This is the first study on the HI of phthalates in pregnant Chinese women. 16.3% and 1.9% of women had HITDI (median 0.358) and HIRfD (0.187) >1, respectively. Cumulative phthalate exposure was associated with risks to birth outcomes. The HI of phthalate co-exposure was sex-specifically related to birth outcomes. BMI and gestational age at collection affected the outcomes.