Risk Factors Of Preterm Birth In The Pregnant Women:a Meta-Study

Preterm birth (PTB) means a gestational age of less than 37+0 completed weeks of gestation (less than 259 days). The etiology of PTB is multifactorial and involves both genetic and environmental factors and so on. Infection is one of the causes of PTB. RCTs reported antibiotics treated pregnant women with the asymptomatic infection of the lower FGT (female genital tract) to reduce the incidence of preterm birth, the results were contradictory. To deal with the contradictory results above, we assessed whether the antibiotics would reduce the risk of preterm birth of pregnant women with the asymptomatic infection of the lower FGT by collecting the literature and performing a meta-analysis. We included a total of 16 literatures met the inclusion criteria (including 4952 cases and 4650 control cases), we also performed a meta-analysis on two subgroups:BV (bacterial vaginosis) and others (GBS, VVC, trichomoniasis vaginitis, UU, etc.), the results shows as follows:treatment did not reduce the risk of PTB (B V:OR = 0.85, CI= [0.63,1.15], P= 0.30; Others:OR= 0.96, CI= [0.65,1.41], P = 0.84); or the risk of PTB of pregnant women with a previous PTB (OR= 0.73, CI= [0.35,1.53], P= 0.40); or the risk of PPROM (BV:OR= 1.10, CI= [0.75,1.62], P= 0.63; Others:OR= 1.15, CI= [0.76,1.75], P= 0.51). However, early treatment may decrease the risk of PTB (Total:OR=0.46, CI= [0.25,0.83], P= 0.01; the BV:OR= 0.49, CI= [0.25,0.95], P= 0.03); treatment may decrease the risk of early PTB of pregnant women infected without BV(BV:OR= 1.14, CI= [0.76,1.70], P= 0.53; Others:OR= 0.62, CI= [0.39,0.98], P= 0.04); treatment may increase the risk of LBW of pregnant women infected without BV (BV:OR= 0.93, CI= [0.64,1.35], P =0.69; Others:OR= 1.39, CI= [1.06,1.83], P= 0.02). Meta-analysis results indicate that:antibiotic treatment for pregnant women with asymptomatic infection of the lower FGT did not decrease the risk of PTB. However, there is some suggestion that treatment before 22 weeks’ gestation may reduce the risk of PTB. Additional RCTs are needed to confirm these findings.Tumor necrosis factor-alpha (TNF-a) has been regarded as a candidate gene for preterm birth risk. However, studies to date have reported inconsistent findings for the association between TNF-a and preterm birth. The PubMed and CBM databases were systematically reviewed from January 1,1997 to December 31,2012. Sixteen studies concerning the association between preterm birth risk and the TNF-a-308G/A polymorphism were identified (including maternal genotype:1,813 cases and 3,125 controls; fetal genotype:592 cases and 1,785 controls) for the statistical test. The results reported here indicated that neither the maternal genotype (OR 1.04,95% CI 0.77-1.41, P=0.79) nor the fetal genotype (OR 0.65,95% CI 0.39-1.07, P=0.09) of-308G/A was associated with preterm birth susceptibility. Our meta-analysis demonstrates that the maternal-or fetal-polymorphism of TNF-α-308G/A were not associated with the preterm birth risk.