Maternal Lab Results: Pregnancy Considerations

• Maternal lab tests and considerations during pregnancy are essential for monitoring the health of both the mother and the developing fetus, and detecting/managing potential complications.

Maternal Labs: CBC (Complete Blood Count)

• RBC: Evaluates for anemia; normal range during pregnancy is 3.75-5.0/mm.
• WBC: Detects infection or immunosuppression; normal range is 5,000-15,000; high levels indicate infection.
• Hemoglobin (Hgb): Measures the amount of red blood cells; normal range is 11.5-14 g/dL; low levels indicate hemorrhage.
• Hematocrit (Hct): Measures the percentage of red blood cells in blood volume; normal range is 32-42%; low levels indicate hemorrhage.
• Platelets: Assesses the blood's ability to clot; normal range is 150,000-350,000/mm; levels are needed prior to epidural placement; low counts are associated with thrombocytopenia, seen in HELLP syndrome.

Maternal Labs: Urinalysis

• Nitrates: Detects suspected urinary tract infection (UTI); a negative result is normal, while elevated levels indicate a UTI.
• Protein: Rules out pre-eclampsia and renal issues; a negative result is normal, while elevated levels indicate pre-eclampsia.
• Ketones: Evaluates for nausea/vomiting/diarrhea (N/V/D) and dehydration; a negative result is normal, while elevated levels indicate diarrhea, N/V, or hyperemesis gravidarum.
• 24-hour Urine Collection: Measures total protein in urine collected over 24 hours (urine stored on ice); a negative result is normal; >300mg/24 hours indicates mild pre-eclampsia, and >500mg/24 hours indicates severe pre-eclampsia.

Maternal Labs: Electrolytes

• Magnesium: Checks magnesium levels, especially with Magnesium Sulfate (MgSO4) administration; normal range is 1.7-2.2 mg/dL; if MgSO4 is infusing therapeutic levels are 4-7 meg, and higher levels can lead to complications/toxicity.
• BUN: Evaluates kidney function; normal range is 6-20 mg/dL; abnormal results assess kidney function.
• Creatinine: Assesses glomerular filtration; normal range is 11-20 mg/kg/24hrs; abnormal results assess kidney function.
• Liver Function Tests (LFT): Alanine aminotransferase (ALT): Liver function; the normal range is 7-35 units/L; elevated levels indicate HELLP syndrome.
• Aspartate aminotransferase (AST): Liver function; normal range is 10-36 units/L; elevated levels indicate HELLP syndrome.

Maternal Labs: Coagulation Studies

• Prothrombin Time (PT)/International Normalized Ratio (INR): Assesses coagulation; normal range is 0.8-1.2; checked during pregnancy related to bleeding or hemorrhage.
• Partial Thromboplastin Time (PTT): Assesses coagulation (bleeding time); normal range is 21-35 seconds; checked during pregnancy related to bleeding or hemorrhage.
• Fibrinogen: Assesses coagulation; levels are normally 400mg/dL (elevated during pregnancy); elevation increases risks of deep vein thrombosis (DVT) and pulmonary embolism (PE).
• D-Dimer: Detects clots, pulmonary embolism, and disseminated intravascular coagulation (DIC); normal range is less than 500 ng/ml; increased levels suggest PE; caution is advised as this test is positive in all patients after a trauma or surgery.

