ObjectiveThe present study explored the relationship between maternal copper and zinc levels and preterm labor.DesignThe design of the present study was a case-control. Two groups were matched in terms of early-pregnancy body mass index (BMI), pregnancy and childbirth rating, education level, income, and employment status. Blood samples were taken from mothers after meeting the inclusion criteria when admitted to the maternity ward to check copper and zinc serum levels. Demographic and midwifery data were also collected using a questionnaire and patient records. The data were analyzed in SPSS26 using independent-samples T-test, chi-square, Fisher exact test, and regression analysis, and thep< 0.05 was considered statistically significant.SettingBohloul Hospital in Gonabad, Iran.ParticipantsThe subjects were 86 pregnant women visiting the hospital in two cases (preterm delivery) and control (term delivery) groups.ResultsThe mean serum level of zinc in the case group (preterm delivery) (44.97 ± 13.06 µg/dl) was significantly lower than the control group (term) (52.63 ± 21.51 µg/dl), and the mean serum level of copper in the case group (149.82 ± 53.13 µg/dl) was significantly lower than the control group (183.97 ± 71.40 µg/dl).ConclusionAs the findings showed, copper and zinc serum levels in mothers with preterm delivery were significantly lower than mothers with term delivery, which shows the biological role of these elements in the pathogenesis of preterm delivery.