The expected physiologic change
Labor is a period of intense physical work, and several laboratory values and vital signs change as a result. One of the most striking is the white blood cell count, which may rise to about 25,000 to 30,000/mm³ during labor without any infection. A count of 22,000/mm³ (22 × 10⁹/L) in a woman with no other abnormal findings is therefore within the expected range. A rise in white blood cells is a recognized physiologic change of labor, but it is always interpreted together with temperature, pulse, and other signs.
Why white blood cells rise
The stress of labor and the physical effort of contractions release stress hormones that mobilize white blood cells into the circulation. This leukocytosis does not by itself indicate infection. Because of it, a single high count in labor is not used alone to diagnose chorioamnionitis or other infections; fever, maternal or fetal tachycardia, uterine tenderness, and foul-smelling amniotic fluid are more meaningful signs.
Blood pressure in labor
Blood pressure normally rises during contractions, which is why it is measured between contractions. This client's reading during a contraction (150/96 mmHg) could partly reflect that effect, but her reading between contractions is 142/90 mmHg, up from 112/72 mmHg on admission. Watch out! A reading of 140/90 mmHg or higher between contractions is in the hypertensive range and is not a labor effect. It needs follow-up for hypertensive disorders of pregnancy.
Pulse and temperature
A resting pulse of 122/min between contractions is not a normal labor change; it can point to dehydration, infection, hemorrhage, or uncontrolled pain. A temperature of 38.2 °C (100.8 °F) is fever. Labor may cause a slight rise in temperature from exertion and dehydration, but a true fever calls for assessment for infection, particularly when membranes have ruptured, although here they are intact.
| Finding | Expected in labor? | Action |
|---|
| WBC 22,000/mm³ | Yes, up to about 25,000 to 30,000/mm³ | Interpret with other signs |
| BP 142/90 mmHg between contractions | No; hypertensive range | Report and monitor |
| Pulse 122/min at rest | No | Assess for dehydration, infection, bleeding, pain |
| Temperature 38.2 °C | No; fever | Assess for infection |
Exam takeaway
Leukocytosis up to about 25,000 to 30,000/mm³ can be normal in labor; hypertension between contractions, fever, and a resting pulse above 120/min are not. Key point! When an item says to consider each finding alone, judge each value against its normal labor range rather than looking for a combined picture.