FLIP-2 Live Biotherapeutics to Prevent Preterm Birth
Research type
Research Study
Full title
FLIP-2: A placebo-controlled double blinded randomised trial to assess the safety and efficacy of LACTIN-V, a live biotherapeutic Lactobacillus crispatus strain CTV-05, in reducing the risk of preterm labour in a cohort of women predefined as at high risk.
IRAS ID
1010339
Contact name
Lynne Sykes
Contact email
Sponsor organisation
Imperial College London
ISRCTN Number
ISRCTN13610566
Research summary
Spontaneous preterm birth occurs when a mother goes into labour before 37 weeks. Early preterm birth (babies born before 34 weeks) is an important cause of the death of newborn babies, and long-term disability in some of those who survive. There is now good evidence that the type of bacteria in the mother's vagina during pregnancy can affect the risk of preterm birth. The presence of lactobacilli (except for one particular type; lactobacillus iners) helps protect against early birth. The type lactobacillus crispatus, in particular, is linked to the lowest risk of preterm birth. On the other hand, having lactobacillus iners or no lactobacilli at all increases the risk of preterm birth.
We have found that vaginal administration of a strain of lactobacillus crispatus (called CTV-05) using during pregnancy leads to growth of this bacteria in the vagina, and in most cases replacing lactobacillus iners or other bacteria present in the vagina. The new lactobacillus crispatus will remain present for the whole of the pregnancy.
In this study, we will determine whether administration of lactobacillus crispatus CTV-05 will reduce the risk of preterm birth. We will recruit a group of women who have been predefined as at high risk because they had a previous preterm birth or previous second trimester loss. These are women who are seen in preterm birth prevention clinics in NHS hospitals. They will be randomised to being given either vaginal CTV-05 or an identical inactive substance (placebo) during their pregnancy. Our main outcome will be to determine the rates of preterm birth in the two groups. However, we will also take vaginal swab samples and blood tests to look at the effect of CTV-05 or placebo on the bacteria present within the vagina and how that links to the risk of preterm birth. We anticipate that the study will take up to 3 years to recruit all of the participants from four hospitals in London, and for all of their pregnancy outcomes to become known.
REC name
London - Harrow Research Ethics Committee
REC reference
25/LO/0766
Date of REC Opinion
5 Dec 2025
REC opinion
Further Information Favourable Opinion