Association between age at first birth and depression: National Health and Nutrition Examination Survey (NHANES) 2005-2018

Abstract Background: Over 5% of the world's population suffers from depression, and women are nearly twice as likely to experience it as men. However, the relationship between depressed symptoms and age at first birth (AFB) in women hasn't been thoroughly investigated. This study aimed to evaluate the relationship between AFB and depression in US women. Methods: We used data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES). A total of 9,515 women aged ≥ 20 who have completed Patient Health Questionnaire-9 (PHQ-9) and Reproductive Questionnaire data were selected for the study. PHQ-9 was used to assess depressive symptoms, and total scores ≥ 10 were identified as having depression. Multivariate regression models were performed to estimate the odds ratios (ORs) and 95% confidence intervals (CI), controlling for reproductive factors and other covariates, to analyze the association between age at first birth and the risk of depression in women. Results:In the weighted sample, the prevalence of depressive symptoms was 11.5% among women. Compared to participants with AFB of 27-29 years old (reference group), fully adjusted models showed that the ORs and 95% CI for women with AFB 29 years compared to the reference group. Conclusion:Women with younger AFB are at higher risk for depression. Further research is needed to determine causal relationships and mechanisms between AFB and increased risk of depression.