The babies were having fun in Olivia's womb. She was only four months into the pregnancy, so the fetal movements weren't strong. Olivia could only vaguely feel them, unlike in the later stages of pregnancy when they would become more pronounced.
Olivia touched her stomach gently, and the babies settled down. Recently, the babies had been very docile. Olivia had terrible morning sickness in the earlier stages of the pregnancy, but at the moment, she felt fine.
It was probably because her babie