The elective single embryo transfer policy is the only effective strategy known to minimize the risk of multiple pregnancy. However, little is known about its applicability to women older than 35 years.
Veleva, Z., Vilska, S., Hyden-Granskog, C., Tiitinen, A., Tapanainen, J. S., & Martikainen, H. (2006). Elective single embryo transfer in women aged 36-39 years. Hum. Reprod., 21(8), 2098–2102. https://doi.org/10.1093/humrep/del137