Controlling oral infections is not considered part of prenatal care, though there is a link between gum disease and stillborn babies.
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BOSTON: The controversial link between oral infections during pregnancy and stillborn babies has been definitively proven by a team of American researchers.
Previous research has linked oral bacteria to premature births in humans and stillbirths in mice, however the often hypothesised link to stillbirths in humans has not been shown until now.
The scientists identified the bacteria responsible for a recent stillbirth in Santa Monica, California, as Fuscobacterium nucleatum. With careful DNA tests, they discovered the bacteria had originated the mother's mouth.
"It is the first documented case of this oral bacteria causing a full-term stillbirth in humans," said lead researcher Yiping Han, a microbiologist at Case Western Reserve University in Cleveland, Ohio. Her work appears in the February issue of the journal Obstetrics and Gynecology.
The effect of gingivitis
The researchers isolated the specific strain of bacteria F. nucleatum from the foetus, and then used it to create a DNA probe that could look for a bacterial match in the mother. Their tests showed the bacteria could only have originated in the mother's mouth.
The researchers said a variety of factors conspired toward the stillbirth. The mother, a 35-year-old in her first pregnancy, had experienced excessive gum bleeding, a symptom of pregnancy-associated gingivitis.
This gum bleeding, which affects about 75% of pregnant women, most likely allowed the oral bacteria to enter the mother's bloodstream. Normally, Han said, immune defences would step in, preventing the bacteria from reaching the placenta. This is key because the placenta lacks a strong immune system.
In this case, however, the mother's immune system was weakened because of an upper-respiratory tract infection. "It created a window of opportunity for the bacteria to escape the immune defence, reach the placenta and colonise," Han said.
Importance of oral health
Han's research team is trying to determine how often oral bacteria leads to a problem pregnancy; right now, scientists cannot say how many stillbirths stem from oral infections. However, Han said this study highlights the importance of oral hygiene for pregnant women, and recommended they alert a doctor about any gum bleeding.
John Novak, a periodontist at the University of Kentucky's Centre for Oral Health Research, agreed that more attention should be paid to oral health. He said while physicians work to control vaginal and other bodily infections in pregnant woman, the mouth is often overlooked.
"The control of oral infections … has not been considered as routine therapy either prior to conception or as part of prenatal care," he said.
David A Eschenbach, an obstetrician at the University of Washington, said the researchers' "careful DNA studies" had clearly linked F. nucleatum to the stillbirth, though he added that these events occur infrequently. Still, he said, "oral health is important anytime, especially during pregnancy.
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