Pope Francis made the comments during a Vatican conference on abortion issues. "Every child is a gift," he said.
Pope Francis reiterated Saturday that abortion is unacceptable, saying its use amounted to the hiring of a "paid killer".
"Is it lawful to eliminate a human life to resolve a problem? It is lawful to hire a paid killer to resolve a problem?" Pope Francis asked during a conference at the Vatican on the use of abortion when the unborn child is found to have a serious illness.
"No human being can ever be incompatible with life," he said, adding: "Every child is a gift that changes the history of a family ... and this child needs to be welcomed, loved and cared for."
In cases where the child may not live for very long, medical care is not wasted but by gaining time, allows parents to prepare for the death.
"That child will remain in their lives forever," he said.
Pope Francis used similar "paid killer" remarks in relation to abortion in October 2018, sparking a sharp reaction in medical circles.
His latest comments followed the move on Friday by Pope Francis to appoint women to a key Vatican department for the first time since it was founded more than 50 years ago, a move welcomed by Catholic women's groups as a significant advance.
Three nuns and one lay woman were appointed councillors in the office of synods, which prepares major meetings of world bishops held every few years on a different topic.
Pope Paul VI founded the Synod of Bishops in 1965 as a body to advise popes. A Vatican spokesman said they were the first women members in its history.
Two of the four are Italian - Sister Alessandra Smerilli, an economics professor, and Cecilia Costa, a sociology professor. The others are Sister Maria Luisa Berzosa Gonzalez of Spain and Sister Nathalie Becquart of France.
"It is great news because until now there were no structures for women to have an influence on synods while they are being prepared," said Zuzanna Fliosowska, general manager of Voices of Faith, an international advocacy group that promotes a greater role for women in the Church.
More than half of the world's 1.3 billion Catholics are women and the membership of female religious orders is about three times larger than that of male orders.