but since you have a profit-based model, excluding planned (or unplanned for that matter) pregnancies from coverage is the same problem as excluding pre-existing conditions. insurance companies cherry-pick the risk pool to increase profits - they only want to give insurance to people unlikely to need it.
for private insurance to provide any social value, you need a large risk pool that includes healthy and high-risk patients, and the insurance companies must be required to actually cover people who need medical care.
the healthy can't be allowed to opt out, and the insurance companies can't be allowed to decline coverage to anyone in the group.