Human embryo co-culture: results of a randomized prospective study.

Objective: To evaluate in vitro culture of human embryos in the presence or absence of a Vero cell monolayer.

Design: Randomized prospective analysis.

Patients: Seventy-five couples were randomly allocated to either an experimental study group (embryos in co-culture) or a control group.

Results: A significantly higher cleavage rate (92%) was obtained in the co-culture group compared with the control group (83%). In addition, a higher percentage of morphologically superior embryos was observed in the co-culture group than in the control group, although no significant difference was found between the two groups in blastocyst development or clinical outcome.

Conclusions: When taking final clinical results into consideration in a routine IVF program, the conventional method provides more practicality and efficiency if transfers are performed on either day 2 or 3. However, if embryos remain in culture, co-culture systems allow for replacements or cryopreservation at the blastocyst stage.