The number of women in England still breastfeeding six to eight weeks after the birth of a child has declined, according to Public Health England (PHE).

Just over four in 10 mothers (42.7%) breastfeed their babies when they are six weeks old, according to 2017-18 data. The rate was 43.1% in 2015-16 and 43.8% for 2014-15.

However, the figures reveal stark disparities in breastfeeding rates in different regions – eight in 10 babies were being breastfed in Tower Hamlets in east London, compared with fewer than one in five (18.9%) in Knowsley, Merseyside.

The World Health Organization (WHO) recommends mothers should exclusively breastfeed babies for the first six months until the children start eating solids, then supplementary breastfeeding is encouraged up to two years or beyond.

The findings suggest policies to encourage breastfeeding and persistent messaging from the NHS Start4Life campaign, the WHO, midwives and other medical practitioners are not having the desired effect.

According to Start4Life, the benefits of breastfeeding include protection from infections, and nutritional balance, while breastfed babies have a lower chance of sudden infant death syndrome, childhood leukaemia and allergies, and are less likely to develop diabetes or become overweight when they are older. It says mothers benefit by bonding with their child and burning off more calories, and breastfeeding lowers the risk of developing breast and ovarian cancer, osteoporosis, diabetes and cardiovascular disease.

Prof Viv Bennett, the chief nurse at Public Health England, said breastfeeding was not always easy but was something mothers and babies learned together. “We know some mothers may need support and encouragement to help them start and continue with breastfeeding,” she said. “That’s why we offer trusted advice to parents through our Start4Life campaign resources and to midwives and health visitors through professional guidance.”

The Royal College of Midwives updated its advice in June to tell midwives that women who decide not to breastfeed must be respected for their choice.

Carmel Lloyd, the head of education at the RCM, said typically 80% of women started breastfeeding, but many stopped soon after.

“Low breastfeeding rates in parts of the UK unfortunately indicate a much bigger social and cultural problem that needs to be tackled,” she said. “There are some areas where many generations of women haven’t been given the example of breastfeeding or offered the right support to enable them to initiate and sustain breastfeeding if they chose to breastfeed.

“For women who choose to breastfeed it is so important that they feel supported not only by midwives, but by their family, friends and wider society too, particularly when it comes to breastfeeding in public.”

She called for more investment in specialist midwives and high-quality postnatal support to help women start and keep breastfeeding.