Pregnancy is a physiologically stressful condition, placing high demands on the mother’s blood volume and metabolism, thus predisposing her to nutrient deficiencies, inflammation, and oxidative stress. The etiology of NDDs is multifactorial, involving genetic predisposition as well as environmental influences. One important factor to consider is the intrauterine milieu in which early fetal development takes place, as several studies show that any disturbances or environmental insults during critical antenatal periods can significantly alter fetal neurodevelopment. This chapter covers some of these environmental insults, as well as pregnancy-related illnesses in mothers that have been linked to altered fetal neurodevelopment. Potential underlying mechanisms for these associations are elaborated, based on available research data from animal as well as human studies. Although the current data does not establish causality, there is enough evidence to warrant more extensive research in the future.