Yes, the Yong Shen is the Child or Offspring line. The Ji Shen (Annoying God) is Parent line, because Parent line can overcome the Child line. For example, if we have a weak Child line that changes to a Parent line then there is difficulty in having a child.
If already pregnant: Child line that changes to Siblings line indicates that the fetus is healthy. Because Siblings line produces Child line. However, the possible downside is that the baby may grow a bit too heavy for the mother. In that case, we immediately cross check with the state of the Self line, because the Self line is very often the conceiving mother. If the Self line is doing well, then it's not likely to be a problem for the mother; otherwise a surgery may be needed, especially if White Tiger comes with the Self line.
This is just to give you some idea on what to analyze in a divination for pregnancy.