BACKGROUND: Pregnancy nausea and vomiting (NVP) are associated with a wide range of physical and mental changes in the mothers and could affect their adaptation to pregnancy. There is a gap of knowledge regarding the effectiveness of a positive psychology approach counselling on improving coping patterns in women with NVP. OBJECTIVE: This study aimed to determine the effect of supportive counselling with a positive psychology approach on improving coping patterns in women with NVP. METHOD: The current study was a randomized controlled trial on 60 pregnant women who experienced nausea and vomiting in Zanjan a province in the northwest of Iran, 2020–2021. Using four-block random sampling, eligible women were randomly assigned to the intervention and control groups. According to the Seligman protocol, the intervention group received supportive counselling in six sessions of 45 min3 times a week. The revised prenatal coping inventory (Nu PCI) was used to collect data and analyzed using Chi-square, repeated measures ANOVA, and MANOVA at a 95% confidence level. RESULTS: In the counseling group, the mean (SD) of a total score of coping with pregnancy before the intervention was 6.11 (1.31) which increased to 8.40 (1.03) in 4 weeks after the intervention. Based on the MANOVA test with adjusting the number of pregnancies, the mean total score of coping with pregnancy was statistically significant 4 weeks after the intervention compared with the control group (Adjusted mean difference (AMD) = -1.84, CI95% -2.36, -1.32, p = 0.001). CONCLUSION: The use of positive psychology in supportive counselling improved the coping of mothers suffering from nausea and vomiting during pregnancy. It is recommended that this approach be incorporated into prenatal care to promote the health of pregnant women. TRIAL REGISTRATION: The study was registered at the Iranian Registry of Clinical Trials website under the code IRCT20150731023423N17. Registration date: 2020–10-31, Expected recruitment start date: 2020–11-01. IRCT Id: IRCT20150731023423N17. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12884-022-04603-4.
Effects of supportive counseling using a positive psychology approach on coping patterns among pregnant women with nausea and vomiting