Etiology of Cleft Lip and/or Cleft Palate in Southeastern Poland Based on Current Observational Study

<b>Background/Objectives:</b> There is a need to search for risk factors of CL/P, which is the most common facial congenital deformity due to its multifactorial etiology. This study aimed to assess the possible external factors influencing the occurrence of non-syndromic CL/P. <b>Methods:</b> Retrospective-prospective case record analysis was performed with a sample of 224 consecutively treated patients. The data were obtained from medical records and questionnaires completed by children's parents. <b>Results:</b> Factors that may have potentially increased the risk of CL/P were as follows: advanced paternal age (<i>p</i> = 0.014), mother experiencing an infection in the first trimester of pregnancy (<i>p</i> < 0.001), maternal passive smoking (<i>p</i> = 0.001) and stress during the first trimester of pregnancy (<i>p</i> = 0.003). Where mothers were treated with folic acid in the first trimester of pregnancy, in the whole sample the risk of a CL/P in newborns was reduced (<i>p</i> = 0.007). Advanced paternal age was unrelated to the occurrence of isolated CL, and stress did not increase the risk of isolated CP etiology. Maternal folic acid intake in the first trimester of pregnancy did not influence CLP occurrence. <b>Conclusions:</b> In a group of children from Southeastern Poland, the occurrence of CL/P was related to advanced maternal age and maternal external risk factors, such as infections, passive tobacco smoking and severe stress during the first trimester of pregnancy. Maternal folic acid intake during the first trimester reduced the risk of CL and CP. Due to the observational nature of the study, the above conclusions should be interpreted as a potential effect.