Stressful pregnancies linked to behavioural problems in children
Findings from a number of studies suggest that there is an association between mothers who had stressful pregnancies and behavioural problems in their children. In the first study conducted in a developing country, PAUL G. RAMCHANDANI, LINDA RICHTER, SHANE NORRIS AND ALAN STEIN set out to examine whether maternal prenatal stress is associated with an increased risk of subsequent child behavioural problems in a developing country.
The study aimed to explore associations between stressors (i.e. situations that are experienced as a perceived
threat to one's well-being and survival) experienced by pregnant women in their third trimester and the effect it had on child behavioural and emotional development. It also investigated whether particular types of stressors in the period before birth were more predictive of later child problems.
Background to the study
The 953 participants were from Birth to Twenty, a study conducted in Soweto since 1990 and designed to map the physical and psychosocial development of a group of urban children. The vast majority were from socio-economically disadvantaged families.
Those women who were exposed to higher levels of maternal prenatal stress were associated with more than a doubling of the odds of behavioural problems in their children.
The participating mothers were pregnant and delivered their babies during an extremely volatile time in South Africa's history, both politically and socially, as the country made the transition from apartheid to an inclusive democratic system.
The children in the study have become known as Mandela's Children, as they were born in the seven-week period after the release from prison of Nelson Mandela. The participants were thus exposed to significant environmental changes, including high levels of political violence.
The study used data from assessments completed during the third trimester of pregnancy and then at six months, two years, and four years after birth.
Behavioural problems at four years
The authors found that children whose mothers had high stress levels while they were pregnant did not have an increased risk of behavioural problems at age two years, but they did at age four.
Exposure to increased levels of stressors could increase levels of stress-responsive hormones within the mother, exposing the foetus to these and resulting in increased latent risk for psychopathology
Although the study cautions against extending these findings to the whole population (population-attributable risk, or PAR), it gives an indication of the potential importance of prenatal stress for children's development.
The researchers grouped stressful events into four groups to investigate whether specific types of stressors were associated with child behavioural outcomes. The four groups were marital stress (partner violence or relationship breakdown); family stress (fight with family, family member with a drug problem, family member with disability); economic stress (in serious debt, too little money, have to support family in financial need); and societal stress and violence (in danger of being killed or witness to a violent crime).
Those women who were exposed to higher levels of maternal prenatal stress were associated with more than a doubling of the odds of behavioural problems in their children. This is despite controlling for socio-economic status, other prenatal toxic influences, and postnatal depression.
A second key finding was that of the many stressors to which mothers were exposed, those involving families or partners appeared to be the most predictive of later child problems. Estimates from studies in developed countries suggest that up to 10-15% of the PAR for behavioural problems in children may be due to prenatal maternal stress.
Child behavioural difficulties were assessed using a questionnaire. It included items such as eating, faecal incontinence, attention seeking and dependency, relations with other children, activity, concentration, control, tempers, mood, worries, and fears.
There were no significant moderating effects seen of either the children's gender or socio economic status.
Explanations for stress transfer
The finding of an increased level of behavioural problems in children whose mothers were exposed to higher levels of stressors raises important questions about possible mechanisms of transmission.
The study points to several likely mechanisms that could account for the associations between maternal stress and child behavioural problems. The following mechanisms are mentioned, which are also likely to interact with each other:
Shared environmental factors, such as a hostile environment, to which socioeconomic factors might contribute.
Exposure to increased levels of stressors could increase levels of stress-responsive hormones within the mother, exposing the foetus to these and resulting in an increased latent risk for psychopathology in the child as it develops; antenatal stress and postnatal depression, and other difficulties after birth and whether such difficulties are chronic.
The authors say the study highlights the importance of the prenatal psychological health of mothers in developing country settings in areas of high adversity, both for the well-being of the mother and her offspring. Further research is required to elucidate the mechanisms by which risk may be transmitted from parents to children; however, it is important to note that a potential opportunity for preventive psychological intervention exists.
These findings were reported in an article in the Journal of the American Academy of Child & Adolescent Psychiatry, vol. 49, no. 3, March 2010. The full article is available on www.jaacap.org.
Dr Paul G. Ramchandani is a senior research fellow, Department of Psychiatry, University of Oxford; Professor Linda Richter is executive director, Child, Youth, Family and Social Development, HSRC; Dr Shane Norris is senior researcher, Department of Paediatrics, University of the Witwatersrand; and Professor Alan Stein heads Child and Adolescent Psychiatry, University of Oxford.