I considered not finding out but you need to really think and work out whether you are they type of person who when the baby is born and you find out its not what you wanted, will be so over whelmed that you simply wont care any more.
Or if you will be disappointed when you hear the words "its a boy" straight after birth.
For me as someone with a history of post natal depression and not bonding with my baby (NOT gender related) I worried that I would spend 9 months building myself up to the possibility of a girl, and then when it wasn't a girl at birth I might feel such a disappointment that I didn't bond because I was still adjusting.
I decided that it was better to have that extra time while pregnant to get used to the idea of a 4th boy and get over the disappointment so that when he was born I didn't feel anything but love and happiness that he was finally here.
It was going crazy for those first 16 weeks going back and forth between whether it was a boy or girl, and crying over it and praying.
When I had my scan and found out it was a boy I was fine. I finally knew and could stop torturing myself.
For some people not finding out works because they are so in love with their baby when they are born they don't even think about the gender. For others its better to know and prepare yourself.
I was not enjoying my pregnancy and I felt awful because I wanted to enjoy every moment knowing there was a chance it was my last, and having taken so long to get pregnant in the first place. Once I knew I was having another boy, I saw the excitement on my boys faces, people stopped saying "wonder if its a girl, oh thats a sign of a girl", we named him, started looking at things for him, bought him some clothes. And I am enjoying my pregnancy much more.