National Infertility Group Report January 2013

Appendix I Single embryo transfer principles

The following principles underpin the advice which patients should receive about the appropriate number of embryos to transfer in a treatment cycle.

Embryo transfer principles in Scotland

Provider units are supportive of the need to address public health concerns of multiple pregnancies after IVF. A national strategy to reduce this figure in Scotland is required while at the same time maintaining overall live birth rates.

Several core principles should underpin the advice which patients receive from health care professionals about the appropriate number of embryos to transfer in a treatment cycle. These include:

1. Female age

• Embryo implantation rates fall with increasing female age. Units should therefore take account of female age in recommending the number of embryos to be transferred.

2. Previous pregnancies

• Women who have had a child in the past will have a higher chance of conception than those who are childless. This may influence the recommended number of embryos to transfer.

3. The number of good quality embryos available

• High numbers of good quality embryos are associated with higher implantation rates. In cycles where a sufficient number of good quality embryos are available for transfer Units should be mindful of the risk of multiple pregnancies after double embryo transfer.

4. The effectiveness of cryopreservation in the Unit

• A successful eSET policy is dependent on good survival and implantation rates after freeze/thaw of stored embryos. Decisions on ET numbers should take account of Unit specific data on embryo quality after cryopreservation.

5. The number and outcome of previous treatment cycles

• Women who have had successful treatment in the past will have higher success rates than those with previously unsuccessful treatment. This may influence the number of embryos to transfer.

6. Medical factors associated with obstetric risk

• Some patients have medical conditions which pose major risks to mother and baby if a multiple pregnancy occurs. Units must take account of obstetric factors in determining the number of embryos to transfer.

7. The source of the embryos to be transferred

• Patients in egg donation programmes may have higher implantation rates even at higher female age ranges. Single embryo transfer should be considered in these cases.

Monitoring progress of multiple births minimisation

Units are bound by national regulatory requirements in limiting the number of multiple births after assisted reproduction treatment. All Units have a multiple births minimisation strategy which outlines individual approaches to the issue. This encompasses elements of clinical and laboratory practice and communication with patients.

The outcome of licensed centres' individualised approaches to multiple births minimisation and Units' progress towards national regulatory targets are provided to the HFEA as a matter of course. Licensed centres should be accountable to those who fund NHS treatment and the Scottish Government should thus have access to similar data.