Overstretched health visitors have been forced to care for up to 2,400 families with newborns at a time, 10 times the recommended number, according to the sector’s most senior figure.

Prompting fears that breastfeeding rates will drop to new lows and a generation of babies could face a troubled future, Cheryll Adams, the chief executive of the Institute of Health Visiting, told the Guardian that as sickness and redeployment struck, some health visitors were having to care for thousands of families.

“In the last five years we have seen the number of health visitors cut by 30%, then during the pandemic, as many as 50% of staff were redeployed in some areas,” she said. “That was devastating for families and for health visitors who were put under immense pressure.”

One health visitor told Adams she was at one stage looking after 2,400 families, when 250 is considered to be a “safe” number.

Health visitors look after health and development from birth until the age of five. Last year, there were 6,931 full-time equivalent health visitors in England, a drop of 3,378 since the peak of 10,309 in October 2015, figures from Labour showed.

Adams praised health workers and their trusts for their innovation and determination to care for newborns and their parents, pointing to services moved online, but said she was fearful of the long-term impact of a lack of face-to-face visits.

In a worse-case scenario, infanticide figures could have increased, while more children and babies will have witnessed domestic violence, she said, adding that if mothers felt lonely or isolated they were at “much greater risk” of perinatal mental illness or post-traumatic stress disorder.

“If perinatal mental health problems are not quickly identified it can have serious implications for both mother and baby,” said Adams. “I am fearful, yes, I think we are going to see a group of babies who will have increased needs, including the need for secondary services as they get older.”

The lack of support for new mothers also risks exacerbating a long-term decline in breastfeeding rates in the UK, which are already among the lowest in the world, experts warned.

A recent unpublished survey by the Unicef UK Baby Friendly Initiative found that 40% of UK infant feeding services reported reduced staffing as a result of the Covid-19 pandemic, while 30% reported that parental access to the neonatal unit had been “very restricted”.

Justine Fieth, of the breastfeeding support network La Leche League GB, said that when the pandemic hit, all its 80 groups moved online. “The majority of mothers have not had face-to-face support, checkups haven’t happened, babies haven’t been weighed,” she said.

Fieth said she had heard from mothers who had been sent home two hours after birth or been told to supplement breastfeeding with formula “just in case”. Many new mothers felt incredibly isolated, she said. “I suspect we will see higher levels of postnatal depression as a consequence.”

Francesca Entwistle, policy and advocacy lead at the Unicef UK baby friendly initiative, said there was as yet no evidence of a fall in breastfeeding rates, and there was anecdotal evidence that some mothers had found it easier to breastfeed because of a lack of visitors.

But she added: “If women get face to face ongoing support they are more likely to succeed, if they get off to a good start … there is a better chance of keeping it going.”

Public Health England said current maternity services data showed the number of infants receiving breast milk as their first feed after birth had been relatively stable since April 2019, and remained at around the same level in April and May 2020. But there was no data for how many babies born during the pandemic were still being breastfed at six weeks.

Joeli Brearley, the founder of the campaign group Pregnant then Screwed, said the stripping back of services could have far-reaching consequences. “We are creating a mental health epidemic,” she said. “You can’t imagine how families with newborns born during the pandemic are feeling. The continuing impact on mothers’ mental health, and the health of their babies’, is really scary.”

Mary Renfrew, professor of mother and infant health at the University of Dundee, urged policymakers to recognise that maternity care could not be “put on pause for any reason”. “Taking resources away from maternity care doesn’t make sense because we know that will create long-term harm,” she said.