A study to evaluate the relationship between smoking exposures taken during PNC visit and the child bih weight after delivery. This type of study is-
**Core Concept**
The question is testing the understanding of a research study design that evaluates the association between an exposure (smoking during pregnancy) and an outcome (child birth weight). This is a classic example of an observational study.
**Why the Correct Answer is Right**
The study described is an example of a **cohort study**, where a group of pregnant women who smoked during prenatal care (PNC) visits are compared to those who did not smoke, in terms of their child's birth weight. This study design allows researchers to examine the relationship between the exposure (smoking) and the outcome (birth weight) over time. The cohort study is particularly useful for investigating chronic exposures like smoking and their potential effects on long-term outcomes, such as child birth weight.
**Why Each Wrong Option is Incorrect**
**Option A:** A **case-control study** is not the correct answer because it involves comparing individuals with a specific outcome (e.g., low birth weight) to those without the outcome (e.g., normal birth weight), but it does not involve following a cohort over time.
**Option B:** A **cross-sectional study** is not the correct answer because it involves measuring exposure and outcome at a single point in time, without accounting for temporal relationships between the two.
**Option C:** An **experimental study** is not the correct answer because it involves manipulating the exposure (e.g., smoking) to see its effect on the outcome, which is not the case in this observational study.
**Clinical Pearl / High-Yield Fact**
Remember that cohort studies are particularly useful for investigating chronic exposures and their long-term effects on health outcomes. This study design can provide valuable insights into the relationships between risk factors and disease, but it is subject to confounding variables and biases.
**Correct Answer: C. Cohort study.**