Shortly after the conception, it becomes quite clear that Vivien isn't experiencing a normal pregnancy. The most unsettling moment for the expectant mother is an encounter with an ultrasound technician, who faints when she checks in on the baby. She quits her job and devotes herself to the church. When Vivien seeks her out, she says that there's something evil inside Vivien, and she saw hooves on the ultrasound monitor.
There are other disturbing aspects of the pregnancy as well. The Harmons find out they're expecting twins, but the doctor says one is much stronger, and leaching resources from the other. The babies arrive early — only about six months in. The other baby is stillborn. It may be on the nose, but it's a clear representation of the battle between good and evil. And this time, evil wins.