Taking history of smoking in pregnant woman and following its effect on fetus is what ?

Ans. is `b' i.e., Prospective coho o Prospective coho study is one in which the outcome (e.g. disease) has not occurred at the time of investigation begins. o In the given question, the outcome has not occurred at the time of investigation begins. Only history of risk factor exposure (smoking) is taken. Then outcome (effect on fetus) is followed in prospective. o This is classical prospective coho study. Types of coho studies Prospective coho study: Known as 'Current coho study' or 'Concurrent coho study' Outcome has not yet occurred when the study has begun: Only exposure has occurred; we look for development of same disease in both exposed and non-exposed groups Examples :- Framingham hea study, Doll & Hills prospective study on smoking & lung Cancer. Retrospective coho study : Known as 'Historical coho study' or 'Non-concurrent coho study' Combines advantages of both Coho study and Case control study Both exposure as well as outcome have occurred when the study has begun: First we go back in time and take only exposure into consideration (cohos identified from past hospital/ college records), then look for development of same disease in both exposed and non-exposed groups Sample size required is same as that of prospective coho study Usually used in occupational cancer studies Examples :- Effect of fetal monitoring on neonatal death; PVC exposure and angiosarcoma of liver. Combined prospective-retrospective coho study : Known as 'Mixed coho study' Combines designs of both prospective coho study and retrospective coho study Both exposure as well as outcome have occurred when the study has begun: First we go back in time and take only exposure into consideration (cohos identified from past hospital/ college records), then look for development of same disease in both exposed and non-exposed groups; later coho is followed prospectively into future for outcome Examples :- Cou-Brown & Doll Study on effects of radiation therapy.