Objective To analyze the effects of pre-pregnancy obesity and overweight during pregnancy on the mental health of pregnant women over the perinatal period.Methods We selected 288 pregnant women who underwent perinatal psychological screening tests in our hospital from January 2019 to December 2019 as the subjects, using general information questionnaire, Self-Rating Anxiety Scale (SAS), Self-Rating Depression Scale (SDS) and Symptom Checklist-90 (SCL-90) to investigate the mental health of pregnant women and to analyze the effects of pre-pregnancy obesity and overweight during pregnancy on the mental health of them. Multivariate Logistic regression analysis was performed to explore the factors affecting the mental health of pregnant women.Results A total of 275 valid questionnaires were collected, and the incidences of pre-pregnancy obesity and overweight during pregnancy were 17.82% and 30.18%, respectively. The scores of SAS, SDS and SCL-90 in pregnant women with pre-pregnancy obesity and overweight during pregnancy were significantly higher than those of others (P < 0.05). The incidence of psychological dysregulation in pregnant women was 24%, and the mental health status of pregnant women was not affected by their education level, whether they were primiparous, and the history of abnormal pregnancy or unplanned pregnancy (P > 0.05). However, the metal health status was different among pregnant women with distinct age, pre-pregnancy weight, weigh gain during pregnancy, and household monthly income per person (P < 0.05). The multivariate Logistic regression analysis showed that pre-pregnancy weight [O^R = 2.152 (95% CI: 1.457, 3.178)], weight gain during pregnancy [O^R =9.226 (95% CI: 4.765, 17.864)] and household monthly income per person [O^R = 0.524 (95% CI: 0.299, 0.918)] were the main factors affecting the mental health of pregnant women, among which pre-pregnancy obesity and overweight during pregnancy were risk factors, while the household monthly income per person more than 4,000 yuan was a protective factor (P < 0.05). In addition, the mental health of pregnant women was not affected by the age (P > 0.05).Conclusions Pre-pregnancy obesity and overweight during pregnancy are the main factors contributing to negative emotions of pregnant women. Thus, the weight management should be emphasized in clinical practice to reduce the incidence of negative emotions in pregnant women.