As a result of IVF there are numerous spare eggs, and embryos. The ownership, and fate of these embryos is one of the major questions arising from the use of IVF. There are also many eggs that have been taken from women being sterilized, and increasingly they have donated the eggs for scientific research. These eggs are artificially fertilized to provide a large supply of human embryos in lab death camps (humans created in God's image) for scientific research as if they were not human.
I am aware of the practice. My question was, as a hypothetical, suppose that a woman were to agree to have fertilized only as many eggs at a time as she would be willing to have children, and proceeded to implant them all at such time as that was feasible (e.g. implant them two at a time, with as many nine-month pauses as turn out to be necessary). In such case I wouldn't think there'd be any "spare" embryos, at least not if the women upheld her commitment.