Impact of elevated first and second trimester white blood cells on prevalence of late-onset preeclampsia

OBJECTIVE: Increased white blood cell count (WBC) is known to be associated with preeclampsia (PE). This study aimed to determine whether WBC count >10×10(9)/L had significant impact on late-onset PE (LOPE) during the first and second trimesters. METHODS: This prospective study was conducted in 600 pregnant women from Shanghai Pudong Hospital in China from July 2019 to August 2020. They were classified into four groups: Group 1: WBC count ≤10×10(9)/L at 10th–12th week and 24th–26th week; Group 2, WBC count ≤10×10(9)/L at 10th–12th week but WBC count >10×10(9)/L at 24th–26th week; Group 3, WBC count >10×10(9)/L at 10th–12th week but WBC count≤10×10(9)/L at 24th–26th week; Group 4, WBC count >10×10(9)/L at 10th–12th week and 24th–26th week. Complete blood count results from 10th–12th week and 24th–26th week were obtained for each patient. Maternal laboratory values including white blood cell (WBC) count were compared between the four groups. RESULTS: 34 women were diagnosed with LOPE at predelivery. The estimated incidence rate of LOPE during pregnancy was 3.6% in Group 1, 5.8% in Group 2, 7.2% in Group 3, and 11% in Group 4 for the respective WBC level of Group 1, 2, 3 and 4. After adjusting for potential influencing factors of PE, the respective relative risks for LOPE was 1.0 (reference), 1.76 (95% CI 0.37, 8.30), 2.23 (0.85, 5.89), and 3.07 (1.34, 7.02) (P for trend = 0.048). CONCLUSIONS: Our results demonstrated that WBC count >10×10(9)/L during the first and second trimesters is a risk of LOPE.