I don’t have any knowledge of a specific case where this might have happened, but I can see how a lawyer might have pleaded such a case in a way that a court might recognize it.
The legal rights of a minor are normally invoked through a legal representative, which in most cases is the child’s parent. However, where the child might have a claim for legal damages against a parent (it happens), the court will appoint an independent legal guardian for the child, and the legal guardian may bring suit against the parent on the child’s behalf.
So far, so good. If the mother was partially negligent in causing the crash-- let’s say the other guy ran a red light, but the mother was travelling too fast to slow down-- she will be partially liable to people who are damaged as a result of her negligence. This would include the child. In fact, claims by a child riding in a car that the parent crashes are not unusual-- they happen often because the parent is insured, so the child is realy recovering money from the insurance company, not daddy or mommy.
Ok, here’s the tricky part: the child was unborn at the time of the accident. This is a little thornier, but many american courts have recognized that a fetus does enjoy some protectible legal rights. For example, babies born with birth defects caused by the mother taking Thalidomide during pregnancy were able to sue the makers of the drug for their injuries, even though those injuries occured prior to birth. Some courts have also recognized “wrongful life” lawsuits by children injured in botched abortion attempts, and a variety of other creative causes of action.
Putting it all together, a crafty lawyer might look at a situation where mommy was hit by an uninsured driver, and see that the only deep pocket in the case is mommy’s own insurance company. So the lawyer has an independent guardian appointed for the child, and sues mommy for her own negligence in causing the accident (and, of counse, mommy is happy to admit to that negligence, much ot the chagrin of the insurance company lawyer defending the case). Voila!
(Ok, I skipped over the part about mommy “allowing” her car to be hit, but I’ll chalk that up to sloppy journalism. In any event, I’m sure a crafty lawuer could come up with a legally sound argument that would still justify a lawsuit against the mother.)