Epidemiology of Nausea and Vomiting of Pregnancy: Prevalence, Severity, Determinants, and the Importance of Race/Ethnicity

Anaïs Lacasse; Evelyne Rey; Ema Ferreira; Caroline Morin; Anick Bérard

Disclosures

BMC Womens Health 

In This Article

Abstract and Background

Abstract

Background: Studies that contributed to the epidemiology of nausea and vomiting of pregnancy have reported conflicting findings, and often failed to account for all possible co-variables necessary to evaluate the multidimensional associations. The objectives of this study were to: 1) Estimate the prevalence and the severity of nausea and vomiting of pregnancy during the 1st and the 2nd trimester of pregnancy, and 2) Identify determinants of presence and severity of nausea and vomiting of pregnancy during the 1st and 2nd trimesters separately, with a special emphasis on the impact of race/ethnicity.
Methods: A prospective study including pregnant women attending the Centre Hospitalier Universitaire (CHU) Sainte-Justine or René-Laennec clinics for their prenatal care was conducted from 2004 to 2006. Women were eligible if they were ≥ 18 years of age, and ≤ 16 weeks of gestation. Women were asked to fill out a 1st trimester self-administered questionnaire and were interviewed over the telephone during their 2nd trimester of pregnancy. Presence of nausea and vomiting of pregnancy was based on the reporting of pregnant women (yes/no); severity of symptoms was measured by the validated modified-PUQE index.
Results: Of the 367 women included in the study, 81.2% were Caucasians, 10.1% Blacks, 4.6% Hispanics, and 4.1% Asians. Multivariate analyses showed that race/ethnicity was significantly associated with a decreased likelihood of reporting nausea and vomiting of pregnancy (Asians vs. Caucasians OR: 0.13; 95%CI 0.02-0.73; and Blacks vs. Caucasians OR: 0.29; 95%CI 0.09-0.99).
Conclusion: Our study showed that race/ethnicity was associated with the reporting of nausea and vomiting of pregnancy in the 1st trimester of pregnancy.

Background

Fifty to ninety percent of pregnant women experience nausea and vomiting during their first trimester.[1] In general nausea and vomiting of pregnancy (NVP) appear between the 4th and 6th week of gestational age, with a peak observed between week 8 and 12.[2,3] A more severe form of NVP, known as hyperemesis gravidarum (HG), will also occur in 0.5 to 3 percent of pregnancies and may lead to hospitalisation.[4,5] The aetiology of NVP is poorly understood but NVP could be considered as a multifactorial problem. Proposed theories involve hormonal, vestibular system, gastrointestinal, psychological, hyperolfaction, genetic, and evolutionary factors as possible causes.[6,7]

Studies that contributed to the epidemiology of NVP have reported conflicting findings, and often failed to account for all possible co-variables necessary to evaluate the multidimensional associations.[8,9,10,11,12] For example, whether race/ethnicity influence NVP is not well established. While some studies indicate that incidence of NVP differs according to women's race/ethnicity,[13,14,15,16,17,18] others show no association.[9,19] The fact that none of these studies accounted for potential confounders could partly explain this variability. Moreover, studies did not always have an explicit and valid classification of race/ethnicity, and nearly all of them were done on pregnant women with HG. The reason for the possible association between race/ethnicity and NVP is unknown but it has been proposed that differences between racial/ethnic groups could be accounted by important socioeconomic variables.[12] Only three studies used multivariate analyses to evaluate the association between race/ethnicity and NVP and they show contradictory results. The first one failed to demonstrate a significant relationship between race/ethnicity and vomiting,[12] the second showed that White women had less NVP than Hispanics and Blacks,[11] and the third one showed that Black women had less NVP than whites.[20] The racial/ethnic differences in the reporting of health problems is pivotal in order to find out the reason why patients experience diseases and treatment differently, and to expand approaches for the improvement of public health.[21,22,23] Therefore, a study looking at the association between race/ethnicity and NVP, accounting for possible confounders is warranted.

The first objective of this study was to estimate the prevalence and the severity of NVP during the 1st and the 2nd trimester of pregnancy according to race/ethnicity. Furthermore, we sought to identify the determinants of NVP during the 1st and the 2nd trimester of pregnancy separately, with a special emphasis on the impact of race/ethnicity.

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