Elevated C-reactive protein and complement C3 levels are associated with preterm birth: a nested case-control study in Chinese women.

BACKGROUND: Currently, there are many studies researched the associations between maternal serum inflammatory indicators (i.e. ferritin, C-reactive protein [CRP], C3 and C4) and preterm birth (PTB). The results, however, are inconsistent. Therefore, the aim of this study was to estimate the relationship between maternal serum inflammatory indicators and PTB in a nested case-control (NCC)study. METHODS: A NCC study was conducted by Guangxi Birth Cohort Study which enrolled a total of 6203 pregnant women between 5(0/7) and 34(6/7) weeks of gestational age (wGA) from six cities in China between 2015 and 2016. There were 206women who delivered preterm ( 16.60 mg/L) are related to the risk of PTB (OR = 2.16, 95% CI: 1.02-4.56, p = 0.044) in the first trimester. The association of C3 was extremely related to those who delivered PTB (OR = 2.53, 95% CI: 1.14-5.64, p = 0.023) in the first trimester. Moreover, no significant associations were found in C4 (p = 0.079) and ferritin (p = 0.067) between PTB. CONCLUSIONS: Elevated concentrations of CRP and C3 in the first trimester were associated with increased risk of PTB. Inflammatory indicators may act a pivotal part in early diagnosis and prognosis of PTB.