No, miscarriage is the term used for a pregnancy that ends on it's own, within the first 20 weeks of gestation. This happens prior to pregnancy, and most are completely unaware that fertilization has occurred.
You think up to 50% of pregnancies end in miscarriage?
pregnancy preg·nan·cy (prěg'nən-sē)
n.
1. The condition of a woman or female mammal from conception until birth; the condition of being pregnant.
2. The period during which a woman or female mammal is pregnant. Also called cyesis.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company
miscarriage mis·car·riage (mĭs'kār'ĭj, mĭs-kār'-)
n.
1. Premature expulsion of a nonviable fetus, especially before the middle of the second trimester of gestation; spontaneous abortion.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Pregnancy is from
conception until birth. Before pregnancy there is no fertilized egg.
And a miscarriage is a miscarriage, even if the person does not know they are pregnant.