Birth weight and sex ratio after transfer at the blastocyst stage in humans.

OBJECTIVE

To analyze the birth weights and sex ratio of infants born after blastocyst transfer.

DESIGN

Retrospective analysis.

SETTING

Three infertility clinics.

PATIENT(S): Patients admitted for IVF with blastocyst transfer.

INTERVENTION

None.

MAIN OUTCOME MEASURE(S): Birth weights and sex ratio of infants born after blastocyst transfer.

RESULT(S): Statistically significantly more male infants were born after transfer of fresh blastocysts, either cocultured or cultured in sequential media. No specific differences in birth weight were observed between infants born after blastocyst transfer and those born after spontaneous conception.

CONCLUSION(S): More male infants than female infants were born after blastocyst transfer when transfers were performed as soon as the blastocyst stage was reached and male embryos had a faster cleavage rate.