White blood cell count

×10⁹/L · Full blood count & differentials

White blood cell count rises physiologically in pregnancy — non-pregnant 'high' flags are often false positives in late gestation.

Neutrophilic leukocytosis commonly pushes WBC toward 9–15 ×10⁹/L by T3. Infection workup still needs clinical signs, not the count alone.

How to read it

Use trimester-specific bands (Abbassi-Ghanavati / NHS antenatal). Pair with the differential when investigating fever or pain.

Stage	For the mother	For the baby
First trimester	Mild leukocytosis begins early — avoid over-calling infection on count alone.	Maternal immune adaptation supports implantation.
Second trimester	WBC continues to rise with neutrophil dominance.	Stable maternal immunity supports growth.
Third trimester	Upper reference often ~16–17 ×10⁹/L — 12 ×10⁹/L is commonly physiologic.	Peripartum counts rise further in labour.