Is a White Blood Cell (WBC) count of 18,600 considered normal during pregnancy?

White Blood Cell Count During Pregnancy

Normal WBC Ranges in Pregnancy

A white blood cell (WBC) count of 18,600 during pregnancy is considered within the normal physiological range and does not require intervention. During pregnancy, there is a significant physiological increase in WBC count compared to non-pregnant women.

According to the most recent evidence, the normal reference range for WBC count during pregnancy is:

• First trimester: 5.7-15.0 × 10^9/L
• Second and third trimesters: 5.3-25.3 × 10^9/L (during labor) 1

The elevated WBC count during pregnancy is primarily driven by:

• A 55% increase in neutrophils (normal range: 3.7-11.6 × 10^9/L)
• A 38% increase in monocytes (normal range: 0.3-1.1 × 10^9/L) 2

Physiological Basis for Elevated WBC in Pregnancy

The increase in WBC count during pregnancy is a normal physiological adaptation and occurs due to:

1. Hormonal changes (estrogen and progesterone)
2. Stress response to pregnancy
3. Increased bone marrow production
4. Decreased margination of white blood cells

This leukocytosis remains stable between 8-40 weeks of gestation 2, with a further significant elevation during labor and delivery.

Clinical Implications

While a WBC count of 18,600 is within normal limits for pregnancy, it's important to note:

• The upper reference limit for total WBC is elevated by approximately 36% during pregnancy compared to non-pregnant women 2
• WBC counts can be further elevated during labor, with a normal range extending up to 25.3 × 10^9/L 1
• Fifteen women in a study had WBC counts >25.3 × 10^9/L (range 25.4-33.5 × 10^9/L) without evidence of severe sepsis 1

When to Be Concerned

A WBC count should raise concern when:

1. It exceeds the upper limit of 25.3 × 10^9/L
2. It is accompanied by clinical signs of infection (fever, tachycardia, hypotension)
3. There is a rapid rise in WBC count between measurements
4. There are other abnormal laboratory values suggesting infection

Potential Associations with Pregnancy Outcomes

Recent research suggests associations between elevated WBC counts and certain pregnancy complications:

• Higher WBC counts in the first and second trimesters have been associated with increased risk of:
  • Gestational hypertension (OR 1.18 and 1.10)
  • Pre-eclampsia (OR 1.14 and 1.10)
  • Gestational diabetes mellitus (OR 1.06 and 1.10)
  • Preterm birth (OR 1.12,1.10, and 1.12 across all trimesters) 3

However, a single WBC value of 18,600 without other clinical concerns falls within the normal physiological range for pregnancy and does not independently warrant additional evaluation or intervention.

Recommendations

1. Document the WBC count as within normal limits for pregnancy
2. No additional laboratory testing is needed based solely on this WBC value
3. Continue routine prenatal care
4. Consider repeating the CBC if there are clinical signs of infection or inflammation

Remember that interpretation of WBC count in pregnancy should always use pregnancy-specific reference intervals rather than non-pregnant values to avoid unnecessary investigations and interventions.