Prenatal Care: Introduction and Family Context

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Prenatal Care Introduction and Family Context

• T. Villela, MD
• Family and Community Medicine
• San Francisco General Hospital

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Objectives

• List important components of obstetric risk
  assessment
• Describe essential content of prenatal care
• Define common screening tests in pregnancy,
  including advantages and disadvantages
• Discuss context of prenatal care within a family,
  and interventions within that context

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Obstetric Risk Assessment

• Preconception
• Similar to antenatal assessment
• Can concentrate more on prevention
• Folic acid supplementation (0.4 mg/d)
• Sexually transmitted infections
• Nutrition
• MMR, varicella, OPV delay conception 3 months
• Td, Hep B
• Decrease exposure to tobacco, drugs, alcohol
• Antenatal

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Obstetric Risk Assessment Antenatal

• Goal is to plan for special risk care,
  consultation, or referral
• Tools risk-scoring systems continuous
  re-evaluation
• May not apply to low-risk pregnancies
• Real vs. theoretical risks. Many risks develop
  intrapartum and cannot be predicted
• Outcomes vary in number and specificity e.g.
  perinatal mortality vs. apgar score

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Obstetric Risk Assessment
Coopland (Manitoba) system Sens 11 Spec 98
PPV 45
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Objectives

• List important components of obstetric risk
  assessment
• Describe essential content of prenatal care
• Define common screening tests in pregnancy,
  including advantages and disadvantages
• Discuss context of prenatal care within a family,
  and interventions within that context

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Content of Prenatal Care

• Diagnosis
• Urine PT adequate positive at time of missed
  menses, or about an HCG level of 25 mIU/ml
• Dating
• LMP /- 2 weeks
• Bimanual /- 2 weeks
• Exam at 16 weeks or 20 weeks /- 2 weeks
• Ultrasound prior to 19 weeks /- 8
• 6 days at 10 weeks
• 10 days at 18 weeks

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A Brief Pause For Citrus Discussion
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Content of Prenatal Care

• Risk assessment
• Psychosocial evaluation
• Nutrition evaluation
• Review of medical history
• Review of reproductive history
• Review of family history
• Physical examination
• Blood pressure and pulse
• Height and weight
• Pelvic and pap

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Visit Frequency

• Up to 32 weeks
• Once every 4 weeks, and as needed
• 32 36 weeks
• Once every 2 weeks
• 36 weeks to delivery
• Once weekly
• Post partum
• 2 weeks (optional)
• 6 weeks

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Objectives

• List important components of obstetric risk
  assessment
• Describe essential content of prenatal care
• Define common screening tests in pregnancy,
  including advantages and disadvantages
• Discuss context of prenatal care within a family,
  and interventions within that context

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Screening Tests Initial

• Blood Pressure
• Height and weight
• Blood Type, Rh, antibody screening
• Hgb/Hct
• HepBSag
• RPR or VDRL
• Chlamydia
• HIV antibody
• Rubella Serology

• Hemoglobinopathy screening
• Amniocentesis or chorionic villus sampling for
  maternal age gt35 yrs
• Urine culture at 12-16 weeks or first visit
• PPD
• Pap smear
• Early GLT

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Screening Tests Initial

• Blood Pressure
• Preeclampsia screening
• Good association with improved outcomes
• Height and weight
• Good association with improved outcomes
• Blood Type, Rh, antibody screening
• Incidence of isoimmunization decreased from 10 to
  1.3 per 1000 births since introduction of RhoGAM
• RhoGAM at 24 28 weeks and at delivery if
  newborn is Rh pos
• Hgb/Hct
• lt 10 mod risk
• lt 8 high risk

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Screening Tests Initial

• HepBSag
• 20,000 births/year among women with active
  infection
• Newborn vaccine HepBIg at least 75 effective
  in preventing transmission
• RPR or VDRL
• Transplacental infection can lead to fetal death
  in up to 40 of patients
• Spec 75 confirm with MHA-TP
• Chlamydia
• 155,000 women infected at time of delivery
• Half of newborns will develop pneumonitis or
  conjunctivitis

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Screening Tests Initial

• HIV antibody
• ARV therapy in third trimester and at delivery
  can decrease transmission from 23 to less than
  8
• Rubella Serology
• Infection prior to 16 weeks associated with worst
  outcomes
• Vaccine contraindicated in pregnancy must delay
  pregnancy by three months
• Immunity is not 100 effective
• Hemoglobinopathy screening
• Identified carriers are offered screening of
  partner

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Screening Tests Initial

• Amniocentesis or chorionic villus sampling for
  maternal age gt35 yrs
• 14 weeks vs. 10 weeks gestation
• CVS cannot detect neural tube defects
• Miscarriage rates 0.25 vs. 0.5
• Genetics counseling referral
• Urine culture at 12-16 weeks or first visit
• Asymptomatic bacteriuria common, 5
• Untreated, up to 25 will develop pyelonephritis
• Treat gt100,000 of a single species of organism

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Screening Tests Initial

• PPD
• Recommended for immigrant populations and other
  high risk groups
• Post partum prophylaxis, include pyridoxine
• Treatment of active disease no different, except
  for the following contraindications
  streptomycin, pyrazinamide, ethionamide
• Pap smear
• Colposcopy if cervical dysplasia is found
• Treatment of non-invasive disease is usually
  postponed until after pregnancy
• Early GLT
• Previous LGA birth, strong family history

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Screening Tests 16 18 weeks

• Offer triple marker testing at 15-20 weeks
  correct dating of pregnancy critical to
  interpretation of results
• Alpha-fetoprotein (AFP) -- produced by fetal
  liver. Increased in open neural tube defect,
  twins. Decreased in Down syndrome
• Unconjugated Estriol (UE) -- produced by the
  placenta and fetal liver. Decreased in Down
  syndrome
• Human Chorionic Gonadotrophin (hCG) -- produced
  by the placenta. Increased in Down syndrome
• CXR if indicated for PPD

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Screening Tests 24 28 weeks

• GLT (50 gm)
• 140 PPV 22, NPV 99.7
• 130 PPV 17
• 3 hour GTT (100 gm) is used for diagnosis
• F 105 1h 180 2h 155 3h 140
• Abnormal fasting or any two other abnormal values
  is diagnostic
• Hgb/Hct
• RPR or VDRL
• If Rh neg recheck antibody screen and
  administer RhoGAM

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Objectives

• List important components of obstetric risk
  assessment
• Describe essential content of prenatal care
• Define common screening tests in pregnancy,
  including advantages and disadvantages
• Discuss context of prenatal care within a family,
  and interventions within that context

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Preconception Anticipation, Disappointment
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First Trimester Adjustment, Ambivalence
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Second Trimester Exploration, Fear
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Third TrimesterAnticipation, Impatience
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Fourth TrimesterDelight, Chaos
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Resources

• CHN prenatal website
• Referral guidelines
• Diabetes diagnosis and management
• Antenatal testing
• Much more.
• Daisy Gin, RN 206-5067
• BAPAC
• Perinatal treatment warmline 800-933-3413
• Genetics Testing Center