Prenatal Care

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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