Human pregnancy begins whenever a sperm unites with an egg inside the fallopian tube. The newly-minted embryo must then travel along the fallopian tube during the next few days before finally implanting into the wall of the mother’s uterus.

In rare instances, the embryo will fail to reach the uterus, and will instead implant in the fallopian tube along the way, which is a very narrow tube not designed to support a pregnancy. Such “tubal pregnancies” are highly risky, because the wall of the tube can stretch only a limited amount before it will rupture from the increasing pressure of the growing fetus, possibly resulting in the death of both mother and child.

Whenever an embryo implants in the wrong place, whether in the fallopian tube or in another place like the abdomen, such a pregnancy is called “ectopic” (meaning “out of place”). Ninety-seven percent of all ectopic pregnancies occur within the fallopian tube. Ectopic pregnancy is one of the leading causes of maternal sickness and death in the United States, and presents a formidable challenge to the physician who is trying to help both mother and child.

Of the three commonly performed procedures for addressing ectopic pregnancies, two raise significant moral concerns while the third is morally acceptable.

The first procedure involves a drug called methotrexate, which targets the most rapidly growing cells of the embryo, especially the placenta-like cells which attach the early embryo to the wall of the tube. Some have suggested that methotrexate might preferentially target these placenta-like cells, distinct from the rest of the embryo, so that it could be seen as “indirectly” ending the life of the embryo. Others, however, have noted that these placenta-like cells are in fact a part of the embryo itself (being produced by the embryo, not by the mother), so that the use of methotrexate actually targets a vital organ of the embryo, resulting in his or her death. A significant number of Catholic moralists hold that the use of methotrexate is not morally permissible, because it constitutes a direct attack on the growing child in the tube, and involves a form of direct abortion.

Another morally problematic technique involves cutting along the length of the fallopian tube where the child is embedded and “scooping out” the living body of the child, who dies shortly thereafter. The tube can then be sutured back up. This approach, like the use of methotrexate, leaves the fallopian tube largely intact for possible future pregnancies, but also raises obvious moral objections because it likewise directly causes the death of the child.

Interestingly, both procedures are normally presented to patients exclusive of any moral considerations. They are framed strictly as the means to assure the least damage possible to the mother’s reproductive system. Many doctors will admit, however, that these techniques usually leave the fallopian tube scarred, increasing the chances of yet another tubal pregnancy by setting up the conditions for the occurrence to happen again.