Pregnancy complications and birth outcomes among women experiencing nausea only or nausea and vomiting during pregnancy in the Norwegian Mother and Child Cohort Study

BACKGROUND: To compare pregnancy complications and birth outcomes for women experiencing nausea and vomiting in pregnancy, or nausea only, with symptom-free women. METHODS: Pregnancies from the Norwegian Mother and Child Cohort Study (n = 51 675), a population-based prospective cohort study, were examined. Data on nausea and/or vomiting during gestation and birth outcomes were collected from three questionnaires answered between gestation weeks 15 and 30, and linked with data from the Medical Birth Registry of Norway. Chi-squared tests, one way analysis of variance, multiple linear and logistic regression analyses were used. RESULTS: Women with nausea and vomiting (NVP) totalled 17 070 (33 %), while 20 371 (39 %) experienced nausea only (NP), and 14 234 (28 %) were symptom-free (SF). When compared to SF women, NVP and NP women had significantly increased odds for pelvic girdle pain (adjusted odds ratio, aOR, 2.26, 95 % confidence interval, 95 % CI, 2.09–2.43, and aOR 1.90, 95 % CI, 1.76–2.05, respectively) and proteinuria (aOR 1.50, 95 % CI 1.38–1.63, and 1.20, 95 % CI 1.10–1.31, respectively). Women with NVP also had significantly increased odds for high blood pressure (aOR 1.40, 95 % CI 1.17–1.67) and preeclampsia (aOR 1.13, 95 % CI 1.01–1.27). Conversely, the NVP and NP groups had significantly reduced odds for unfavourable birth outcomes such as low birth weight infants (aOR 0.72, 95 % CI 0.60–0.88, and aOR 0.73, 95 % CI 0.60–0.88, respectively) and small for gestational age infants (aOR 0.78, 95 % CI 0.73–0.84, and aOR 0.87, 95 % CI 0.81–0.93, respectively). CONCLUSIONS: We found that women with NVP and NP are more likely to develop pregnancy complications, yet they display mostly favourable delivery and birth outcomes. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12884-015-0580-6) contains supplementary material, which is available to authorized users.