If you are pregnant or know someone who is, then you may have heard that maternal health and wellbeing is important as your baby grows and develops your womb. Over the last thirty years scientists and medical researchers have come to understand the importance of the in utero environment on the developing baby. Our national dietary guidelines tell us that a healthy diet during pregnancy is important for the baby’s physical development. We are now beginning to see evidence that the maternal diet might also be relevant to the developing brain, and the future mental health of children. Pregnancy is an important period where the main hormonal, immune and brain systems are being developed. During this time, the foundations of life-long physical and mental health are being laid, and adequate nutrition is central to healthy stress and emotion-regulation systems. Diet during pregnancy – and even well before conception – is an important target for promoting both future physical and mental health. What do we know? Animal studies have looked at the relationship between maternal diet and offspring behaviour. Feeding animals a high fat diet during pregnancy disrupts the mood-regulation systems in offspring. Offspring of mothers that ate a high fat diet also are more likely to show anxiety or depression-like behaviours than the offspring of mothers who ate normally. New data from mice show that a high fat diet during pregnancy can result in autism-like behaviours in the offspring. There have been similar findings seen in human studies: a large study of over 20,000 mothers and their children led by Prof Felice Jacka and colleagues that showed that the children of mothers who ate an unhealthier diet during pregnancy had higher levels of behaviours – such as aggression, hyperactivity or conduct problems – that are linked to mental disorders. These findings have been replicated in studies in the UK and Europe. Jacka’s Norwegian study also showed that the children’s diets were important too. Young children who ate a diet low in nutrient-dense foods and/or higher in ‘junk’ foods during the first years of life had higher levels of emotional dysregulation, including anxiety, sadness and worry. It’s also important to understand that obesity during pregnancy in mothers is associated with an increased risk for autism spectrum disorders and neurodevelopmental delay. It’s not just Mums either; Dads who are overweight or obese are also more likely to have children with autism spectrum disorders. A good quality diet during pregnancy is made up of a variety of nutrient rich foods such as fruits, vegetables, and high fibre cereals, fish, good quality meats and vegetable oils such as olive oil. A lower-quality diet consists of more processed foods; sugary snacks, highly processed cereals and processed meats. Importantly, both of these dietary patterns are independently related to the mental health of children, suggesting that while many mothers are careful to eat good quality foods, junk foods consumed on top of a fairly healthy diet may still have a negative impact. Early life nutrition – from pre-conception through childhood – is important in influencing the risk for mental health problems in children as they grow. This is very important to understand if we want to think about preventing mental disorders in the first place. Of course, if you have a mental disorder, it’s important to understand that scientists can’t say for certain whether it was what your parents ate or didn’t eat that caused any problems, because genetics plays a huge role, along with other environmental factors and illnesses. We think diet is important though, and if you are planning a baby, and have control over your diet, then a healthy diet will likely benefit everyone’s health (and you’ve got nothing to lose), that goes for Dads too! What do we need to do now? In Australia, national surveys tell us that only a very small proportion of women meet the dietary recommendations during pregnancy. Given this is such an important period for preventing poor health outcomes in children, it is important that we finds ways to best help women to make good dietary choices during pregnancy. We also need to understand better the impact of parents’ diets on the future health of children. What are we doing In collaboration with the Royal Children’s Hospital, we are running a new study that aims to help pregnant women to improve their diets.