Father Frank Pavone, a key proponent of the Roman Catholic Church's pro-life movement, has devoted his life's work to ending abortion, euthanasia, embryonic stem cell research, and other techniques and procedures that he believes threaten human life from conception to death. His contributions to the pro-life movement include founding a new religious order called the Missionaries of the Gospel of Life and participating in high-profile protests and television interviews for the pro-life cause. In doing so, his actions and efforts have helped define the Catholic Church's stance on modern issues regarding embryology and reproductive rights.

Horatio Robinson Storer was a surgeon and anti-abortion activist in the 1800s who worked in the field of women’s reproductive health and led the Physicians’ Crusade Against Abortion in the US. Historians credit Storer as being one of the first physicians to distinguish gynecology, the study of diseases affecting women and their reproductive health, as a separate subject from obstetrics, the study of pregnancy and childbirth. Storer was one of the first physicians to successfully perform a Caesarian section, or the removal of the fetus through a surgical incision, followed by the removal of the woman’s uterus, a procedure which would later be known as Porro’s operation. Storer was also an anti-abortion activist who believed that public attitudes toward abortion were too relaxed and that the laws did not effectively punish what he deemed to be the criminal act of abortion. Historians credit Storer with leading the Physicians’ Crusade Against Abortion, which they consider largely responsible for the increase in laws criminalizing abortion in the late 1800s.

Although the concept of quickening was not developed initially by the Roman Catholic Church, much of their histories are intertwined. Quickening, the point at which a pregnant woman can first feel the movements of the growing embryo or fetus, has long been a pivotal moment in pregnancy. Historically, it has also been a pivotal moment for law and the Church in deciding the criminal and religious sanctions for women who intentionally procured an abortion.

Pope Innocent XI, born Benedetto Odescalchi, made considerable contributions to the Roman Catholic approach to embryology by condemning several propositions on liberal moral theology in 1679, including two related to abortion and ensoulment. His rejection of these principles strengthened the Church's stance against abortion and for the idea of "hominization," meaning the presence of human qualities before birth.

St. Augustine of Hippo, born Aurelius Augustinus to a respectable family in the year 354 CE, is now considered one of the foremost theologians in the history of the Catholic Church. His writings, including his philosophy regarding life in the womb and the moral worth of embryos, influenced many other great thinkers of his time and throughout history.

The "Humanae Vitae," meaning "Of Human Life" and subtitled "On the Regulation of Birth," was an encyclical promulgated in Rome, Italy, on 25 July 1968 by Pope Paul VI. This encyclical defended and reiterated the Roman Catholic Church's stance on family planning and reproductive issues such as abortion, sterilization, and contraception. The document continues to have a controversial reputation today, as its statements regarding birth control strike many Catholics as unreasonable.

The principal work of St. Thomas Aquinas, the Summa Theologica is divided into three parts and is designed to instruct both beginners and experts in all matters of Christian Truth. It discusses topics central to Christian morality, ethics, law, and the life of Christ, providing philosophical and theological solutions to common arguments and questions surrounding the Christian faith. The views presented in this body of writing are currently upheld in large part by the modern doctrines of the Roman Catholic Church. Interesting references to and insights on ensoulment and embryology, as well as other topics discussed in Summa Theologica, indicate a strong Aristotelian and Augustinian influence.