Background: There is current interest in symptoms during pregnancy, but yet little is known about their prevalence and how often they are experienced across pregnancy. The reasons why some women experience more symptoms or experience them more often than others has received limited research attention.
Objective: To document the prevalence and frequency of 27 pregnancy symptoms and to systematically investigate, cross-sectionally and prospectively, the effect of psychosocial factors on the prevalence and frequency of these symptoms, while controlling for biomedical factors.
Methods: Four hundred and seventy-six nulliparous Scandinavian women who attended routine prenatal care in Uppsala county, Sweden, were studied six times during pregnancy (gestational weeks 10, 12, 20, 28, 32, and 36).
Results: The prevalence of symptoms was high, but only a smaller portion of these symptoms were experienced frequently. Psychological stress particularly contributed to the prevalence and frequency of concurrent symptoms and predicted symptoms up to 16 weeks later, independent of medical risk, smoking, and weight gain.
Conclusions: Prevalence rates may be inflated, because many symptoms were experienced only 'occasionally' during each of the 4-week periods we sampled. By examining how frequently symptoms were experienced, we gained an indication of which symptoms are more likely to be bothersome or intrude upon daily activities. Psychosocial variables accounted for individual differences in symptom reports after taking biomedical factors into account. Attention to psychosocial variables in future studies will aid in our understanding of the etiology of pregnancy symptoms.