[Nausea and vomiting as evolutionary mechanisms of the complex adaptation reaction to pregnancy]

Nausea and vomiting during pregnancy (NVP) constitute a frequent and often highly unpleasant syndrome during the sensitive period of early pregnancy, which has been intensively investigated. However, many questions remain unanswered, particularly the counterintuitive association with a better pregnancy outcome. Under these circumstances our functional concept to interpret NVP as an evolutionary mechanism of complex adaptation to early pregnancy seems promising.

In this cross-cultural study data were collected from 565 mothers, who had given birth recently in South Africa, Guatemala and Germany, using a standardised questionnaire interview.

There was a cross-culturally similar prevalence and clinical presentation of NVP, showing a high degree of subjective suffering. We found evidence supporting a multifactoral aetiology of biological, psychological and sociological factors. Likewise, NVP seems to have multiple effects, concerning nutrition, behaviour, perception, psychology and social support.

Our new and previously existing data support the idea that NVP has been selected for by evolution, as a functional adaptation to vulnerable early pregnancy, which benefits mother and child. This assumption is supported by the correlation of NVP with a better foetal prognosis, the cross-culturally high prevalence and a favorable relation of low biological costs versus high effects. The benefit of NVP could be realised by nutritional change, increased social support, more passive and careful behaviour, earlier recognition of pregnancy and a positive influence on foetal development. To understand the functionality of NVP, one needs to consider the complex somato-psychoemotional interplay in the context of an environment of evolutionary adaptedness (EEA).