The word " Nidhi " means " treasure " . The nine months in the womb is the period when the nine treasures.gifted.by the divine through the presence of the planets are given to the child when he is born. This is why.they are called nidhis. This is why the Garbhadaan Sanskaar is one of the important 16 Samskaras in a persons life.These are Represented by Kubera as a Boon From Lord Shiva and Parvathi http://en.wikipedia.org/wiki/Nidhi
