Is the Vaginal Microbiome and Metabolome Associated With Spontaneous Preterm Birth (sPTB) in Multiple Pregnancies?

The aim of this study is to try and find links between the microscopic organisms (such as bacteria, yeasts and viruses) in the vagina, and twin pregnancies that deliver too early (preterm birth). Being born earlier than expected (preterm birth) happens in over half of twin pregnancies with 1 in 10 sets of twins delivering before 32 weeks gestation. Sometimes, when birth happens very early, babies can be at risk of serious harm including damage to the brain, lungs and bowel - all of which can result in life changing disabilities. How severe these problems are is related to how early they are born. Unfortunately, tests used to find women at risk of preterm birth have only been proven to work when the woman is carrying one baby, not twins, and at present no treatment has been shown to be effective in stopping a twin pregnancy from delivering early. Preventing twins from being born too early is therefore a target for research by the NHS and patient groups including the James Lind Alliance. It is normal for every woman to have microscopic organisms (such as bacteria, yeasts and viruses) in the vagina. New interest has been shown at looking closely at these organisms during pregnancy. These organisms can change and may be related to the number of weeks a woman will go into labour, however to date all research on this has been conducted in pregnancies with only one baby. We want to explore these organisms in twin pregnancies; taking swabs from the vagina at 16- and 28-weeks of your pregnancy, along with at the time of birth. Information will be gathered on the organisms present in the vagina (both of women that deliver too early and those that deliver on time), hoping this information will help us understand why preterm birth happens and help predict the chances of preterm labour in twin pregnancies. By identifying specific organisms linked with preterm birth, we also hope to be able to guide new targets for treatments to prevent preterm birth in twins in future. Due to the small number of twin pregnancies, measurements of how 'stiff' the neck of the womb (cervix) are along with blood samples will be taken. Research has shown that there may be links with how stiff the neck of the womb is and premature birth as well as markers within the blood that may help us predict preterm birth that are yet to be discovered. This will provide the foundations for a future research study.

Inclusion Criteria: * Age ≥18 years * Twin pregnancy * Able to provide informed consent Exclusion Criteria: * Known or suspected severe structural/chromosomal fetal abnormality * Non-English speaking