Introduction Although perinatal distress is acknowledged as a burdening condition for pregnant women, its effects on pregnancy are not well known. This study was conducted to increase knowledge regarding the effects of distress on pregnancy-related problems. The study also assessed women's need for sick leave and increased prenatal care due to distress, and the effects of weak social support and dissatisfaction with their partner relationships. Methods In total, 2523 women were screened for perinatal distress three times during pregnancy in this quantitative cohort study. Structured psychiatric interviews were conducted following the screening, with 562 of the participants. Data from participants' pregnancy records were also analysed. The study was conducted in primary healthcare centres in Iceland after receiving approval from the Icelandic National Bioethical Committee. The main outcome measures were pregnancy problems, sick leave issued and prenatal service needs. Results Data from 503 women were analysed. The perinatal distress group (PDG) was significantly more likely than was the nondistressed group (NDG) to experience fatigue, vomiting and pelvic pain after controlling for background variables. Distressed women who reported weak family support experienced symptoms of nausea and heartburn. The PDG needed more frequent prenatal care than did the NDG and was issued sick leave for up to 42 days longer. Dissatisfaction in the partner relationship and with the division of household tasks and childcare was strongly associated with distress, the development of complications and the need for sick leave. Discussion Identification of perinatal distress by midwives and other healthcare professionals is important, since distress may be linked to women's complaints of fatigue, vomiting, pelvic pain and need for prolonged sick leave, and additional prenatal care services will be needed. Perceived dissatisfaction in the partner relationship and with the division of household tasks should also form part of clinical practice and assistance provided.