First, its not predicting the future. The gender of the fetus is already determined.
We chose not to know. I would call it a “hashkafic” reason – I think it is definitely more exciting in general at birth when no one knows.
Our Rav allows preparations before birth if there is a reason to (stroller on sale, make life easier etc), so planning wasn’t an issue.
With our first, I gave birth ten minutes before Shabbos. We were on the phone with our Rav about an hour before Shabbos talking about if its a boy, when would the bris be? If I had given birth 19 minutes after candle lighting, the Bris would have been on sunday. If it were 42.5 minutes after shkiah, it would have been on Shabbos. I thought it was kind of interesting.
We had our shalom zachor in the hospital. According to my Rav, the SZ is where the baby is. So the attendants of the SZ were my husband, my mother, my sister and my frum roomate. Nice and simple with food from Satmar Bikur Cholim.