The idea that women should 'eat for two' during pregnancy is a common myth, an expert has said. Jacqui Clinton, health campaigns manager at charity Tommy's, claimed that pregnant women should not need extra food until their third trimester. Even then, they should only consume up to 200 extra calories a day, she revealed. 'Also, it's important to remember that not all calories are equal,' Ms Clinton continued. 'Choosing healthy alternatives such as low-fat yoghurt with banana will provide you with essential nutrients such as calcium, which is important for the growth of your baby. 'However, 200 extra calories from crisps will provide you with very few essential nutrients.' Ms Clinton's comments came after a University of Texas study suggested that a poor diet in early pregnancy could harm the foetal brain. The research, which is published in the Proceedings of the National Academy of Sciences, emphasises the importance of 'good maternal health and diet', according to senior author Dr Thomas McDonald.