Objectives <p>The role of partner substance use as a risk factor for prenatal substance use remains understudied. This study aimed to investigate the association between self-reported partner history of problematic substance use and pregnant persons use of alcohol, cannabis, e-cigarettes, and tobacco during early pregnancy.</p> Methods <p>A total of 82,180 pregnant individuals screened for substance use in Kaiser Permanente Northern California at their first prenatal visit (approximately 8–10 weeks gestation) during 2021–2022 were included. Partner substance use and prenatal substance use were determined via a self-administered questionnaire. Cannabis use was additionally determined by urine toxicology. Adjusted odds ratios (aOR) were calculated using binomial and multinomial logistic regression.</p> Results <p>Among 82,180 pregnant people, 1,010 (1.2%) reported having a partner with history of problematic substance use. Partner history of problematic substance use was associated with higher adjusted odds of any prenatal substance use (aOR = 1.80; 95%CI:1.56–2.08) and prenatal alcohol (aOR = 1.58; 95%CI:1.33–1.87), cannabis (aOR = 1.89; 95%CI:1.57–2.27), e-cigarette (aOR = 3.38; 95%CI:2.43–4.58), and tobacco use (aOR = 3.66; 95%CI:2.63–4.96). Additionally, frequency analyses showed that a partner history of problematic substance use was associated with higher odds of weekly or daily and monthly or less substance use compared to no use.</p> Conclusions <p>Self-reported partner history of problematic substance use was associated with increased odds of prenatal use of alcohol, cannabis, e-cigarettes, and tobacco during early pregnancy. Findings suggest that individuals with a partner with problematic substance use may benefit from targeted prevention prior to pregnancy to reduce substance use during pregnancy.</p>