When Vanessa, a worker with Japan's 'technical intern' programme, told her supervisors she was pregnant, she says they first suggested an abortion and then pressured her to quit.

One woman speaks of seeing others who had just given birth by Caesarean section rushed from the wards to underground passageways to protect them from bombardment.

But no pregnant women had died of Covid-19 this year as of Feb 15.

The CDC carried out a study involving 379 babies aged up to six months, who were hospitalised in 20 pediatric centers from July 2021 to January 2022.

The distressing incident was detailed in a social media post by the woman's niece, which included footage of the woman sitting on a plastic stool outside the hospital surrounded by a pool of blood.

There was no difference in outcomes based on the timing of vaccination, or on which mRNA vaccine was received or how many doses.

Health authorities see pregnant mothers as key to the campaign, saying they have a greater possibility of serious illness and death if infected with Covid-19.

Data shows only 31% of pregnant women have been vaccinated against Covid-19.

Think tanks and policy researchers have identified China's declining birth rate as a major social policy challenges in the coming decades.

More than 40 expectant mothers have died of Covid-19 in four months.

Some 30,000 pregnant women in the state have been partially vaccinated while more than 9,000 have completed their vaccinations.

Covid-19 vaccines are safe throughout pregnancy and provide no increased risk of abnormalities or miscarriage.