Smoking has been shown to be a risk factor for LBW newborns with an OR of about $2\mathrm{.}0.$ Suppose that you want to engage in a nested case control study with $450$ cases of mothers with LBW newborns and $500$ controls $($mothers with normal weight infants$).$ Since your study is nested within an ongoing cohort study, you have access to both urine and serum samples from these women.