The singer Halsey says she has donated $100,000 to Planned Parenthood, the embattled US women's healthcare provider, after taking part in the global Women's March on Saturday.

The 22-year-old told her Twitter followers that every retweet of her message of support for the march, up to a total of 100,000, would mean $1 for Planned Parenthood, which House Republicans have vowed to strip of funding.

The group provides abortion services as well as sexual health care, pregnancy and relationship guidance and cancer screenings.

It comes as President Donald Trump signed an executive order reviving the Mexico City Policy and blocking US funding for abortion services around the world. Aid organisations said it could result in tens of thousands of women dying, with the decline of the services leading to millions of unsafe abortions in developing countries.

Halsey's message of support said: "I marched on Washington in solidarity with the women I love. The cis women. The trans women. the WOC. The single mothers. The LGBT. Women of every religion, class and origin. And the men who support these women."

She praised Planned Parenthood for providing "a clean, caring facility that treated me with compassion" when she suffered a miscarriage and was ill with endometriosis.

The outgoing Obama administration created a rule to stop states from withdrawing federal money from Planned Parenthood and other health clinics that provide abortions that took effect two days before Mr Trump's inauguration.

Under the rule, states are legally required to distribute federal funds for services related to contraception, fertility, pregnancy, sexually transmitted infections and breast and cervical cancer screening — regardless of whether they also perform abortions.

A non-profit organisation, Planned Parenthood partly uses government grants to pay for contraceptives and health checks as well as cancer and STI screenings for low-earners in the US.