Write a report giving a critical appraisal of the case control study by Shaw et al., on "Risks of orofacial clefts in children born to women using multivitamins containing folic acid periconceptionally. The Lancet 1995; 345: 393-396” -- 2

In your report pay attention to the following. 1. Describe the design features that identify this as a case control study and discuss why the authors chose this study design rather than a cohort study. 2. Evaluate the crude (unadjusted) association between “any maternal vitamin use in the period from one month before to three months after conception” and being a “case” of orofacial cleft vs control. Justify your choice of effect measure, interpret the meaning of the result in words as well as numbers and discuss the strengths and limitations of this particular summary analysis. 3. Discuss the impact of the main features of the study design including the selection of cases and controls; whether incident or prevalent cases were used; assessment of exposure; methods used to control for confounding; separation of cases into several sub-groups. 4. Interpret the results of this paper and say whether, based on the evidence from this study alone, you believe that maternal use of multivitamins that contain folic acid decreases the risk of having a child with an orofacial cleft. Justify your interpretation.