RESUMEN
<p><b>OBJECTIVE</b>To investigate the risk factors for congenital external malformation.</p><p><b>METHODS</b>A 1:2 matched case-control study was conducted with 52 cases of congenital external malformation during perinantal period collected from surveillance in Baoan District of Shenzhen City from January to June in 2000.</p><p><b>RESULTS</b>Simple and multiple conditional logistic regression analysis showed that the major risk factors for congenital external malformations during perinatal period were preterm labor (beta(k) = 1.4171, s(theta, beta(kappa)) = 0.4601, OR = 4.115), adverse mental stimulus (beta(kappa) = 2.1870, s(theta beta(kappa)) = 0.7873, OR = 8.909), taking medicine (beta(k) = 1.9178, s(theta beta(kappa)) = 0.8072, OR = 6.808) and exposure to hazardous chemicals during early pregnancy (beta(k) = 0.9602, s(theta beta(kappa)) = 0.4262, OR = 2.612).</p><p><b>CONCLUSIONS</b>Congenital external malformation during perinatal period was caused by multiple risk factors and results of the study showed that environmental and mental factors were in obvious connection with its occurrence.</p>