Prenatal labs

• Human Chorionic Gonadotropin (HCG): Detects early pregnancy, monitors levels in high-risk pregnancies, and monitors for trophoblastic tumors; in the first 4 weeks of pregnancy, levels double every 48 hours; verifies pregnancy, and levels are checked with Molar Pregnancy (x 1 year).
• Blood type/RH Factor: Identifies blood type and Rh factor; Types include A, B, O, AB; Rh is either negative or positive; used to administer blood products if needed and to identify if Rhogam is needed.
• Rubella (German measles) antibodies: Identifies if the mother has immunity from past vaccination; immune (positive antibodies >10 IU/ml); if non-immune or equivocal, after delivery prior to discharge, the mother will receive an MMR vaccine (live virus: not safe in pregnancy).
• RPR/VDRL (Rapid Plasma Reagin/Venereal Disease Research Laboratory): Prenatal lab to assess if the mom has been exposed to Syphilis; non-reactive; a state-ordered prenatal test; reactive Treponemal tests are the definitive methods for diagnosis of syphilis.
• Hepatitis B: Detects HBV; negative antibodies; if the mom is positive or unknown the baby will receive HBIG.
• HIV: Prenatal test: Human Immunodeficiency virus; negative antibodies; Can be drawn at the hospital if not completed prior with a consent.
• Hemoglobin A1C: Measures the amount % of glycated hemoglobin (hemoglobin coated with glucose); results from the past 2-3 mos; normal range is 4-7%; elevated is 5.7-6.4%, pre-diabetic range; determines if diabetes is present, and if the diabetes is being managed successfully.
• GBS: Group B Streptococcus: Prenatal screening: Vaginal swab at 36-37 weeks; negative; if positive, the mother is treated in labor (Penicillin) to protect the neonate during a vaginal delivery.
• L/S Ratio (lecithin/sphingomyelin): A sample of amniotic fluid is removed with an amniocentesis; 2:1 ratio (mature lungs); this test is done to test for lung maturity in preterm neonates.
• Oral Glucose Tolerance Test: To diagnosis: gestational diabetes; 4 blood draws are done over 3 hours. Clients will ingest a drink high in glucose and evaluate how their blood glucose responds.
  • Fasting BG: <95
  • GTT 1 hour: <140
  • GTT 2 hours: <120
  • GTT 3 hours: <95
• TORCH Panel: Maybe done in the prenatal period to diagnose acute, congenital and intrapartum infections; negative.
  • Toxoplasmosis: Common with cats
  • Other infections (hepatitis and chlamydia).

Newborn Labs

• Rubella: Non-immune individuals will receive PP
• Cytomegalovirus: Common amongst childcare workers.
• Herpes Simplex: If first or active outbreak, c-section required.
• Coombs: Blood test at birth for infants with a maternal blood type of type O or Rh negative; negative; if positive could indicate hemolytic anemia of the newborn (jaundice)
• CRP (C-Reactive Protein Test): Inflammation marker synthesized in the Liver; Less than 1.0 mg/dl; Elevated in newborns with infection or sepsis
• I:T Ratio: Collected in conjunction with other newborn labs to assess for potential infection. Calculated by dividing immature neutrophils/ Total neutrophils; <0.16-0.20 (less than 20% should be band cells); Elevated in newborns with infection or sepsis, called a "left shift". Bands Cells (immature neutrophils) 0-2 cells per 100. Segmented Neutrophils 80% or greater of total neutrophils
• Blood Cultures: Used to determine if there is an organism (viral, bacterial, or otherwise) growing in the bloodstream, indicating sepsis; negative; draw 2 samples from different locations, do not start antibiotics prior, results evaluated at 24 h/48/72 hrs.
• Bilirubin: Routine test on all babies to evaluate for hyperbilirubinemia (Jaundice); dependent on hours of life, but typically less than 5 dg/L in a 24 hour sample; a Bili-tool is used at most hospitals to calculate the results and days of life.
• BG: 4 hours: Used to identify hypoglycemia in at-risk babies; 40 mg/dL or greater; See AAP guidelines for precise determination of abnormal blood sugar management.
• BG: 24 hours: Used to identify ongoing hypoglycemia; 50 mg/dL or greater; See AAP guidelines for precise determination, that could be the result of an inherent metabolic disorder; of abnormal blood sugar management.

Interpreting maternal lab results during pregnancy requires considering gestational age-specific normal ranges due to physiological changes. Deviations from non-pregnant adult ranges are common and not always indicative of pathology. Accurate interpretation ensures appropriate management and avoids unnecessary interventions.