Like many molds, fungi, insect larvae and other parasites, it seems that human fetuses can gestate in a variety of places. Apparently the fertilized egg can "fall out" of the fallopian tube and implant anywhere in the mother's abdomen. If it happens to land on a spot which has a particularly rich supply of blood and nutrients, it will grow into an actual baby. Several healthy babies have been born after gestating in the liver [BBC]. One doctor interviewed for the article aptly referred to such a child as a "miracle baby." Surely it is part of God's magnificent plan for all things, that some zygotes develop in the liver, in order that it may be called a miracle when they don't die... It may seem like God is just doing things the hard way, but I speculate that such occasional wierdness is motivated by His desire to see the word "miracle" in print more often.