Nausea and vomiting in pregnancy and the impact upon dietary intakes and birth outcomes – a study performed in the Norwegian Mother and Child Cohort Study

Background: Nausea and vomiting during pregnancy (NVP) is often experienced by women during gestation. Most studies report up to 80% of women experience one or both of these phenomena, and symptoms of NVP have been recorded from 2000 B.C. to the present time. Favorable birth outcomes are often reported for pregnancies experiencing NVP whilst simultaneously having negative effects upon quality of life of the expectant mother during pregnancy. At the present time the etiology of NVP is unknown, yet there are many hypotheses from different fields of science and with various explanations addressing why NVP occurs, and how it may be triggered in the body. It is also common during periods of NVP for women to alter their diet, whether it is owing to a pregnancy-related craving or aversion to certain foods or by the inability to eat as desired owing to the associated symptoms. The aim of this study was to explore the occurrence of nausea alone or NVP in the Norwegian population, and to explore the dietary changes that may occur to pregnant women experiencing these symptoms. Furthermore, the reported favorable birth outcomes associated with NVP were to be assessed. Subjects and Methods: Using data collected in the Norwegian Mother and Child Cohort study (MoBa), maternal demographic data and dietary intakes were cross-referenced with those reporting nausea alone and NVP. The MoBa cohort contains many variables related to mother and child, and these provided data regarding the pattern of nausea and NVP, as well as birth outcomes. Statistical methods were used to test for associations between the variables. Results: In total, 62 416 women were included in the study sample. Of these, 17 185 women (27.5%) experienced no symptoms, 27 642 women (44.3%) experienced nausea only, and 17 589 women (28.2%) experienced NVP. The NVP women experienced the least gestational weight gain, whilst simultaneously having the largest dietary intake of all macronutrients. A larger proportion of the no symptom group started to eat probiotic foods and chocolate during pregnancy. The NVP group represented the largest proportion of those beginning to eat foods rich in sugar, foods rich in sour/salt taste, milk, fruit, vegetables, and sugared soft drinks. The nausea and NVP group had more babies born large for gestational age (LGA), and the no nausea group had more small for gestational age (SGA) babies. The no nausea group gave birth to a higher number of male babies, as well as babies with the lightest mean birth weight. Babies born to the nausea group of women were the heaviest of all three groups. Conclusion: The results from the study show that women experiencing nausea or NVP have a significantly different dietary profile compared to those women without symptoms. Additionally, the nausea and NVP women had a higher proportion of birth outcomes such as birth weight and length of gestation that were within normal parameters, supporting studies reporting nausea and NVP to be associated with favorable birth outcomes. Questions regarding the different dietary habits of the three groups, especially in association with probiotic foods, water, salty foods and chocolate intakes, should be addressed in future studies.