A babies height and weight determine the percentile of growth. This is how they keep tabs on the child’s health and if there is anything wrong.
They can also determine what your child’s height will be full grown. There is a little play in this but I found it to be very accurate for both of my children’s adult height.
http://pediatrics.about.com/cs/usefultools/l/bl_height_pred.htm
I think my wife wanted to be surprised by the sex , just like the old days. It did not matter to me so I was OK with waiting. I don’t know what is gained by knowing the sex in advance unless you want to make sure you get the right color clothes. We had names picked out for boys and girls and we had 2 boys who are now 13 and 17.
I think it stems back to to a high weight = a healthy baby, but also mixed in with how much the woman had to deliver.
Well, the “god forbid” may have something to do with the difference in reaction here. I mean, it sounds a bit like you’re visualizing this hypothetical parenthood as a kind of impending natural disaster, where any sane person would naturally want to find out as much as they possibly could about the details of the catastrophe before it actually hits them.
Okay fine, but I think many parents-to-be view the situation more along the lines of having a wrapped-up Christmas present sitting under the tree. As long as it’s in good condition, you don’t really need to know all the details about what’s inside yet. And in fact, for many people, not knowing all the details in advance makes it more exciting when you finally get to open it up and find out.
I’ve heard of some parents-to-be asking the doctor to write down the baby’s sex and seal it in an envelope, and then they go out to a fancy dinner or the like and open up the envelope there, to make it a special occasion.