Abstract: A pessary for the prevention of preterm birth, and in particular two pathological conditions of pregnancy known as isthmico-cervical incontinence and cervical shortening, both of which are associated with increased risks for pregnancy loss and/or premature deliveries of babies. The pessary includes a sleeve supported within a ring by an annular member. The sleeve is intended to contact the cervix and maximize the length of the cervix while the annular member and ring contact the vagina. The pessary may be fabricated from a pliable medical-grade silicon, and the pessary may include one or more sensors to measure various patient parameters indicative of a premature cervical contraction.