Zamir: Blood flow to the uterus

Mair ZamirMair Zamir, Professor Emeritus from the Department of Applied Mathematics at Western University studies the way fluids flow. Zamir came to Western in 1970. At the time, engaged in the field of aeronautics — which relates to the flow of air around an aircraft in flight. Almost immediately, with help from some brilliant minds in the Department of Biophysics at the time, he turned his attention to Medicine, specifically to the area of blood flow. Fast forward almost a half century, he is now helping clinicians understand the remarkable system of blood flow from mother to fetus.

We are never more vulnerable and reliant than when we are in our mother’s uterus. Understanding the processes that may cause a deficiency in blood supply to the uterus such as placental insufficiency or preeclampsia is critical to the survival, in many cases, of both mother and baby.

BloodstreamThe normal mechanism for the control of blood supply within the body consists of adjusting the caliber of blood vessels to increase or decrease blood flow to meet temporary demands. This "quick fix" mechanism is not suitable for the changing demands for blood supply to the uterus during the nine months of pregnancy.

Women’s bodies have adapted to this challenge by developing a complex system of spiral arteries that are unique to that part of the female vascular anatomy.

“In all my years working on blood supply to the heart, the brain, and elsewhere within the body, spiral arteries stand out as a unique curiosity.”

Placenta Front CoverThe rate at which blood flows in our arteries depends on the prevailing resistance to that flow. The longer the space through which blood must flow, the more resistance. In a clever yet very simple stunt, Biology chose spiral arteries to be packed tightly in a very small amount of space, thus providing a reserve of high resistance to flow. In the early stages of pregnancy, the reserve of high resistance is intact, thus keeping blood supply low. As pregnancy progresses, the reserve is gradually purged by trophoblast invasion and transformation of the distal portion of the spiral artery into an open funnel, thus providing the required high blood supply.

Disorders such as preeclampsia, where the spiral arteries stay wound until too late in the pregnancy, leave the baby with not enough blood supply to survive. Zamir’s work, in collaboration with his clinical colleagues, aims to unlock solutions to increase the delivery of healthy babies and the survival of their mothers. The analysis supporting their findings appear in the current issue of the journal Placenta.