A Tuesday afternoon webinar has bought attention to the under-reported racial disparities in maternal mortality.

Black Mamas Matter: Reproductive Justice and Black Women’s Maternal Health was co-hosted by SisterSong Women of Color Reproductive Justice Collective and the Black Mamas Matter Alliance. The webinar caught Twitter’s attention as #BlackMamasMatter began trending on Tuesday afternoon:

The Centers for Disease Control and Prevention defines a pregnancy-related death as:

“The death of a woman while pregnant or within 1 year of pregnancy termination–regardless of the duration or site of the pregnancy–from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes.”

According to the CDC, Black mothers are three to four times more likely than White moms to die from from complications during pregnancy or childbirth. In 2011, the CDC reported that Black women comprised 42.8 percent of deaths resulting from pregnancy or childbirth whereas White women constituted 12.8 percent of this population. The reports found that geography and workplace environments do have some bearing on these racial gaps.

In March, the Black Mamas Matter Alliance told Univision that systemic racism is clearly at play in these deaths.

“Black women are treated differently because of the color of their skin,” psychologist and researcher Fleda Jackson said in the Fusion documentary The Naked Truth: Death by Delivery which examines maternal mortality rates . “Many don’t know their rights and suffer abuses, and they don’t have insurance. And they also suffer from sexism. They are Black and they are women. There is no rest for them in these circumstances.”

ProPublica reports that the deaths of expectant or new Black moms are more difficult to to track on social media channels. The nonprofit organization also claims that among developed countries, the U.S. has the highest maternal mortality rates.

Organizations like the Healthy Start Organization of the Health Resources and Services Administration work towards reducing maternal mortality.

“Through our Healthy Start program we are also focusing on the neighborhoods that have the highest severe maternal morbidity rates in North and Central Brooklyn,” Assistant Commissioner at the New York City Health Department Dr. Deborah Kaplan told Univision Noticias in March. “We’re also supporting the prenatal care programs that help to reduce preterm births. We must talk about this injustice. We have a great opportunity to make a difference.”