One case in which families may consider selective reduction is when a fetus has a congenital birth defect, that is either incompatible with life outside of the womb or would result in very difficult life circumstances for the baby once born. Such diagnoses would be made following prenatal testing, such as amniocentesis. Selective reduction for medical reasons can also take the mother's health into consideration. A pregnancy with multiple fetuses can pose risks for a mother, a risk that increases with the number of babies that are present. Selective reduction for this reason rarely happens with twins, but for triplets and upward, doctors may even strongly recommend the family to think about selective reduction because of the strain such a pregnancy puts a woman's body under.
Likewise, a uterus that is populated by many fetuses is not an environment that leaves much chance for babies to grow. Triplets, quadruplets, and upward are very often born extremely prematurely for this reason. Selective reduction can be a decision made to give the remaining fetus or fetuses a better chance at going to term in the womb, thereby increasing the chance they are born healthily. This procedure is, of course, controversial. It is not a choice anyone in this situation makes lightly, but many families also know before they conceive that they would not be able to have a selective reduction, for ethical or religious reasons. If that is the case for you, and you need IVF to get pregnant, we strongly recommend that you look into single embryo IVF to lessen the chance they you will be pregnant with multiple babies, and the resulting potential medical problems.