Pregnancy and breastfeeding

Researchers have used Child of the New Century (CNC) to learn how circumstances in the very first stages of our lives can influence our health and development.

Drinking in pregnancy

In the age 3 survey of CNC, you completed activities to show which words you understood and spoke, and which colours, letters, numbers, shapes and objects you were familiar with. Your parents were also asked about different aspects of your behaviour, such as how well you got on with other children and how active you were.

Researchers have found that children whose mothers drank heavily while they were pregnant were more likely to have behaviour problems at age 3 than those whose mothers didn’t drink or drank lightly. On average they also did less well in the different activities, although lots of other factors are also important too.

Smoking in pregnancy

Several studies based on CNC have looked at how smoking during pregnancy relates to children’s development. One group of researchers found that babies with mothers who smoked at any point while they were pregnant weighed on average 146 grams less when they were born (around the weight of a smartphone) than babies with mums who did not smoke.  Overall, the more cigarettes a mother smoked a day, the less her baby weighed at birth.

Babies with mothers whose partners smoked around them while they were pregnant also weighed on average 36 grams less (about the weight of a chocolate bar) than those with mothers who were not exposed to smoke.

Another research study has suggested that children are more likely to have behaviour problems at age 3 if their mothers smoke while they are pregnant.

Breastfeeding and child health

An influential study found that babies who were breastfed in the first months of their lives were less likely to go to hospital for diarrhoea or respiratory problems, such as infections and pneumonia.  The researchers estimated that half of hospital stays for diarrhoea, and a quarter of stays for respiratory problems, could be prevented every month if all babies in the UK were fed entirely on breast milk for at least six months.

Breastfeeding and child development

Between ages 3 and 7 you took part in a range of activities to show which words you knew and the patterns you could identify in shapes and images. Studies have found that children who were breastfed tended to do better in these exercises and to have less behaviour problems.

Research has also suggested that there is a relationship between breastfeeding and young children’s ability to coordinate the movements of their arms and legs and to reach milestones such as standing up for the first time and taking their first steps. However, it is important to remember that there are many other factors that affect children’s development too.



Light drinking in pregnancy, a risk for behavioural problems and cognitive deficits at 3 years of age? (2009) by Yvonne Kelly, Amanda Sacker, Ron Gray, John Kelly, Dieter Wolke and Maria Quigley

Light drinking during pregnancy: still no increased risk for socioemotional difficulties or cognitive deficits at 5 years of age? (2010) by Yvonne Kelly, Amanda Sacker, Ron Gray, John Kelly, Dieter Wolke, Jenny Head and Maria Quigley

Light drinking versus abstinence in pregnancy – behavioural and cognitive outcomes in 7-year-old children: a longitudinal cohort study (2013) by Yvonne Kelly, Maria Iacovou, Maria Quigley, Ron Gray, Dieter Wolke, John Kelly and Amanda Sacker

Prevalence of maternal smoking and environmental tobacco smoke exposure during pregnancy and impact on birth weight: retrospective study using Millennium Cohort (2007) by Corinne Ward, Sarah Lewis and Tim Coleman

Breastfeeding and Hospitalization for Diarrheal and Respiratory Infection in the United Kingdom Millennium Cohort Study (2007) by Yvonne Kelly, Yvonne Kelly and Amanda Sacker

Breastfeeding is Associated with Improved Child Cognitive Development: A Population-Based Cohort Study (2012) by Maria Quigley, Christine Hockley, Claire Carson, Yvonne Kelly, Mary Renfrew and Amanda Sacker

Breastfeeding and child cognitive outcomes: evidence from a hospital-based breastfeeding support policy (2012) by Emilia Del Bono and Birgitta Rabe

Breast feeding and child behaviour in the Millennium Cohort Study (2011) by Katriina Heikkila, Amanda Sacker, Yvonne Kelly, Mary Renfrew and Maria Quigley

Breastfeeding and developmental delay: Findings from the Millennium Cohort Study (2006) by Amanda Sacker, Maria Quigley and Yvonne Kelly