Background: Decades of rodent research have demonstrated that perinatal maternal choline intake is important for offspring cognition throughout the lifespan, most notably attention and spatial cognition. However, few human studies have evaluated the effect of maternal choline supplementation during pregnancy or lactation on child cognition, particularly during school-age. Objective: To assess the effect of maternal choline supplementation during pregnancy or during exclusive breastfeeding on child cognitive functioning at age 7 years. Design: Women in their 27th week of gestation (“pregnancy cohort”) or in the early postpartum period while exclusively breastfeeding (“lactation cohort”) were recruited to take part in controlled choline feeding studies. Within each cohort, women were randomized to consume either 480 mg choline/d (approximately the Adequate In-take [AI] for pregnancy) or 930 mg choline/d for 12 weeks (pregnancy cohort) or 10 weeks (lactation cohort). Ancillary follow-up studies were conducted to assess child attention, memory, and intelligence at age 7 y. Results: In the pregnancy cohort (n=20), children whose mothers consumed 930 mg choline/d during their 3rd trimester exhibited enhanced attentional control, including improved sustained attention, compared to children whose mothers consumed 480 mg choline/d. Furthermore, children whose mothers consumed 930 mg choline/d during their 3rd trimester exhibited enhanced visuospatial short-term memory capacity compared to children whose mothers consumed 480 mg choline/d. In the lactation cohort (n=18), no consistent benefit of maternal choline supplementation was detected. However, a lack of group differences in breastmilk total choline concentrations in those re-recruited likely precluded a strong test of the hypothesized effects of postnatal maternal choline supplementation on child cognition. Conclusions: Maternal consumption of approximately double the choline AI during the 3rd trimester of pregnancy had beneficial effects on child attention and memory at age 7 y compared to approximately the AI. This study provides the first evidence from a randomized controlled trial that prenatal choline supplementation improves cognitive functioning on behavioral tasks. These preliminary, but compelling, data suggest that the choline AI for pregnancy may not be sufficient to promote optimal offspring cognition. Larger clinical trials are needed to confirm and extend findings from this small follow-up study.