Mental health in the United Kingdom
Agnes Hann of the National Childbirth Trust said, "These findings are shocking, and mean that thousands of women experiencing potentially serious perinatal mental health problems are not getting the support they need. Perinatal mental illness can have a severe and long-term impact on mothers, babies and families. In extreme circumstances, it can result in tragedy – suicide is a leading cause of maternal death." From roughly 10% to 20% of women giving birth experience some type of mental illness such as anxiety and depression or more complex problems like PTSD and psychosis. With about 665,000 births a year in England 66,500–133,000 women a year develop illnesses. In 2016, 13,000 women were treated by perinatal teams while 800 became inpatients. This means the majority were untreated.
Psychological stress and sleep
Chronic maternal stress in pregnancy exposes the foetus to increased levels of glucocorticoid and inflammatory markers which in turn negatively effects the H-P-A axis and disrupts sleep regulation of the foetus. Up until the age of 2 years, children who have been exposed to pre-natal stress have shortened and disorganized sleeping patterns. During early childhood development the child's brain is particularity sensitive to adverse events such as family conflict, maternal post-natal depression or abuse. It is thought that it is via sensitization of the H-P-A axis that an abnormal stress response is developed in response to these events/ stressors which in turn causes emotional disorders and later life sleeping disorders. 
Observations have been made that there is an association between stress, sleep and Interleukin-6 proposing a possible mechanism for sleep changes.