http://www.ncbi.nlm.nih.gov/pubmed/26081198
Hepatitis C

Huang QT, Huang Q, Zhong M, Wei SS, Luo W, Li F, Yu YH. Chronic hepatitis C virus infection is associated with increased risk of preterm birth: a meta-analysis of observational studies. J Viral Hepat. 2015 Dec; 22(12):1033-42.

Abstract
Although several epidemiological studies reported that maternal chronic hepatitis C virus (HCV) infection had significantly increased risk of undergoing adverse obstetrical and perinatal outcomes, studies on the relationship between HCV infection and risk of preterm birth (PTB) have yielded inconclusive and inconsistent results. Therefore, we conducted a meta-analysis to investigate the association between HCV infection and PTB. The electronic database was searched until 1 September 2014. Relevant studies reporting the association between HCV infection and the risk of PTB were included for further evaluation. Statistical analysis was performed using revmen 5.3 and stata 10.0. Nine studies involving 4186698 participants and 5218 HCV infection cases were included. A significant association between HCV infection and PTB was observed (odds ratio = 1.62, 95% CI 1.48-1.76, P < 0.001, fixed-effects model). Stratification according to maternal smoking/alcohol abuse, maternal drug abuse or coinfected with HBV and/or HIV matched groups still demonstrated that women with HCV infection had a high risk for PTB. Findings from our meta-analysis suggested that maternal HCV infection was significantly associated with an increased risk of PTB. In the future, pathophysiological studies are warranted to ascertain the causality and explore the possible biological mechanisms involved.