Alcohol consumption during pregnancy is associated with...

FAS: Growth restriction, cranial-facial abnormalities, mental retardation, cardiac defects, behavior abnormalities

Cannabis during pregnancy is associated with...

Low birthweight/stillbirth

Cocaine use during pregnancy is associated with...

Spontaneous aborption, preterm, pre-eclampsia, placenta abruption

Opiates & benzos during pregnancy are associated with...

Neonatal abstinence syndrome

Exercise recommendation during pregnancy

Encouraged 30+ mins of mod-intensity

Immunizations during pregnancy

- Flu season → Flu shot

- 3rd trimester → Tdap

- Risk → Hep A / B, meningococcal, killed polio

When can live vaccines be administered to pregnant individuals?

>1 month PRIOR to pregnancy OR postpartum

When should a pregnancy individual avoid intercourse until evaluated by clinician?

Preterm labor OR vaginal bleeding

Nutritional recommendations during pregnancy

60-80g protein/day, especially during 2nd half of pregnancy — Lean meat, low-fat dairy, vegetable proteins

In pregnancy, there are increased nutritional requirements for...

- Caloric intake — 300/day pregnancy; 500/day breastfeeding

- Iron, zinc, Ca

- Folic acid (0.4mg for most; 4mg for hx of neural defect, 1 mg/day with T1DM OR on valproic acid/carbamazepine)

- B12 — For vegetarians, Hx of gastric bypass, megaloblastic anemia

Prevention of infections during pregnancy

- Toxoplasmosis → Avoid litterbox, wash fruit/veg

- Listeriosis → Avoid soft cheese, raw milk, raw sprouts, cold deli meats

- Avoidance of sick contacts

Treatment of choice for syphilis in pregnancy

PCN + lab titers

Treatment of choice for chalmydia in pregnancy

Azithro/Amox

Treatment of choice for gonorrhea in pregnancy

Ceftriaxone + Azithro

Treatment of choice for genital herpes in pregnancy

Acyclovir — Prophylactic treatment starting at 36 weeks for decreased risk of outbreak during labor

**Active outbreak is indication for C-section

Treatment of choice for HIV in pregnancy

ART + monitor viral load & CD4

When is C-section indicated for HIV in pregnancy?

Viral load >1000

Treatment of choice for trichomonas in pregnancy

Metronidazole PO

Treatment of choice for candidiasis in pregnancy

Fluconazole

Treatment of choice for BV in pregnancy

Metronidazole PO

Common skin changes in pregnancy

- Melasma — Occurs after 16 weeks

- Linea nigra

- Striae — Appear late in pregnancy

- Spider telangiectasia — Stellate skin lesions & palmar erythema d/t estrogen

Pelvic ligament pain

- Relaxation of sacroiliac joints & pubic symphysis → Low back & pelvic pain

- Round ligament pain → Deep, sharp/stabbing sensation of abd around hips/groin worse wet changing positions, appears 2nd trimester

Barton Hick's contractions

- Tightening/pressure, mild/irregular uterine contractions

- Resolves w/ hydration & rest

- Onset around 28 weeks, increase with pregnancy

**DO NOT cause cervix to dilate OR get progressively stronger