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.

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).

Inclusion Criteria:

1. Women of any age
2. Any parity
3. Healthy singleton pregnancy
4. History suggestive of one or more previous PTB
5. Current pregnancy (16-20) weeks gestation.

Exclusion Criteria:

1. Multifetal pregnancy.
2. History of ante partum PROM.
3. Cervical Incompetence or current cervical cerclage.
4. Known fetal anomaly.
5. Hypertension requiring medications.
6. History of Thrombo-embolic disorders.
7. Known allergy to progesterone or asprin.
8. Known liver disease.
9. Established preterm labor
10. Short cervix

All participants and investigators