@floppy Yes, it is less likely to be viable for several reasons: 1) It is much more likely to be ectopic, and all ectopic pregnancies are not viable 2) The IUD must be removed, and the removal process may interfere with the implanted embryo 3) The IUD may have already interfered with the implantation process, causing a structurally weak connection which may not support further cell division.
There may be other reasons but those are just off the top of my head. Even seemingly viable embryos which implanted in spite of the IUD have a higher miscarriage rate compared to non-IUD pregnancies.
There may be other reasons but those are just off the top of my head. Even seemingly viable embryos which implanted in spite of the IUD have a higher miscarriage rate compared to non-IUD pregnancies.