IntroductionAgricultural pesticide spray periods increase the pesticide exposure potential of children living nearby and growing evidence indicates that they may affect children's health. We examined the association of time following a heightened agricultural production period, the Mother's Day flower harvest (May), with children's blood pressure (BP). MethodsWe included cross-sectional information of 313 children ages 4–9 years in Ecuadorian agricultural communities (the ESPINA study). Examinations occurred during a period of low flower production, but within 63–100 days (mean = 81.5, SD = 10.9) following the Mother's Day harvest. BP was measured twice using a pediatric sphygmomanometer and BP percentiles appropriate for age, gender and height were calculated. ResultsParticipants were 51% male, 1.6% hypertensive and 7.7% had elevated BP. The mean (SD) BP percentiles were: systolic: 51.7 (23.9); diastolic: 33.3 (20.3). There was an inverse relationship between of time after the spray season with percentiles of systolic (difference [β] per 10.9 days after the harvest: −4.3 [95%CI: −6.9, −1.7]) and diastolic BP (β: −7.5 [-9.6, −5.4]) after adjusting for race, heart rate and BMI-for-age z-score. A curvilinear association with diastolic BP was observed. For every 10.9 days that a child was examined sooner after the harvest, the OR of elevated BP/hypertension doubled (OR: 2.0, 95% CI: 1.3, 3.1). Time after the harvest was positively associated with acetylcholinesterase. ConclusionsChildren examined sooner after a heightened pesticide spray period had higher blood pressure and pesticide exposure markers than children examined later. Further studies with multiple exposure-outcome measures across pesticide spray periods are needed.