RESUMEN
<p><b>OBJECTIVE</b>To investigate the effect of night work near the day of ovulation on outcome of pregnancy.</p><p><b>METHODS</b>Daily early morning urine samples were collected from eligible shift women workers, and human chorionic gonadotropin(hCG), follicle-stimulating hormone(FSH), the urinary steroid metabolites of estrogen and progesterone(PDG, E1C) were measured to confirm the day of ovulation and early fetal loss(EFL). Questionnaires were used to know workshift, other occupation exposures, and related information.</p><p><b>RESULTS</b>12 clinical spontaneous abortion(SAB), 18(EFL) and 44 clinical living birth were analyzed in relation to SAB, EFL and night shift near the day of ovulation by using single factor and multi-factor logistic regression. The result showed that night shift on the day of ovulation and the day before or after ovulation was related with SAB both in single- and muti-factorial analysis(single factor: OR = 2.48, 95% CI 1.10-5.60; multi-factor; OR = 3.90, 95% CI 1.28-11.90).</p><p><b>CONCLUSION</b>Night shift near the day of ovulation may be related to SAB.</p>