Sex ratio and birth weights of infants born as a result of blastocyst transfers compared with early cleavage stage embryo transfers.

OBJECTIVE: To analyze the birth weights and sex ratio of infants born as a result of blastocyst transfer and compare them with data resulting from the transfer of early-cleavage stage embryos.
DESIGN: Retrospective analysis.
SETTING: Monash IVF (private in vitro fertilization clinic). PATIENTS(S): One hundred twenty-five infertile patients who became pregnant after IVF procedures involving blastocyst transfer. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Sex ratio and birth weights of infants born after blastocyst transfer. RESULT(S): The sex ratio of 129.6 for infants born after blastocyst transfer was not significantly different from the sex ratio calculated from data compiled by NPSU for births resulting from early cleavage stage embryo transfers at Monash IVF (100.6) and all other assisted conception units in Australia and New Zealand (97.9). No differences were observed in the combined mean birth weight of male and female infants born as a result of blastocyst transfers and early-cleavage stage embryo transfers. CONCLUSION(S): There is no evidence of abnormal fetal growth or a shift in the sex ratio for infants born as a result of blastocyst transfer when compared with the case of births resulting from early cleavage stage embryo transfers within our unit or all other assisted conception units in Australia and New Zealand.