DUMBEST thing ever said!
Embryo is a product of conception. No conception=no embryo. Or are they actually saying an "embryo" is lost every time a woman has a period?
An egg is fertilized and becomes an embryo several days before implantation (implantation being the medical definition of conception). If an egg is fertilized too late, it won't be viable, and either won't implant or will simply fail to keep dividing. Eggs can fertilize slightly before or after the point where they're at the right stage of "ripeness" to form a viable embryo; if that happens, they form a non-viable embryo instead. This guy is nuts enough to worry about this.