BBC News
By Smitha Mundasad
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England's chief midwife has stepped up her call for pregnant women to get the Covid jab as soon as possible.
Estimates based on GP records and Public Health England data suggest hundreds of thousands have not had the jab, as the number of mums-to-be in hospital with the virus rises.
Other data suggests the Delta variant increases the chance of severe disease.
In the last three months, 171 pregnant women with Covid needed hospital care - but none had had both jabs.
In a letter to midwives, obstetricians and GP practices, chief midwife for England Jacqueline Dunkley-Bent says all healthcare professionals have "a responsibility to proactively encourage pregnant women" to get vaccinated.