The role of infection in miscarriage

Abstract

BACKGROUNDMiscarriage is the spontaneous loss of a pregnancy before 12 weeks (early miscarriage) or from 12 to 24 weeks (late miscarriage) of gestation. Miscarriage occurs in one in five pregnancies and can have considerable physiological and psychological implications for the patient. It is also associated with significant health care costs. There is evidence that potentially preventable infections may account for up to 15% of early miscarriages and up to 66% of late miscarriages. However, the provision of associated screening and management algorithms is inconsistent for newly pregnant women. Here, we review recent population-based studies on infections that have been shown to be associated with miscarriage.METHODSOur aim was to examine where the current scientific focus lies with regards to the role of infection in miscarriage. Papers dating from June 2009 with key words ‘miscarriage’ and ‘infection’ or ‘infections’ were identified in PubMed (292 and 327 papers, respectively, on 2 June 2014). Relevant human studies (meta-analyses, case–control studies, cohort studies or case series) were included. Single case reports were excluded. The studies were scored based on the Newcastle – Ottawa Quality Assessment Scale.RESULTSThe association of systemic infections with malaria, brucellosis, cytomegalovirus and human immunodeficiency virus, dengue fever, influenza virus and of vaginal infection with bacterial vaginosis, with increased risk of miscarriage has been demonstrated. Q fever, adeno-associated virus, Bocavirus, Hepatitis C and Mycoplasma genitalium infections do not appear to affect pregnancy outcome. The effects of Chlamydia trachomatis, Toxoplasma gondii, human papillomavirus, herpes simplex virus, parvovirus B19, Hepatitis B and polyomavirus BK infections remain controversial, as some studies indicate increased miscarriage risk and others show no increased risk. The latest data on rubella and syphilis indicate increased antenatal screening worldwide and a decrease in the frequency of their reported associations with pregnancy failure. Though various pathogens have been associated with miscarriage, the mechanism(s) of infection-induced miscarriage are not yet fully elucidated.CONCLUSIONSFurther research is required to clarify whether certain infections do increase miscarriage risk and whether screening of newly pregnant women for treatable infections would improve reproductive outcomes.

Current views on vaginal microbiota and its impact on pregnancy outcomes

“…Установлено, что наличие лактобацилл, продуцирующих высокий уровень перекиси водорода, ассоциировано с низкой частотой БВ, преждевременных родов и послеродовых инфек ционных осложнений [10,11]. Изучение генотипических и биохимических свойств ваги-нальных лактобацилл показало, что L. crispatus, L. jensenii и L. vaginalis представляют собой наиболее часто встречающиеся виды перекиси продуцирующих лактобацилл [12].…”

Human Brucellosis and Adverse Pregnancy Outcomes

“…Studies conducted over the last 30 years have demonstrated a correlation between an increased rate of adverse pregnancy outcomes with infection by certain microbial agents [70]. Historical, experimental, and epidemiological evidence supports the concept that Brucella infection in animals is a significant risk factor for abortion [19, 21•, 22].…”

Local immunity status in patients with miscarriages and herpetic infection

“…It is believed that potentially preventable infections can account for up to 15% of early miscarriages, and for up to 66% of late miscarriages. And, chronic persistent endometritis coexists with every third pregnancy and is detected in more than 60% of cases of recurrent miscarriage [2].…”