Pregnancy

The National Institutes of Health (NIH) launched the IMPROVE initiative in 2019 in response to high rates of pregnancy-related complications and deaths, also called maternal morbidity and mortality, in the United States.

The IMPROVE initiative supports research to reduce preventable causes of maternal deaths and improve health for women before, during, and after pregnancy. It includes a special emphasis on populations that are disproportionately affected.

The illustrations below show how the human placenta develops. The timeline of placental development shows how the placenta changes over the course of pregnancy. A crucial stage of placental development is when blood vessels in the lining of the uterus are remodeled, increasing the supply of blood to the placenta. This process, called spiral artery remodeling, is also illustrated in close-up.