Courtesy Prof. AvSundram ji Hyd.

A theory  of numbers in  astrology.

a union (sex act) between a man and woman creates a child.- 5 house.

a man must a capacity to perform--8 house,

he must have a partner--7 house.

he must have a chance to perform--12 house.

he must perform with vitality-- 3 house.

we know that 3,6,10 and 11 are upachaya meaning growth rasis..

now we find  5 house is 3 to 3,

5 house is 6 to 12,

5 house is 10 to 8 and 

5 house is 11 to 7.

hence 5 house is one of the growth rasi of  3,7,8 and 12

it means 3,7,8 and 12 houses have a role to play in getting a child.