I think baby weight has a lot to do with your pre-pregnancy weight and height.
You can use the below calculator to estimate your babies birth weight. It gives you and average weight plus a weight that falls in the upper and lower percentiles. You just enter your height in CM and pre-pregnancy weight in KG.
It gives the baby weight in Grams, so I've included a link to a converter for those of you like me who need to have pounds and ounces to make any sense of the results
www.metric-conversions.org/weight/grams-to-pounds.htm
It gave me an average weight of 6lb 9oz for my son - He was 6lb 9.5 oz at birth....Having said that my Moms first baby was 6lb 9.5 oz, so perhaps its genetic! (Hubby weighed 6lb 6.5 at birt and I weighed 4lb 7oz).
www.hutchon.net/CESDIcalc.htm
To convert feet and inches to CM use
http://www.onlineconversion.com/length_common.htm