Pregnant women are at a higher risk of caries compared to nonpregnant women, and higher parity is a risk factor for untreated caries and tooth loss. However, it is unknown whether the timing of birth is associated with dental caries experience over time. This study is a cross-sectional study using the National Health and Nutrition Examination Survey (NHANES), 2011-2018. The study population included nonpregnant women 20 years of age or older, who had available data on the oral health examination and age at first birth (AFB). Dental caries experience was defined as the DMFT score (sum of the number of decayed, missing due to caries, and filled permanent teeth). The associations between AFB and DMFT scores were assessed using Poisson regression to compute incidence rate ratios (IRRs) and the associated 95% confidence intervals (CIs). This study included 6,553 women (mean age 53.4 years, SD 15.7). The mean DMFT index score was 13.1 ± 7.4, with younger AFB groups generally having higher mean scores. After adjusting for sociodemographic variables, time since last dental visit, and reproductive health factors, women with an AFB of <18 years (IRR, 1.10; 95% CI, 1.01-1.21) or 18-20 years (IRR, 1.11; 95% CI, 1.01-1.21) had significantly higher DMFT index scores compared to those with an AFB of 30-32 years. This study suggests that younger maternal AFB may be associated with greater dental caries experience. More rigorous studies are necessary to determine how to improve oral health outcomes during pregnancy and postpartum.