P-557 Objective: Evaluate if exist association between Glyphosate when is applied by aerial spray for the illicit crops eradication (cocaine and poppy) and Time to Pregnancy (TTP) among fertile women (in months). Methods: An ecological study of first pregnancies was undertaken in 3000 Colombian fertile women from five regions with different use of Glyphosate. Women were interviewed regarding potential reproductive, lifestyle and work history predictors of time-to-pregnancy (TTP), measured in months. Fecundability odds ratios (fOR) were estimated using a discrete time analogue of Cox's proportional hazard model. Results: Distribution of pregnancies in relation with months in different regions offers great differences. In the final multivariate model the main predictor is the region adjusted by irregular relationship with partner, maternal age at first pregnancy and, marginally, coffee consumption and self-perception of water pollution. Boyacá a region with traditional crops and recently, illicit crops without spraying (Manual eradication) had the minimal risk and was the reference. Regions: Sierra Nevada (control area, organic agriculture), Putumayo (illicit crops and intensive spray program) and Valle del Cauca, had the higher risk, with the highest risk for Valle del Cauca (fOR 0.15, 95% CI, 0.12, 0.18) a sugar cane region with use of Glyphosate and others chemicals for more than 30 years. Conclusion: The reduced fecundability in some regions doesn't seem to be in direct relation with the use of Glyphosate. The observed ecological differences remain unexplained and may be caused by varying exposures to environmental factors, history of contraceptives programs in the region or psychological distress. Future studies examining these causes are needed. Key Words: Fecundability, TTP, environmental exposure, Glyphosate, caffeine, Herbicides.