The included women will be randomly allocated to prophylactically receive either vaginal progesterone at a dose of 200 mg (prontogest 200mg every 12 hr) combined with oral aspirin at a dose of 100mg once daily both at the same time (group1), or vaginal progesterone (prontogest 200mg every 12 hr) and oral placebo (manufactured in a standard way to have the same size and shape of asprin tablet) also at the same time (group 2).
This is a double blinded randomized placebo controlled clinical trial to detect the efficacy and safety of vaginal progesterone alone or combined with aspirin in prevention of recurrent PTB.