This study determined whether maternal bisphenol A (BPA) exposure influences birth outcomes through oxidative stress and estimated the daily intake of BPA through breast milk for infants. One hundred and eighty-six pregnant women without pregnancy complications were enrolled and maternal urine was collected in the third trimester. Postnatal breast milk was collected in the first and third months after delivery. Concentrations of BPA were determined through ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Generalized additive model-penalized regression splines and a multivariable regression model were employed to determine the effects of BPA exposure and oxidative stress levels on birth outcomes. A causal mediation analysis was conducted to clarify the mediation effects of oxidative stress due to maternal BPA exposure on birth outcomes. The daily intake of BPA in breast milk was calculated using probabilistic risk assessment methods. The geometric means (geometric standard deviation) of BPA levels for maternal urine and first- and third-month breast milk were 2.19 (2.88) μg/g creatinine., 1.35 (3.53) ng/g, and 3.17 (2.97) ng/g, respectively. No significant mediation existed among maternal BPA exposure, oxidative stress level, and neonatal head circumference. Three percent of 1-monthold babies and 1% of 3-month-old babies exceeded the BPA tolerable daily intake of 4 μg/kg-bw/day proposed by the European Food Safety Authority. This study revealed the BPA exposure profile for pregnant women and infants in northern Taiwan. The marginally significant correlation between maternal BPA exposure and neonatal head circumference should be considered.