There seems to be a general consensus on the supplementation of progesterone (P4) for luteal phase support (LPS) to all women after in vitro fertilization (IVF) treatment. However, there is no agreement about the precise duration of LPS.

The objective of the study is to investigate the effect of early cessation of progesterone for LPS after IVF treatment on the pregnancy outcome, with special interest in determining the miscarriage rate and episodes of bleeding between the date of the first ultrasound (US) and up to 12 weeks of gestation.

Patients start to receive 200 mg twice a day of P4 on the day after oocyte retrieval.

All patients which show a gestational sac in their uterus in the first US are included in this study and randomized.

Inclusion criteria:

1. Patients who underwent ovarian stimulation using GnRH analogues,
2. Fresh embryo transfer,
3. LPS by vaginal micronized P4,
4. Clinical pregnancy demonstrated by US and
5. Informed consent signed.

Exclusion criteria:

Patients who had bleeding episodes before their first US because they are likely to continue P4 therapy without medical indication.

Inclusion Criteria:

1. Patients who underwent ovarian stimulation using GnRH analogues,
2. Fresh embryo transfer,
3. LPS by vaginal micronized P4,
4. Clinical pregnancy demonstrated by US and
5. Informed consent signed.

Exclusion Criteria:

Patients who had bleeding episodes before their first US because they are likely to continue P4 therapy without medical indication.

Women