Objective   To study the influencing factors of congenital malfo rmation in different population and to provide scientific evidence for the decision making of the practical community intervention measures of the disease.

  Methods   Case control studies were carried out with 374 congenital malfomation cases, 169 from city and 205 from rural area, collected from Shando ng province.Control groups were collected by pair matching method.All of 748 subjects were inter viewed by the same questionnaire and their plasma was tested by the same laboratory technique.Simple and multiple conditional Logistic regres sion models were used for the data analysis.

  Results   Longperiod from pregnancy to be known, fever(> 38)during early pregnancy, taking febricide and anodyne, exposure to hazardous chemicals during pregnancy, paternal exposure to injurants, negative life events during pregnancy were the influencing factors of congenital malformation in the city.And their OR and Population Attr ibutable Risk percent(PAR%)values were 5.490(13.91%), 3.352(12.18%), 3.501(13.98%), 3.147 (8.09%), 4.495(9.49%)and 1.113(2.48%), respectively.Long period from pregnancy to be known, taking medicines during pregnancy, nutrition feeding during early pregnancy, previous cytomeg alovirus infection, grade of eugenic knowledge, negative life events during pregnancy were the influencing factors of congenital malformation in rural area.And their OR and PAR% values were 3.850(13.34%), 3.952(28.82%), 0.220(16.03%), 2.760(16.06%), 0.305(18.08%)and 1.506 (3.56%)respectively.

  Conclusion   The sorts and function intensities of infuencing factors to the disease were different between city and rural areas.The different intervention strategies and measures should be considered among city and rural population.