A detailed flow-chart of the recruitment, the refusals, and the follow-up is presented in Figure . Our study population consisted of 367 pregnant women recruited between 2004 and 2006. Maternal characteristics including race/ethnicity and NVP status of the study population are presented in Table . In the 1st trimester of pregnancy, 78.5% of women reported NVP. In this group, 52.2% experienced mild NVP, 45.3% moderate NVP, and 2.5% severe NVP. In addition, 26% of pregnant women reporting NVP also reported excessive salivation during the 1st trimester of pregnancy, and the majority of them were distressed by this situation (Table ). When asking what women had used in their first trimester to ease nausea and vomiting, 20.4% of them reported having used medications, and 17.9% non-pharmacological methods. As for the 2nd trimester of pregnancy, 40.1% of women reported NVP (data not showed). Among them, 63.3% experienced mild NVP, 35.9% moderate NVP, and 0.8% severe NVP. Intensity of nausea and excessive salivation experience was similar to what had been reported in the 1st trimester of pregnancy. Globally, in our study population, 41.1% of women reported NVP in the 1st trimester of pregnancy only, 1.3% in the 2nd trimester of pregnancy only, and 38.9% in both of these two gestational periods.
Study population recruitment and follow-up. *Maternal and gestational age at inclusion.
Maternal characteristics and NVP status during pregnancy.
As showed in Table , the reporting of NVP symptoms was not significantly different between racial/ethnic groups (p = 0.06). However, pairwise comparisons showed that NVP was significantly more prevalent in Hispanic (94.1%) women compared to Asians (60%; p < 0.05). Proportion of women reporting excessive salivation in the 1st trimester of pregnancy was higher in Blacks (79.2%) than in Caucasians or Hispanics (Caucasians 19.6%, Hispanics 35.7%; p < 0.05).
Prevalence and severity of NVP in the 1st trimester of pregnancy according to race/ethnicity.
Multivariate analyses [see Additional file 1
] showed that race/ethnicity (Asians vs. Caucasians, and Blacks vs. Caucasians), household income (40000–79999 vs. < 40000 cdn$/yr), and OC use in the six months before pregnancy were significantly associated (p < 0.05) with a decreased likelihood of reporting NVP. In the 303 multigravida women, nausea in previous pregnancies was significantly associated with an increased likelihood to report NVP in the 1st
trimester of pregnancy (OR: 3.17; 95%CI 1.25–8.03).
The 2nd trimester interview data were available for 319 of the 367 (87%) women of the study population. Reasons for which women were excluded from the 2nd trimester analysis are presented in Figure . Multivariate models (not showed in table form) showed that greater gestational age at the 2nd trimester interview (OR: 0.89; 95%CI 0.79–1.00), exercise during the 1st trimester of pregnancy (OR: 0.49; 95%CI 0.24–0.98), coffee drinking before pregnancy (OR: 0.32; 95%CI 0.12–0.89), and weight gain during the 1st trimester (OR: 0.73; 95%CI 0.61–0.88) were significantly associated with a decreased likelihood of reporting NVP in the 2nd trimester of pregnancy. Presence of NVP during the 1st trimester of pregnancy (OR: 14.80; 95%CI 4.48–48.95), and female foetus gender (OR: 2.08; 95%CI 1.11–3.90) were significantly associated with an increased likelihood of reporting NVP in the 2nd trimester of pregnancy. Race/ethnicity was not a determinant of NVP in the 2nd trimester of pregnancy.
Multivariate analyses [see Additional file 2
] showed that being born outside Canada, using medications to ease NVP, using non-pharmacological methods to ease NVP, and parity (2 or more children vs. 0), were significantly associated (p < 0.05) with more severe NVP symptoms during the 1st
trimester of pregnancy. Race/ethnicity was not found to be associated with NVP severity in the 1st
trimester of pregnancy.