Preimplantation embryo development in vitro is poorer and results in decreased implantation rates compared to those developed in vivo. A contributing factor to these problems in vitro may be the lack of maternally derived growth factors, such as insulin-like growth factor binding protein-3 (IGFBP3) (1-2). Exogenous IGFBP3 improves mouse preimplantation embryo development by increasing cell division rate between the 2-cell and 8-cell stage, blastocyst formation and hatching (3-4). IGFBP3 can act via insulin-like growth factor-independent mechanisms, such as via the sphingosine-1-phosphate (S1P) signalling pathway (5) and this may occur in mouse embryos to promote preimplantation embryo development (3-4) and implantation. In this study, embryos were exposed to IGFBP3 during preimplantation development and to IGFBP3 and/or S1P at the embryonic-maternal interface during implantation. Two measures of implantation were assessed; attachment where blastocysts were co-cultured with Ishikawa cells, a receptive human endometrial adenocarcinoma cell line for 48 h, and invasion where blastocysts were transferred to coverslips for outgrowth for 96 h. Exposure to IGFBP3 during preimplantation embryo development improved blastocyst attachment but had no effect on outgrowth. Exposure to IGFBP3 only during the implantation process reduced blastocyst outgrowth area and had no effect on attachment. Exposure to S1P during implantation had no effect on blastocyst attachment or outgrowth and did not prevent the reduced outgrowth caused by IGFBP3. In conclusion, adding IGFBP3, only during implantation, is not beneficial but it improves attachment when added to embryo culture medium during preimplantation development, and thus should be considered as a media component to improve the outcomes of assisted reproductive technologies.