Preterm birth is a common problem in obstetric care,with estimates ranging from 5% in several European countries to 18% in some African countries, Preterm labor defined as delivery before 37 completed weeks is the leading cause of perinatal and neonatal morbidity and mortality and strongly related to the developmental and neurological disabilities later in life..

There is still considerable uncertainty regarding the optimal progesterone type, route of administration, dosage and timing of start of therapy to prevent preterm labor in risky women

This study aims to compare between the efficacy of intramuscular 17alpha-hydroxyprogestrone, progesterone vaginal suppositories and dydrogesterone oral tablets in prevention of preterm labor in high risk women.

All women will be counseled regarding mode of intervention and informed consent will be obtained. All cases will be subjected to complete history taking, routine antenatal examination and investigations, treatment of genital or urinary tract infections if diagnosed. Routine obstetric ultrasound examination and measurement of cervical length by transvaginal ultrasound will be carried out at 16-18weeks of pregnancy.

The study population will be randomly distributed according to the mode of intervention into 3 groups.

Randomization is performed using a Computer-generated randomization system. Blinding of the intervention is not feasible in this trial (owing to the different route of administration of the studied drugs).Table of randomization is obtained

Group 1:

Women who will take intramuscular 17 alpha hydroxyprogestrone caproate

Dose:

250 mg intramuscularly, once weekly starting from 16 weeks till delivery or 36 weeks.

Group 2 :

Women who will take progesterone 200mg vaginal suppositories.

Dose:

Once per day starting from 16 weeks till delivery or 36 weeks

Group 3 :

Women who will take oral dydrogesterone

Dose:

Take 2 tablets a day starting from 16 weeks till delivery or 36 weeks

Color Doppler blood flow velocity examination of fetal circulation will be performed by an independent investigator blinded to treatment before treatment &after two weeks of treatment.

Inclusion Criteria:

• Singleton pregnancy

• Living fetus with gestational age 16-18weeks (calculated according to date of last menstrual period confirmed with earlier ultrasound examination).

• Presence of risk factor for preterm labor:

  1. Previous spontaneous preterm labor in previous singleton Pregnancy, OR
  2. Previous spontaneous second trimestric miscarriage less than 3 times, OR
  3. Short cervix less than 25mm diagnosed during midtrimesteric transvaginal ultrasound examination at 16-18 weeks with or without history of previous preterm labor.

Exclusion Criteria:

• Multiple pregnancy.

• Medical or obstetric conditions requiring termination of pregnancy

• Contraindication to progesterone administration or its use earlier in this pregnancy

  • Current or past history of thrombophlebitis, thromboembolic disorders, or cerebral apoplexy.
  • Liver dysfunction or disease.
  • Known or suspected malignancy of breast or genital organs.
  • Undiagnosed vaginal bleeding.
  • Missed abortion.
  • Known sensitivity to progesterone injection.
  • Known sensitivity to sesame oil/seeds.

• Congenital fetal anomalies

• Cervical cerclage in the current pregnancy.

• Presence of uterine anomalies (Unicornuate uterus , Uterus didelphys, bicornuate uterus,Septated uterus) or uterine fibroid.

• Presence of history of chronic hypertetion, chronic liver or kidney diseases, and pregnancy induced hypertension.