Natural-cycle in vitro fertilization in poor responder patients: a survey of 500 consecutive cycles.

Objective: To determine the role of the natural cycle for in vitro fertilization (IVF) in poor responder patients.

Design: Retrospective survey.

Setting: Private center for assisted reproduction.

Cetrorelix protocol versus gonadotropin-releasing hormone analog suppression long protocol for superovulation in intracytoplasmic sperm injection patients older than 40.

Objective: To determine which protocols work better between cetrorelix and long protocols in older patients in a randomized controlled study.

Design: A controlled randomized study in a single private IVF center.

Setting: Infertile women referred to a private IVF center.

Use of a medium buffered with N-hydroxyethylpiperazine-N-ethanesulfonate (HEPES) in intracytoplasmic sperm injection procedures is detrimental to the outcome of in vitro fertilization.

Objective: This study was conducted to determine whether N-hydroxyethylpiperazine-N-ethanesulfonate (HEPES)-buffered medium used for the microinjection of sperm into oocytes may be detrimental for the embryo.

Design: Controlled randomized study.

Setting: Private IVF center.

Number of embryos transferred and implantation.

Multiple pregnancies are considered the most frequent and serious complication of assisted reproduction technology. To reduce the frequency of multiple pregnancies, several centers have adopted a policy of reducing the number of embryos transferred in the uterus, suggesting single embryo transfer. Even though a significant number of papers have been published on this issue, no general consensus exists on how many embryos to replace in the uterus and at which cleavage stage.