Although it is known that corticosteroid administration causes leukocytosis, the magnitude and length of time this leukocytosis persists is unknown during pregnancy. This study aimed to establish the expected range of maternal leukocytosis in healthy pregnant women at risk for preterm delivery after antenatal corticosteroid administration. PubMed, Embase and ClinicalTrials.gov were searched to identify the studies in healthy women at risk for preterm delivery without signs of clinical infection that reported white blood cell values preceding and after antenatal corticosteroid administration. The inverse variance weighting technique was used to calculate the weighted means and the standard deviation from the mean for each time period. Six studies met inclusion criteria and included 524 patients and 1406 observations. Mean ± standard deviation maternal white blood cell count values prior to antenatal corticosteroid administration and up to 24, 48, 72 and 96 hours after corticosteroid administration were 10.4 ± 2.4, 13.6 ± 3.6, 12.1 ± 3.0, 11.5 ± 2.9 and 11.1 ± 2.5 × 109/L, respectively. Leukocytosis in healthy, non-infected women is expected to peak 24 hours after antenatal corticosteroid administration and the magnitude of increase is small. Impact statement What is already known on this subject: While it is well known that administration of antenatal corticosteroids causes leukocytosis, it is currently unknown the magnitude and length of time the leukocytosis persists. What the results of this study add: This study establishes the expected range and the temporal progression and regression with antenatal corticosteroid administration in healthy pregnant women at risk for preterm delivery without clinical signs of infection. What the implications are of these findings for clinical practice and/or further research: Clinicians may wish to consider further investigation into the clinical cause, whether infectious or non-infectious, for absolute values and changes outside this range.
Keywords: Prenatal care; corticosteroids; leukocyte count; leukocytosis; pregnancy; steroids.