What initial blood work is recommended for pregnancy?

Initial Blood Work Recommended for Pregnancy

All pregnant women should undergo comprehensive blood work screening in the first trimester, including complete blood count, hepatitis B surface antigen, blood glucose screening, and blood typing to identify potential complications early and ensure optimal maternal and fetal outcomes. 1, 2

Essential First Trimester Laboratory Tests

Infectious Disease Screening

• Screening for hepatitis B surface antigen (HBsAg) is recommended in the first trimester to recognize and reduce the risk of HBV mother-to-child transmission 1
• Rubella, syphilis, hepatitis B virus, and HIV testing should be performed during preconception counseling or at the first prenatal visit 1
• Cervical cultures and Pap smear should be obtained at the initial visit 1

Hematologic Assessment

• Complete blood count (CBC) should be performed in the first trimester to screen for anemia, with hemoglobin <11.0 g/dL considered anemic 2, 3
• Blood typing and antibody screening should be performed to identify potential blood incompatibilities 1
• A second CBC should be performed at 24-28 weeks of gestation to reassess for anemia 2

Metabolic and Endocrine Screening

• Fasting blood glucose should be measured at the first prenatal visit to screen for pre-existing diabetes 1
• Risk assessment for gestational diabetes should be undertaken at the first prenatal visit 1
• Women with high risk for gestational diabetes (obesity, personal history of gestational diabetes, glycosuria, strong family history of diabetes) should undergo glucose testing as soon as feasible 1
• Thyroid-stimulating hormone should be tested in women with pre-existing diabetes 1

Renal Function Assessment

• Serum creatinine and urinary albumin-to-creatinine ratio should be measured, particularly in women with chronic hypertension or pre-existing diabetes 1
• Baseline renal function tests are important for women at risk of preeclampsia 1

Liver Function Assessment

• Liver enzymes (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase) and function tests (international normalized ratio, serum bilirubin, and serum albumin) should be performed in women with chronic hypertension 1
• Uric acid levels should be measured as elevated levels are associated with worse maternal and fetal outcomes 1

Second Trimester Screening

Aneuploidy and Neural Tube Defect Screening

• Multiple marker screening (AFP, hCG, uE3 with or without INH-A) should be offered to women unless amniocentesis is indicated based on history/age or they have elected first-trimester screening 1
• Maternal serum alpha-fetoprotein (MSAFP) screening for detection of open neural tube defects and anencephaly should be offered between 16-18 weeks gestation 1

Diabetes Screening

• Women with average risk for gestational diabetes should have testing at 24-28 weeks of gestation 1
• A 50-g glucose challenge test (Glucola test) or oral glucose tolerance test should be performed at 24-28 weeks 1

Special Considerations

Women with Chronic Hypertension

• More comprehensive baseline laboratory assessment is recommended, including complete blood count, liver enzymes, renal function, and uric acid 1
• These tests provide a baseline reference for detecting superimposed preeclampsia, which complicates up to 25% of pregnancies with chronic hypertension 1

Women with Pre-existing Diabetes

• Additional testing should include A1C, thyroid-stimulating hormone, creatinine, and urinary albumin-to-creatinine ratio 1
• Comprehensive eye examination should be performed to assess for diabetic retinopathy 1

Common Pitfalls to Avoid

• Failing to screen for hepatitis B in the first trimester, which is crucial for preventing mother-to-child transmission 1
• Missing the opportunity to identify and treat iron deficiency anemia, which accounts for 75% of all anemias in pregnancy 4
• Delaying glucose screening in high-risk women, which should be performed as early as possible in pregnancy 1
• Not repeating anemia screening in the second trimester (24-28 weeks), when hemoglobin levels <10.6 g/dL may predict anemia at delivery 5
• Overlooking the importance of baseline laboratory tests in women with chronic medical conditions, which are essential for monitoring disease progression and detecting complications 1