Inadequate blood flow through the placental intervillous spaces to enable sufficient transmission of nutrients, oxygen, and fetal wastes. It may be caused by diminished maternal cardiac output due to anemia, heart disease, regional anesthesia, or supine hypotension; vasoconstriction due to chronic or pregnancy-related hypertension or uterine overstimulation; vasospasm due to pregnancy-induced hypertension; vascular sclerosis due to maternal diabetes or collagen disease; or intrauterine infection. It increases the risk for intrauterine growth retardation.