Breastfeeding 'can enhance a child's IQ': Longer a mother chooses to feed baby the better their intelligence scores aged seven US researchers found breastfeeding can enhance language skills from three They recommend babies are fed solely on breast milk for first six months The apparent decision by the Duchess of Cambridge to breastfeed has been given a boost by fresh evidence showing it can help raise a baby's IQ. The longer the child is breastfed - ideally exclusively - the higher the intelligence scores are at the age of seven. The study also found breastfeeding can enhance language skills from the age of three. The Duchess of Cambridge's apparent decision to try to breastfeed Prince George has been boosted by evidence showing it can raise a child's IQ The US researchers recommend babies are solely fed on breast milk for the first six months and are given the chance to breastfeed until a year old. However, British experts warned that delaying the introduction of solid foods until six months at the earliest might leave some babies feeling hungry. It emerged yesterday that the Duchess has at least one maternity dress made for breastfeeding and was given encouragement in hospital to help her baby George start on her milk. Earlier research has shown breast milk protects babies against stomach bugs, chest infections, asthma and allergies, and confers health advantages in later life. But only a small number of women in the UK breastfeed their babies for long periods and the number of new mothers starting in 2011 fell slightly to 73.9 per cent. Barely 2 per cent of babies are breastfed exclusively for six months. The latest study included 1,312 mothers and children who had taken part in Project Viva, a long-term investigation of pregnancy and child health in the US. It found seven-year-olds breastfed for the first year of life were likely to score four points more in a test of verbal IQ than bottle-fed children. Verbal intelligence scores at seven increased by 0.35 points for every extra month of breastfeeding. Three-year-olds also benefited, having higher scores in a language-acquisition test the longer they had been breastfed. Exclusive breastfeeding had the greatest effect. The US team of researchers reported the findings in the journal JAMA Pediatrics. The scientists, led by Dr Mandy Belfort, from Boston Children's Hospital, said: "Our results support a causal relationship of breastfeeding in infancy with receptive language at age three and with verbal and non-verbal IQ at school age. These findings support national and international recommendations to promote exclusive breastfeeding through age six months and continuation of breastfeeding through at least age one year. A number of factors that might have influenced the results, including home environment and mothers' IQ, were accounted for by the researchers. Children took part in several tests, including the Peabody Picture Vocabulary Test at age three and the Kaufman Brief Intelligence Test at age seven. Certain nutrients in breast milk may benefit the developing infant brain, it has been suggested. One of these is docosahexaenoic (DHA), which is abundant in fish. Part of the research looked at whether mothers' fish consumption was linked to the benefits of breastfeeding but the results were not statistically significant. Kate has had at least one maternity dress made for breastfeeding, it has emerged It is thought that chemicals naturally present in breast milk can aid brain development, but skin to skin contact and bonding during breastfeeding may also play a part. But Clare Byam Cook, an independent breastfeeding counsellor and former midwife, said: "It's best to keep an open mind about what your baby's individual needs are. Many babies feel hungry if they only get breast milk and most need solids before six months. She said mothers who can breastfeed their babies easily are giving them a great start in life. She said: 'Most women who give up find it too difficult to continue. The Duchess was given encouragement in hospital to help baby George start on her milk 'They are not unaware of the benefits to the baby, they have been brainwashed into thinking if they don't their baby will miss out and it can be a very worrying time. Ms Cook, the author of Top Tips For Breast Feeding and Top Tips For Bottle Feeding, said there was new evidence that breastfeeding exclusively for six months may not be best for baby, putting them at risk of allergies, food aversion and even obesity. Babies can be safely given solid foods at least eight weeks earlier in life than official Department of Health guidelines telling women to breastfeed exclusively for the first six months, according to researchers.