Serena Williams has helped donate 4.25 million face masks to schools.

The 38-year-old tennis star - who has two-year-old daughter Olympia with husband Alexis Ohanian - is doing her bit to make sure there are enough face coverings for children in the US to help stop the spread of Covid-19 before schools return later this year by joining forces with the Masks For Kids program.

Serena admitted she is ''grateful'' to be able to help out and educate schools about the resource.

She wrote on Instagram: ''Getting back to school this fall means having #masksforkids to wear.

''I'm teaming up with @bellacanvas, the National School Board Association and @scholasticinc to donate 4.25 million masks to underserved schools and provide educational materials about masks to 54 million students and all 115,00 schools in the United States.

''Through the #MasksForKids program, schools can access affordable masks and educational materials, quickly. In addition to donating 4.25 million masks, another mask will be donated for each one purchased by the schools. I'm grateful to be able to help educate our schools about this resource, and to be given the opportunity to serve so many students. (sic)''

Meanwhile, Serena recently opened up about her battle with migraines and revealed they have gotten worse due to the stress of the coronavirus pandemic.

The sports star has been suffering with pain almost every day.

She explained: ''It's all incredibly stressful. I was dealing with a lot of stress and unknown factors and things that I wasn't used to, and so I think that was contributing to my migraine attacks and making them more frequent.''

To help ease her pain, Serena's doctor prescribed Ubrelvy - which is a drug designed to pain and symptoms during a migraine attack - and the star found it worked so well that she's now signed on as a spokeswoman for the product.