Prenatal Care
1.
Preconception
a.
Folic Acid Supplementation – Prevention of
neural tube defects
i. 400mcg
in low risk women
ii. Women
who have a history of a neural tube defect are considered higher risk and
require 4mg folic acid daily supplementation
iii. Folic
acid supplementation should not be obtained by taking multivitamins as it can
result in Vitamin A toxicity and teratogenicity. Women should not take more
than 5,000IU of Vitamin A daily (it is why women cannot take Retinoic Acid and
become pregnant).
1.
Microcephaly, Cardiac Anomalies, Miscarriage in
the first trimester
b.
Inter-Pregnancy Interval
c.
Exercise/Diet
d.
Smoking Cessation
e.
Genetic History
f.
Medical Optimization
2.
Prenatal Care
a.
Laboratory Testing and Imaging
i. Initial
Prenatal Battery
1.
Blood Type, Antibodies
a.
Rh negative patients require Rhogam at 28wks and
after delivery (unless fetus is Rh negative, or FOB is tested and known Rh
negative)
b.
Antibodies can attack fetal RBCs causing anemia
or hydrops
2.
Syphilis
3.
HIV
4.
Rubella
a.
MMR postpartum (live vaccine)
5.
Hepatitis B
6.
Urine Culture
7.
CBC
8.
Gonorrhea/Chlamydia
9.
Assess if patient is due for cervical cancer
screening
10. Optional:
a.
Hepatitis C
b.
Urine Drug Screen
c.
Varicella
ii. Aneuploidy
Screening
1.
Testing for chromosomal abnormalities and neural
tube defects (NTD)
2.
First Trimester Screening (FTS) (11w0d-13w6d)
a.
Nuchal translucency ultrasound plus serum tests
i. NT
is increased in NTD
b.
b-HCG
i. Increased
in T21
c.
PAPP-A
i. Decreased
in T21
d.
A FTS should be followed by a second trimester
AFP to better assess for NTD
3.
Second Trimester Testing (15w0d-20w6d)
a.
AFP
i. Decreased
in T21
ii. Decreased
in T18
iii. Elevated
in NTD
b.
Unconjugated estriol
i. Decreased
in T21
ii. Decreased
in T18
c.
hCG
i. Increased
in T21
ii. Decreased
in T18
d.
Inhibin A
i. Increased
in T21
4.
cffDNA
a.
Identify and evaluate genetics of fetal DNA
floating in maternal serum
5.
Invasive (Confirmatory) Testing
a.
Chorionic Villus Sampling
i. Obtain
small sample of placenta
b.
Amniocentesis
i. Obtain
amniotic fluid
iii. Second
Trimester
1.
Screening for Gestational Diabetes (25-28w)
a.
1hr Glucola (50g)
i. 1
hr <135
b.
3hr Glucose Tolerance Test (100g)
i. Fasting
<95
ii. 1hr
<180
iii. 2hr
<155
iv. 3hr
<140
2.
CBC
3.
Optional
a.
Syphilis
b.
HIV
4.
TDaP (28w)
5.
Rhogam if indicated
iv. Third
Trimester Laboratory Testing (>36w)
1.
Gonorrhea/Chlamydia
2.
Group B Strep
v. Ultrasonography
1.
Dating
a.
Women may have unreliable (or wrong) LMP
b.
Early ultrasound is more reliable for
determining accurate gestational age and EDD
i. As
a general rule, the gestational age is within the number of weeks of the
trimester of when the ultrasound was performed
c.
Ultrasound terminology for dating
i. Confirmed
by: the patient knows her LMP and the ultrasound agrees with it
ii. Set
by: the patient doesn’t know her LMP and therefore we base the EDD upon the
ultrasound
iii. Changed
by: the LMP and the ultrasound disagree, and therefore we base the EDD upon the
ultrasound
2.
Anatomy
a.
Assess internal organs and fetal structures
3.
Growth
a.
Assess interval growth of fetus between scans
performed at different times
b.
Determination of fetal size or weight
i. First
trimester generally uses the crown-rump length
ii. Beyond
that, four measurements are obtained and a multivariate equation determines the
EFW
1.
Head circumference
2.
Biparietal diameter
3.
Femur length
4.
Abdominal circumference
c.
There are many indications
i. Maternal:
Medical conditions, obesity
ii. Pregnancy:
multiple gestations, gestational hypertension
iii. Fetal:
fetal anomalies, small for gestational age
4.
Amniotic Fluid Assessment
a.
Polyhydramnios (too much fluid) and
Oligohydramnios (too little fluid) are associated with a variety of pregnancy
problems
i. Oligohydramnios:
<7cm amniotic fluid index (AFI), <2cm maximum vertical pocket (MVP)
ii. Polyhydramnios:
>25cm AFI, >8cm MVP
b.
Prenatal Visit
i. History
1.
Past Obstetrical History
a.
G/P
b.
Shoulder Dystocia, Postpartum Hemorrhage
c.
Pregnancy-Induced HTN, Gestational Diabetes
2.
Past Gynecology History
a.
Cervical dysplasia or procedures
b.
STIs
i. HSV
1.
Prophylaxis, SSE
3.
Past Medical/Surgery History
4.
Medications
ii. Physical
1.
Blood Pressure
iii. Prenatal
Vitamin
iv. Urine
Dip
v. Fetal
Heart Tones (every visit)
vi. Fundal
Height (FH), done >20w
1.
Measure from pubic symphysis to the uterine
fundus
2.
In cm, should be +/- 3 of the gestational age
a.
If FH too small, fetus is small for gestational
age (SGA) – order a growth ultrasound
b.
If FH too big, fetus is large for gestational
age (LGA) – order a growth ultrasound
vii. Flu
Vaccination – when indicated based upon season
viii.
Domestic Violence Screening
ix. Appointment
Spacing
1.
Generally appointments become more frequent
later in pregnancy
a.
0-28 weeks: q4w
b.
28-36 weeks: q2w
c.
>36 weeks: q1w
Image: FTS image marked showing the nuchal translucency and the nasal bone. Image from the Fetal Medicine Foundation.
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