Premature births linked to changes in mother's bacteria

Changes to the communities of microbes living in the reproductive tract of pregnant women could help to spot women at risk of giving birth prematurely, according to Imperial College London researchers.

A study of hundreds of women, carried out at Imperial College London, found that subtle changes to the bacteria present in the vagina were strongly associated with the mother's waters breaking early and preterm birth -- the baby being born before 37 weeks.

According to the researchers, the findings show that a shift away from the usual healthy balance of vaginal bacteria was associated with waters breaking early, and could have an impact on the health of mother and baby, including increasing the risk of sepsis for newborns.

Samples were collected from a prospective group of 250 pregnant women with and without risk factors for giving birth prematurely -- such as having a history of preterm birth or miscarriage -- of which 27 did in fact have a premature birth. They also collected samples from a second, smaller group of 87 women who presented to hospital with premature membrane rupture. All patients were seen at Queen Charlotte's and Chelsea Hospital and Chelsea and Westminster Hospital.

Previous research has shown that over the course of pregnancy the bacteria that colonise the vagina become less diverse and are dominated chiefly by Lactobacillus species, the same type of bacteria found elsewhere in the body including the gut and mouth.

Analysis of the team's samples revealed that premature membrane rupture was associated with a shift in microbiota, with a drop in Lactobacillus and an increase in other types of bacteria, including potentially harmful bugs such as Staphylococcus and Streptococcus.

The team also analysed samples from the small group of women with premature rupture before and after the preventative antibiotic treatment -- oral erythromycin, four times a day for 10 days. Swabs were taken before treatment and then at 48 hours, one week and two weeks.

For those women whose microbial makeup was dominated by Lactobacillus before the treatment, the antibiotics resulted in a decline in Lactobacillus and a greater diversity of bugs. However, in those women with reduced Lactobacillus to begin with, the treatment was beneficial in some, reducing the amount of potentially harmful bacteria as well.

See:

Richard G. Brown, Julian R. Marchesi, Yun S. Lee, Ann Smith, Benjamin Lehne, Lindsay M. Kindinger, Vasso Terzidou, Elaine Holmes, Jeremy K. Nicholson, Phillip R. Bennett, David A. MacIntyre. Vaginal dysbiosis increases risk of preterm fetal membrane rupture, neonatal sepsis and is exacerbated by erythromycin. BMC Medicine, 2018; 16 (1) DOI: 10.1186/s12916-017-0999-x

Posted by Dr. Tim Sandle