From the Research
Yes, pregnancy can cause a mild elevation in white blood cell count, with the upper reference limit for total WBC elevated by 36% in pregnancy, driven by a 55% increase in neutrophils and 38% increase in monocytes. During pregnancy, the normal white blood cell count typically ranges from 5.7-15.0×10^9/L, as reported in a longitudinal study of 24,318 pregnant women 1. This physiological leukocytosis occurs primarily due to increased neutrophil production, stimulated by elevated estrogen levels and the body's stress response to pregnancy. The increase helps support the mother's immune system as it adapts to protect both mother and fetus while maintaining tolerance to fetal antigens.
Key Points to Consider
- The white blood cell count can increase to 15,000-18,000 cells per microliter, particularly during labor and the immediate postpartum period, as supported by a study of 17,737 pregnant women 2.
- This elevation is considered a normal adaptation rather than a sign of infection or inflammation.
- However, if white blood cell counts exceed 15,000 cells per microliter during pregnancy (outside of labor), or if accompanied by symptoms like fever or pain, further evaluation may be needed to rule out infection or other pathological conditions.
- The white blood cell count typically returns to pre-pregnancy levels within 4-6 weeks after delivery.
Clinical Implications
- Monitoring white blood cell counts is clinically relevant, as elevated levels are associated with an increased risk of infection and pregnancy-related complications, as reported in a study of 40,325 pregnant women 3.
- Clinicians should use pregnancy-specific reference intervals to distinguish between normal leukocytosis and pathological elevation of the white blood cell count during pregnancy and the initial postpartum period.
- A study published in 2024 provides comprehensive reference intervals for white blood cell counts during pregnancy, which can aid in the diagnosis and management of pregnancy-related complications 2.