What is included in routine prenatal blood work?

Routine Prenatal Blood Work Components

Routine prenatal blood work includes blood type and Rh(D) antigen status, antibody screening (indirect Coombs test), complete blood count with differential and indices, serologic testing for infectious diseases, and genetic screening tests. 1

First Trimester Blood Work

• Blood type and Rh(D) antigen status to identify Rh-negative women who will need monitoring and potential Rh immunoglobulin administration 1, 2
• Indirect Coombs test (antibody screen) to evaluate for circulating red blood cell antibodies that could cause alloimmunization 1
• Complete blood count (CBC) with differential and indices to assess for anemia and other hematologic abnormalities 1
• Kleihauer-Betke stain for fetal hemoglobin to detect fetomaternal hemorrhage 1
• Serologic testing for infectious diseases:
  • Parvovirus B19 serology 1
  • Syphilis testing (review or repeat) 1
  • Consideration of acute phase titers for cytomegalovirus and toxoplasmosis 1
• Hepatitis B surface antigen (HBsAg) screening to identify women at risk of transmitting HBV to their infants 1
• Mean corpuscular volume (MCV) assessment, particularly important if <80 fL, which may indicate thalassemia carrier status 1

Genetic Screening Tests

• First-trimester screening typically includes:
  • PAPP-A (pregnancy-associated plasma protein A) 1
  • Free beta-hCG or total hCG (human chorionic gonadotropin) 1
  • These markers, combined with maternal age and NT (nuchal translucency) ultrasound measurement, are used to calculate risk for chromosomal abnormalities 1

Second Trimester Blood Work

• Quad screen (if not doing integrated or sequential screening):
  • Alpha-fetoprotein (AFP)
  • hCG (human chorionic gonadotropin)
  • Estriol
  • Inhibin A 1
• For women undergoing sequential or integrated screening, second-trimester blood samples are collected to measure additional markers that, combined with first-trimester results, provide more comprehensive risk assessment 1
• Repeat antibody screening for Rh-negative women at approximately 25-28 weeks gestation 2

Special Considerations

• For Rh-negative women, non-invasive fetal RhD prediction using cell-free DNA at around 25 weeks gestation 2
• For women with positive antibody screens, additional monitoring includes:
  • Antibody specificity and titer determination 2
  • Fetal genotyping using cell-free DNA for relevant blood group antigens (RhD, K, Rhc, RhC, RhE, ABO) 2
  • Serial monitoring of antibody titers 2
• For women at high risk for chromosomal abnormalities, non-invasive prenatal testing (NIPT) using cell-free DNA may be offered 3

Important Caveats

• The specific tests included in routine prenatal blood work may vary based on regional guidelines, practice patterns, and individual risk factors 1, 2
• Timing of tests is critical - first trimester screening must be performed within specific gestational age windows for accurate risk assessment 1
• Women identified with alloantibodies require specialized monitoring throughout pregnancy, including potential middle cerebral artery Doppler studies to assess for fetal anemia 1, 2
• Positive screening results typically require confirmation with diagnostic testing such as amniocentesis or chorionic villus sampling 4
• Laboratory quality control is essential to ensure accurate results, particularly for genetic screening tests 1