White blood cells in pregnancy: reference intervals for before and after delivery

Abstract

Background White blood cells (WBC) are commonly measured to investigate suspected infection and inflammation in pregnant women, but the pregnancy-specific reference interval is variably reported, increasing diagnostic uncertainty in this high-risk population. It is essential that clinicians can interpret WBC results in the context of normal pregnant physiology, given the huge global burden of infection on maternal mortality. Methods We performed a longitudinal, repeated measures population study of 24,318 pregnant women in Oxford, UK, to map the trajectory of WBC between 8-40 weeks of gestation. We defined 95% reference intervals (RI) for total WBC, neutrophils, lymphocytes, eosinophils, basophils, and monocytes for the antenatal and postnatal periods. Findings WBC were measured 80,637 times over five years. The upper reference limit for total WBC was elevated by 36% in pregnancy (RI 5.7-15.0×10 9 /L), driven by a 55% increase in neutrophils (3.7-11.6×10 9 /L) and 38% increase in monocytes (0.3-1.1×10 9 /L), which remained stable between 8-40 weeks. Lymphocytes were reduced by 36% (1.0-2.9×10 9 /L), while eosinophils and basophils were unchanged. Total WBC was elevated significantly further from the first day after birth (similar regardless of the mode of delivery), which resolved to pre-delivery levels by an average of seven days, and to pre-pregnancy levels by day 21. Interpretation There are marked changes in WBC in pregnancy, with substantial differences between cell subtypes. WBC are measured frequently in pregnant women in obstetric and non-obstetric settings, and results should be interpreted using a pregnancy-specific RI until delivery, and between days 7-21 after childbirth. Funding None.

Reference intervals for clinical biochemistry and haematology tests during normal pregnancy

“…The haematological trimester-specific-RIs for RBC, WCC, Hb, Hct, platelet count and neutrophils were strongly in agreement with those reported by Markus et al 49 The decrease in Hb which is often referred to as ‘physiologic anaemia’ of pregnancy and decrease in Hct are common phenomena observed in pregnant women and have been previously reported. 4,50 The elevation of WCC and neutrophils in all trimesters is consistent with Dockree et al 51 The WCC is frequently measured when there is suspicion of infection; thus, it is imperative that WCC results are interpreted in the context of normal pregnancy. Furthermore, it is critical to appreciate the influence of ethnicity on haematological parameters.…”

Common hematological parameters reference intervals for apparently healthy pregnant and non-pregnant women of South Wollo Zone, Amhara Regional State, Northeast Ethiopia

“…The total WBC count upper RI limit in this study was greater than previous reports from Ethiopia [26,38] and Central Uganda [40], but it was equivalent to a study conducted in Northwest Morocco [41]. Moreover, the RI of total WBC count was lower than study done in United Kingdom [43]. The lower reference limit of Lymph%, MID% and Gran% among pregnant women of this study was lower than Addis Ababa [38] and Central Uganda [40], but the upper reference limit was higher than a study done in Addis Ababa, Central Uganda and Northwest Morocco [38,40,41].…”

Rescue Cervical Cerclage for Protruding Amniotic Sac: A Retrospective Analysis of Clinical Efficacy

“…Leukocytosis is an obvious indicator of active infection, and it has been associated with a failure to prolong pregnancy in previous reports [11,[15][16][17]. In addition, white blood cell count is also influenced by pregnancy itself [18,19], and a correlation between the number of leukocytes and ongoing labor course has been reported [20]. At what level white blood cell count is predictive of futile cerclage remains unknown, and further investigations are needed to clarify this issue.…”