Although current trends indicate that the rate of cigarette smoking tends to be low among women in the Western Pacific Region (<10%), recent epidemiologic data from South Asia (India, Bangladesh) and Southeast Asia (Cambodia, Vietnam, Indonesia, Malaysia) identify that a large proportion of women of reproductive age and older chew tobacco—often as part of a betel quid mixture that includes other potentially harmful ingredients (eg, areca nut). Our findings from currently pregnant women identified during a nationwide survey of adult tobacco use in Cambodia indicate that 13.0% (95% confidence interval [CI] = 8% to 17%) were current users of smoked or smokeless (in the form of a betel quid) tobacco. Most pregnant women who used tobacco indicated that their habit was either initiated (29.1%; 95% CI = 16.3-46.3) or increased (33.7%; 95% CI = 18.3-53.5) during pregnancy. Pregnancy-related symptoms such as morning sickness were reported as the reason for more than half (54.9%; 95% CI = 34.8-73.4) of the currently pregnant users to have started a tobacco habit during their lifetime. Among those pregnant women who did not use tobacco, we found strong associations (odds ratios from 2 to 14) with beliefs about the harmful effects of tobacco on adult health, faith-based beliefs in addictive substances, and beliefs that influential members of the community, health professionals, and children should not use tobacco. Our findings indicate that tobacco cessation and prevention programs in Cambodia should specifically target pregnant and reproductive-age women.