The purpose of this study was to examine the risk factors associated with pre-term labor (PTL) (< 37 gestational weeks) and low birth weight (LBW) (< 2500 gm) infants in a healthy Taiwanese population. From December 1998 through June 1999, a total of 633 healthy pregnant women were recruited at three teaching hospitals in Taipei. Using a prospective study design, the pregnancy outcome information was followed up by telephone or from medical records during the first month postpartum. Data were statistically analyzed by multiple logistic regression. The prevalence of premature births was 5.4%, and the prevalence of LBW infants was 5.1%. Pre-term births were significantly associated with high self-reported fatigue scores (OR = 3.45); extreme maternal age (< 20 and >/= 35 years, OR = 2.38); history of abortion (>/= 2, OR = 3.11); maternal height (</= 158 cm, OR = 1.73); low income (OR = 1.88), and multiple pregnancies (OR = 18.78). The risk for low birth weight infants was significantly increased when the woman had an extreme maternal age (OR = 2.65), nulliparity (OR = 1.64); multiple pregnancies (OR = 9.3) and no domestic helper (OR = 1.65). The study provides a reference basis for prenatal care.