Millions of women worldwide are facing shortages of sanitary products, price hikes, and worsened stigma while managing periods during the coronavirus pandemic, a charity warned on Thursday.

About three-quarters of health professionals in 30 countries surveyed by Plan International, from Kenya to Australia, reported supply shortages, while 58% complained of rising and prohibitive prices of sanitary products.

Around half the respondents cited reduced access to clean water to help manage periods, and a quarter worried about greater stigma or discriminative cultural practices linked to menstruation for women who were trapped at home by lockdowns.

"Periods don't stop during a pandemic, but managing them safely and with dignity has become a whole lot harder," Susanne Legena, chief executive officer of Plan International Australia, said in a statement to mark Menstrual Hygiene Day.

"In many countries, period products have become scarce and vulnerable girls and young women, in particular, are going without," she said, urging governments to include menstrual hygiene in virus response plans and invest in water and sanitation services.

The research follows a study published last week by the Menstrual Health Alliance of India that found nearly a quarter of women there and in parts of Africa had no access to any sanitary products during the pandemic. More women in poorer countries including Bangladesh and Zimbabwe are resorting to using cloth napkins, raising the risk of bacterial infection, health workers told Plan International.

Many girls in rural Zimbabwe were dependent on schools for a supply of pads and a place to dispose of them, said Rachael Goba, a worker with the charity in Zimbabwe.

"They are going to use alternative, unsafe methods such as the cloth and some will even use cow dung. That's how bad the situation is," she told Reuters by phone, adding that water scarcity meant women in lockdown were washing in unclean sources.

"It has reversed all the gains we have made with regards to menstrual hygiene," said Goba.

Others said lockdowns meant garbage collectors had not been coming regularly, leading to pile-ups of waste, and higher prices mean families have sacrificed buying sanitary pads for girls and women.

"I have no income and I have to wonder where I will get $5 for a pad," one girl from Fiji told the researchers.

Even in wealthier countries like Australia and Ireland where stigma and water supply are less of an issue, women reported price rises and shortages.