Hydrops fetalis (fetal hydrops) is a serious condition in which fluid builds up in the tissues of a fetus. This fluid can cause swelling around the heart or lungs, in the belly, or under the skin.

Hydrops fetalis can develop for a variety of reasons, such as from severe anemia, Rh disease, infections, and chromosomal problems.

Even with treatment, fetal hydrops can cause the death of the fetus.