Not once formed. For your statistic to be true, we would have to include fertilized eggs as well, BEFORE implantation.
Out of six children, I only miscarried one BEFORE it was fully formed i.e. at six weeks gestation. None were miscarried after being formed.
St Augustine drew the distinction between formed and unformed fetuses. These days the abortion clinics request that a woman waits until AFTER the fetus is six weeks old before having an abortion so that they can view it on the monitor. There is something very, very wrong with that policy, IMO.
Usually, when an unformed fetus (i.e. an embryo, blastocyst or zygote) is naturally rejected by the woman's body, it is because there is something wrong with it. In other words it is non-viable or severely handicapped. This natural occurrence is very different to people going to the abortion clinic and waiting until after six weeks gestation, when, in actual fact, because it has not been naturally aborted yet, the embryo is, most likely, not severely handicapped.
Also, there are stages of development which should be respected. Once the brain starts being formed (before six weeks gestation), some people believe that the child's soul is present. That should be respected.