Freezing within 2 h from oocyte retrieval increases the efficiency of human oocyte cryopreservation when using a slow freezing/rapid thawing protocol with high sucrose concentration.

BACKGROUND: A number of factors influence the success of oocyte cryopreservation and subsequent ICSI. The aim of the present study is to establish the ideal time, after oocyte retrieval, for human oocyte cryopreservation via slow freezing/rapid thawing protocol with 0.3 M sucrose concentration in cryoprotectant solution (SF/RT 0.3 M). METHODS: Retrospective study with 75 patients on the clinical outcome of 93 oocyte thawing cycles divided into three groups. Group A: freezing within 2 h from oocyte retrieval. Group B: freezing between 2 and 3 h from retrieval. Group C: freezing after 3 h. RESULTS: The rate of best quality embryos was significantly higher (35.2%; P = 0.050) in Group A than in Group C (14.1%). Pregnancy and implantation rates were 39.1% (9/23) and 18.5% (10/54) in Group A. Nine clinical pregnancies per 124 thawed (7.3%) and 73 injected (12.3%) oocytes were observed in Group A versus 3 pregnancies per 174 thawed, 103 injected (1.7%, 2.9%, P = 0.046 and 0.0049) in Group B and 4 per 139 thawed, 88 injected (2.9%, 4.5%, NS) in Group C. The overall yield from oocytes cryopreserved within 2 h of retrieval was 8.1 implantations per 100 oocytes thawed. CONCLUSIONS: Embryo quality and clinical outcome of thawing cycles were significantly improved when oocyte cryopreservation by SF/RT 0.3 M was carried out within 2 h from oocyte retrieval.

Impact of medically assisted fertility on preterm birth.

Preterm birth is a frequent problem in women who undergo treatment for infertility. Many factors appear to contribute to the occurrence of this complication. Infertile women seem to have a predisposition to giving birth preterm and to having low birthweight babies. These complications also occur in women with a history of infertility who achieve pregnancy without treatment and who have singleton pregnancies. Assisted reproduction patients treated with in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI) have a disproportionately high occurrence of preterm births even with singleton pregnancies. Spontaneous preterm labour may be related to underlying medical conditions of the female partner, as its occurrence is not increased in subjects treated with ICSI (i.e. when the infertility problem is associated with male reproductive dysfunction in normal female partners). Multiple pregnancy is the factor most likely to be related to preterm birth in infertile women. The administration of drugs to induce ovulation either alone or combined with intrauterine insemination causes a significant increase in multiple pregnancies. The occurrence of higher order multiple pregnancy is also increased. Multiple pregnancy in women undergoing IVF or ICSI is related to the number of embryos transferred at the end of treatment. The transfer of more than two embryos in women under 35 is not associated with an increased chance of conception, while the occurrence of multiple pregnancy is significantly increased. Women over 40 may benefit from the transfer of more than two embryos, with fewer risks of multiple pregnancy. Single embryo transfer is increasingly considered a workable clinical option, particularly in young women. Hopefully, a more cautious approach to infertility management will reduce the occurrence of multiple pregnancy, spontaneous preterm labour and the high number of low birthweight infants born after treating these women.