Prevention of multiple pregnancies; the Belgian project

When no choice of embryos exists, the multiple pregnancy risk is still high

Multiple pregnancies arising from assisted reproduction are known to be associated with increased medical, psychological, economical and social risks. If only two embryos develop after culture, how should the couple be counselled in relation to the risk of multiple pregnancy? We performed a retrospective review of all IVF/ICSI treatments performed between 1 January 2005 and 31 December 2007, that resulted in double embryos transfer (DET). We identified 623 cycles with a fortuitous DET (Group I) and 635 cycles with an elective DET (Group II). Group II were significantly more likely to have twins when compared with Group I, irrespective of age. Twin rates in Group I were higher in IVF compared with ICSI; 33.3% vs 16.6% in < 35 years old and 16.2% vs 7.6% in 35-40 years old. Therefore, single embryo transfer should be considered for IVF patients below 35 years old, even if only two good quality embryos are available.

In unselected patients, elective single embryo transfer prevents all multiples, but results in significantly lower pregnancy rates compared with double embryo transfer: a randomized controlled trial

BACKGROUND

Elective single embryo transfer (eSET) in a selected group of patients (i.e. young patients with at least one good quality embryo) reduces the number of multiple pregnancies in an IVF programme. However, the reduced overall multiple pregnancy rate (PR) is still unacceptably high. Therefore, a randomized controlled trial (RCT) was conducted comparing eSET and double embryo transfer (DET) in an unselected group of patients (i.e. irrespective of the woman's age or embryo quality).

METHODS

Consenting unselected patients were randomized between eSET (RCT-eSET) (n = 154) or DET (RCT-DET) (n = 154). Randomization was performed just prior to the first embryo transfer, provided that at least two 2PN zygotes were available. Non-participants received our standard transfer policy [SP-eSET in a selected group of patients (n = 100), otherwise SP-DET (n = 122)].

RESULTS

The ongoing PR after RCT-eSET was significantly lower as compared with RCT-DET (21.4 versus 40.3%) and the twin PR was reduced from 21.0% after RCT-DET to 0% after RCT-eSET. The ongoing PRs after SP-eSET and SP-DET did not differ significantly (33.0 versus 30.3%), with an overall twin PR of 12.9%.

CONCLUSION

To avoid twin pregnancies resulting from an IVF treatment, eSET should be applied in all patients. The consequence would be a halving of the ongoing PR as compared with applying a DET policy in all patients. The transfer of one embryo in a selected group of good prognosis patients leads to a less drastic reduction in PR but maintains a twin PR of 12.9%.

Elective single embryo transfer (eSET) policy in the first three IVF/ICSI treatment cycles

BACKGROUND

Elective single embryo transfer (eSET), applied in the first or second IVF cycle in young patients with good quality embryos, has been demonstrated to lower the twin pregnancy rate, while the overall pregnancy rate is not compromised. It is as yet unclear whether eSET could be the preferred transfer policy in all treatment cycles, or that it should be restricted to the first or first two cycles.

METHODS

eSET policy (when two or more embryos were available, at least one of them being of good quality) was offered to patients younger than 38 years in the first three treatment cycles. Retrospectively, treatment cycle outcome was studied.

RESULTS

In 326 patients, 586 treatment cycles were performed (326 first, 168 second and 92 third treatment cycles). In 65 cycles (11%), eSET could not be applied because there was either no fertilization, or only one embryo available. In the remaining 521 cycles, eSET was performed in 111 cycles (19%), while in 410 cycles, no good quality embryo was available resulting in the transfer of two embryos (double embryo transfer, DET). No significant differences in ongoing pregnancy rates after transfer of fresh embryos were observed between eSET and DET in the first (both 33%), second (36 and 23%, respectively) and third treatment cycles (20 and 24%, respectively). In significantly more eSET cycles compared to DET cycles, could embryos be frozen. This resulted in a significantly higher cumulative pregnancy rate after eSET compared to DET.

CONCLUSIONS

In patients younger than 38 years with at least one top quality embryo, eSET can be the transfer policy of choice in at least the first three treatment cycles, since the pregnancy rates obtained in each treatment cycle are comparable to those after DET.