Materials and Methods: This cross-sectional study was conducted on 2040 pregnant women aged 14 to 48 years, in Talegani teaching hospital of Tabriz University of Medical Sciences from January 2017 to December 2019. Three trained midwives collected relevant information from the women on the admission to the labor room and recorded pregnancy outcomes. Chi-square test of independence with post hoc tests and logistic regression analysis were used for data analysis. Odds ratios with a 95% confidence interval and contributing effect sizes were reported. The significance level was set at P ≤ 0.05.

Results: The majority of participants (62.67%) colored their hair in the third trimester. There was no statistically significant association between hair coloring and neonate 1-minute (P = 0.23) and 5-minute Apgar scores (P = 0.99). The logistic regression model did not confirm a rise in overall neonatal complications (NCs) associated with hair coloring at any time during the pregnancy (odds ratio [OR]: 0.027, P<0.001). Higher rates of low birth weight (LBW) were seen among those who dyed their hair in the preconception period and third trimester compared to the woman who colored their hair in the first and second trimesters (P<0.001).

Conclusions: We observed associations between hair coloring and LBW, however there were no increased odds for NC. The evidence for the safety of hair dye during pregnancy is still limited.