What blood work is recommended for pregnant women on their first visit?

First Prenatal Visit Blood Work

All pregnant women should undergo comprehensive blood work at their first prenatal visit, including complete blood count, blood type and antibody screen, hepatitis B surface antigen, HIV, syphilis, rubella immunity, and fasting glucose screening for diabetes risk assessment. 1

Essential Laboratory Tests - First Trimester

Hematologic Assessment

• Complete blood count (CBC) to screen for anemia, with hemoglobin <11.0 g/dL in the first trimester considered anemic 1, 2
• Blood type and Rh status with antibody screen to identify potential blood incompatibilities and prevent hemolytic disease of the newborn 1

Infectious Disease Screening

• Hepatitis B surface antigen (HBsAg) screening is mandatory at the first prenatal visit to prevent mother-to-child transmission, regardless of vaccination history 3, 1, 4
• HIV testing should be performed at the first prenatal visit 1
• Syphilis serology at the initial visit 1
• Rubella immunity testing to identify susceptible women who should receive postpartum vaccination 1

The USPSTF, American College of Obstetricians and Gynecologists, American Academy of Family Physicians, and CDC all strongly recommend universal hepatitis B screening at the first prenatal visit, as this enables timely administration of hepatitis B vaccine and immune globulin to newborns within 12 hours of birth, which is highly effective at preventing perinatal transmission 3, 4.

Metabolic and Diabetes Screening

• Fasting blood glucose should be measured at the first prenatal visit, particularly in women with risk factors for diabetes 3, 1
• Early glucose testing (12-14 weeks) is specifically recommended for high-risk women including those with BMI ≥30 kg/m², history of gestational diabetes, family history of diabetes, or high-risk ethnicity 3, 1, 5
• Women with average risk should have standard glucose screening at 24-28 weeks gestation 3, 1

Additional Testing for High-Risk Women

For women with chronic hypertension:

• Baseline liver enzymes and function tests 1
• Serum creatinine and urinary albumin-to-creatinine ratio 1
• Uric acid levels 1

For women with pre-existing diabetes:

• Hemoglobin A1c 1
• Thyroid-stimulating hormone (TSH) 1
• Serum creatinine and urinary albumin-to-creatinine ratio 1

Second Trimester Testing (24-28 Weeks)

• Repeat CBC to screen for anemia that may have developed during pregnancy 1, 2
• Glucose challenge test or oral glucose tolerance test for gestational diabetes screening in all women not previously diagnosed 3, 1, 5
• Maternal serum alpha-fetoprotein (MSAFP) screening at 16-18 weeks for neural tube defects 1

Common Pitfalls to Avoid

• Failing to screen for hepatitis B in the first trimester is a critical error, as this prevents timely prophylaxis for the newborn and increases risk of chronic HBV infection in the infant 1, 4
• Delaying glucose screening in high-risk women (BMI ≥30 kg/m², prior gestational diabetes) until 24-28 weeks misses the opportunity to detect pre-existing undiagnosed type 2 diabetes 3, 1, 5
• Not repeating screening at 24-28 weeks in high-risk women who initially tested negative for diabetes, as gestational diabetes typically develops later in pregnancy 5
• Overlooking baseline laboratory assessment in women with chronic hypertension or pre-existing diabetes, which is essential for detecting superimposed preeclampsia or disease progression 1