Fair enough. You've answered my question, so I'll answer yours.
If we're trying to determine whether or not a fetus is a living human being on the basis of his or her eligibility to be covered by an insurance product (and why anyone would regard an insurance company as a legitimate arbiter of this question one way or the other is completely beyond me), then the provision of prenatal care aimed at the unborn child's benefit should be quite relevant. Still, I'll play along on your terms.
First, I would imagine there's vanishingly little demand for such a product (although it does seem to be offered in parts of Asia). The reasons you've given above for why people purchase life insurance policies on their children seem to me, to be perfectly frank, to be concerns only those who have been solicited by an insurance advertisement or salesman would have (and only that subset of these people who are sufficiently naive as to be moved by such concerns). When parents learn they're expecting a child, they begin attending to a number of now very urgent tasks. It's hard for me to imagine that many expectant parents would regard the purchase of a superfluous insurance product as among these urgent tasks, nor will the insurance companies have yet had an opportunity to identify them as expectant parents and to prey upon their fears (though this may be changing with the web browsing data that's being sold to marketers -- we've recently received in the mail some solicitations from Similac and Gerber Life Insurance). Tell us -- how many times in your career did an expectant parent approach you to have a life insurance policy issued on his unborn child?
Second, the risk of miscarriage before twelve weeks -- and particularly before six weeks -- is quite high. There's yet further risk of death at and around the time of delivery. The premiums, then, would necessarily be quite high and would deter many even of those who could be talked into believing they needed such a product in the first place.
Third (and closely related to the above), the fragility of the fetus, especially in the early weeks, introduces tremendous moral hazard into any such policy and, due to the nature of pregnancy, it would in many cases be all but impossible to adjudicate whether a miscarriage were due to natural causes or to some nefarious intervention. There would doubtless be those who would seek to profit from this fact, and an insurance company is not going to make itself vulnerable to such persons.
If an insurance company could make good money from doing so, a parent could purchase a policy on the life of his unborn child (just as a pet owner can purchase a policy on the life of his pet). A reasonable person would not draw from the insurance company's issuance of a policy any conclusion as to when human life begins, nor should he now from the company's refusal to issue such a policy.
As it stands, the same insurance company that won't underwrite a policy at six weeks gestation won't underwrite one a minute before birth either. Are we to conclude from this that the fetus "is not a life" one minute before birth and magically becomes "a life" at the moment of delivery?
What about the fact that Gerber will not underwrite a policy until 14 days after birth? Is the neonate "not a life" until he is two weeks old?
What about those who are not eligible for life insurance due to a pre-existing condition. Are they too "not a life"?
To be perfectly frank, eligibility for life insurance seems to me an utterly stupid criterion by which to answer the question of when human life begins, and you've so far given me no reason to think otherwise.