Previous studies have found that women who reported their pregnancies were 'unwanted' (rather than 'wanted' or 'mistimed') had children who were approximately 2.4 times as likely to develop schizophrenia by the age of 28 and another study has found that unwanted pregnancy leads to a 1.75 times greater risk of the child developing schizophrenia. Researchers in Sweden looked further into this link by studying 166 people, 91 of whom were deemed to be at normal risk i.e. their mothers had not suffered from psychosis and 75 of whom were deemed to be high-risk i.e. their mothers had suffered from psychosis. Unwanted pregnancy was found to be related to an increase in the risk of schizophrenia but only in the high-risk group where it interacted with the genetic risk for the condition. Unwanted pregnancy was also found to be related to an increased risk of affective (mood) disorders. Other stresses in pregnancy, compiclations in and around birth, birth defects and stresses in early childhood were all examined in the study but could not explain the link between unwanted pregnancy and mental illness.
McNeil, T.F. ... [et al] - Unwanted pregnancy as a risk factor for offspring schizophrenia-spectrum and affective disorders in adulthood: a prospective high-risk study Psychological Medicine June 2009, 39(6), 957-965