Association between the serum insulin‐like growth factor‐1 concentration in the first trimester of pregnancy and postpartum depression

Aim Patients with major depression present with an increased serum insulin‐like growth factor‐1 (IGF‐1) concentration. However, the longitudinal relationship between serum IGF‐1 levels and depression development remains unclear. This study aimed to investigate the longitudinal association between the serum IGF‐1 concentration in the first trimester of pregnancy and postpartum depression development using data obtained from the Japan Environment and Children's Study (JECS). Methods The JECS included 97 415 pregnant women; among them, 8791 were enrolled in this study. Data regarding depression in the first trimester, postpartum depression development at 1 month after childbirth, and other covariates were collected using a self‐administered questionnaire. Serum IGF‐1 levels were measured in the first trimester of pregnancy. The participants were divided into four groups according to the serum IGF‐1 level. Results In the first trimester, serum IGF‐1 levels were not significantly associated with psychological distress in pregnant women. In the longitudinal analyses, however, postpartum depression development in mothers within the highest quartile for serum IGF‐1 concentration in the first trimester was significantly less common than in those within the lowest quartile (odds ratio 0.48, 95% confidence interval 0.30–0.79). Conclusion Pregnant women with a high serum IGF‐1 concentration in the first trimester were less likely to develop postpartum depression than those with a low concentration. A high serum IGF‐1 concentration during pregnancy may help to protect against postpartum depression development.