Sometimes, I do receive questions from clients during bazi consults like how many children they can have and whether the first child is a girl or boy. In bazi study, there is a table which you can make reference to to help you determine number of children that one can have. I have uploaded here for you to take a look. This table is plotted in accordance to a poem as follows:
長生四子中旬半，沐浴一雙保吉祥。
冠帶臨官三子位，旺中五子自成行。
衰中二子病中一，死中至老沒兒郎。
除非養取他人子，入墓之時命天亡。
受氣為絕一個子，胎中頭產有姑娘。
養中三子只留一，男女宮中子細詳。
How to use this? For example, if you are a guy and your daymaster is Ding, your male child element is represented by Gui. So, from the table, zoom into Gui and then look for the earthly branches that is residing in your child palace. So, if your child palace is Zi, you will have 3 sons. That will give you the answer.
Nevertheless, personally I feel that this system does not produce consistent result in today’s society. You can try it out though.
In fact, with today’s advanced medical technology and prevalent practice of contraception, it is no longer of relevance to quantify, based on bazi, the number of children one will have, let alone predicting the gender of first baby.
Interestingly, based on my fengshui research and experience, the gender of baby born in the house is also closely related to the layout of the house and the room that one is living in plus the location that the main door is located. It boils down to the concept of yin and yang and the forms of the house. This is also a technique which I help couples who wish to plan for the gender of their next child by telling them when to make love, how to make love, where in the house to make love.