Microbiome of the Placenta and Healthy Pregnancies

Contributed by Azarene Foutouhi

Very little is known at this time of the mechanisms and interactions between the fetal and maternal systems and their resultant effects on the health a pregnancy. While some research has indicated complex relationships between the role of fetal placental stem cells and the hormones they produce from maternally derived compounds in the maintenance of a pregnancy, there is yet little information regarding the pathways and parties responsible when things go wrong. Recently, interest in describing the microbiome of the placenta in a healthy pregnancy has led to questions on the potential involvement of bacteria in placental health, namely spontaneous abortion and preterm birth.

More specifically, research has linked certain strains of bacteria responsible for periodontal disease, an infectious disease of various severity affecting the majority of individuals, to premature and term stillbirths. One such bacteria associated with periodontal disease, Fusobacterium nucleatum, is a gram negative anaerobic bacteria with superior adhesion capabilities that is found in the amniotic fluid of 30% of women in preterm labor. These levels greatly outnumber any other bacteria present.

While it has previously been supposed that any bacteria found in the placenta or amniotic fluid is a result of infection from an ascending route through the cervix, this particular species of Fusobacterium differs from those isolated from the lower genital tract, suggesting its presence in amniotic fluid is due to hematogenic transfer from the mother to the fetus through the placenta. By describing a normal placental microbiome and detailing the interactions between host and microbe, we will be better able to explore the potential effect of bacteria on the maintenance of pregnancy and in the development of the fetus, as well as any indications of their effects on the long term health of the child.

Yiping W. Han. 2004 April. Fusobacterium nucleatum Induces Premature and Term Stillbirths in Pregnant Mice: Implication of Oral Bacteria in Preterm Birth. Infection and Immunity. 72(4): 2272-2279

Yiping W. Han. 2000 June. Interactions between Periodontal Bacteria and Human Oral Epithelial Cells: Fusobacterium nucleatum Adheres to and Invades Epithelial Cells. Infection and Immunity. 68(6):3140-3146.

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