Perspective In the abortion debate, Mother Nature knows best Mahmoud F. Fathalla Professor of obstetrics and gynaecology, Assiut University, Egypt The Supreme Court in the USA, in the recent ruling that abortion is not protected by the Constitution, stated that abortion is not deeply rooted in the history and traditions of the country. 1 This may be so, but a reading in the book of Nature shows that abortion is deeply rooted as an evolved and selected female adaptive reproductive strategy which can be traced back over hundreds of millions of years. Mother Nature views reproduction as a costly investment for the female of the species and recognizes that not every embryo is fit for continued investment and that not every time is a good time for reproduction. Reproductive filtering is Nature’s quality control strategy to filter out embryos unfit for continued investment. Reproductive suppression is Nature’s mechanism to terminate reproduction when conditions are not favourable for continuing with the enterprise, and when the female will do better to conserve her energy and time for future reproductive opportunities when a successful outcome is more likely. The earlier the decision to terminate is taken, the less will be the cost of the loss to the mother. In addition, Mother Nature has provided the female with empowering reproductive strategies to decrease the need for abortion. Reproductive filtering