Is there a difference in the average weight of children born to black and non-black mothers?

Does smoking during pregnancy affect a baby's birth weight? Is it sensible to use this model to describe the rate at which a baby puts on weight over a pregnancy? Are there any extremely premature babies (the typical gestational period for humans is 40 weeks) who influence the fit of this model, and should they have this influence?

Are the effects of any variable different for different levels of another variable e.g. does the longer a mother experiences in education have the same relationship with birth weight for black and non-black mothers?

You might like to illustrate some of your findings with tables and/or graphs.