Discordance between physical symptoms versus perception of severity by women with nausea and vomiting in pregnancy (NVP)

Background Nausea and vomiting in pregnancy (NVP) is a multifaceted condition that affects more than half of pregnant women and can range in severity from mild nausea to severe dehydration. Presently physicians evaluate mostly physical symptoms of NVP in trying to assess the severity of the condition. The objective of this study was to investigate how factors, other than the physical morbidity of nausea and vomiting, influence self-perception of NVP by affected women. Methods Five hundred women with NVP calling a 1–800 NVP Healthline were asked to rate their NVP severity and report their nausea duration and number of vomiting/retching episodes. Results Nausea and vomiting/retching correlated significantly but very poorly with self-assessment of NVP severity. There was also a correlation between nausea duration and vomiting/retching frequency however the correlations were weak and overall physical symptoms could only explain 14% of the variability of women's feelings and perceptions through multivariate analysis. Conclusions Physical symptoms weakly correlate with self-assessment of NVP severity. Other aspects of this condition, most probably psychosocial, influence women's perception of NVP severity.


Introduction
Descriptions of nausea and vomiting of pregnancy (NVP) date back to writings from the second century AD [1]. NVP affects up to 80% of pregnant women to greater or lesser degrees [2]. Approximately 50% of women have nausea and vomiting, whereas approximately 30% have only nausea [2]. Symptoms are usually self-limited in duration (i.e. to 7-12 weeks gestation), although 9% of women continue to have symptoms beyond 20 weeks [2]. Fewer than 1% of pregnant women develop hyperemesis gravidarum (HG) characterized by severe physical symptoms and/or medical complications (e.g. dehydration, electrolyte imbalance) requiring admission to hospital [2]. Even when the condition is less severe, symptoms can cause considerable distress and temporary disability. In a study that assessed the quality of life of women with NVP, nearly 50% of employed women reported that work efficiency was reduced by this problem, and as many as 25% required time off from work [3].
NVP has a spectrum of severity that can range from mild, occasional nausea to constant nausea with frequent vom-iting. Traditionally, health care providers tended to manage the physical symptoms of NVP, however it has become evident recently that the impact of NVP on the quality of life of the woman and her family far exceeds the extent of physical morbidity [4]. It is a multifaceted condition and its severity can be aggravated by other domains even when physical symptoms are mild. Other components may include emotional, psychosocial, environmental, nutritional and occupational disabilities [4]. Presently it is not known to what extent physical symptoms determine (or fail to do so) women's overall perception of severity of their condition.
The objective of this investigation was to assess whether severity of physical symptoms of NVP correlates with the woman's overall perception of the severity of her condition.

Methods
Women calling the NVP Helpline at the Motherisk Program in Toronto, were asked to undergo a structured interview to develop a health-related quality of life instrument for this condition. Women were included in the study if they had NVP, called within the first 20 weeks of gestation, understood English and were able to speak on the phone.
Women were excluded if they had medical conditions that may have affected their NVP symptoms such as hyperthyroidism, diabetes, lupus, heart and kidney diseases and gastro-intestinal problems, were greater than 20 weeks gestation or did not consent to participate in the study.
Using the questionnaire women were asked to rate their overall perception of severity of NVP as mild, moderate or severe. In addition, they were asked to report their daily nausea duration and vomiting/retching frequency for the past week. Recent data from our group has shown very high recall within a week. As shown by us and others, the duration of daily nausea and frequency of vomiting/retching are the most predictive values for overall physical severity of NVP [5]. The protocol was approved by our hospital's research ethics board and verbal consent was obtained from the participants.
Five hundred women were eligible and consented. The mean age of the participants was 31.1 ± 4.5 years while the mean gestational age was 9.5 ± 2.6 weeks. Eighty one percent (407) were Caucasian, 95 % (477) were married, 67% (335) had a college/university degree, 71% (357) were full-time workers and 98% (485) were non-smokers. Forty four percent (218) used anti-emetic drug therapy and one third (162) used non-drug treatment with the two modalities not mutually exclusive.
Baseline information was also collected about maternal demographics, medical and obstetric histories, as well as exposure to other medications, chemicals, cigarettes and/ or recreational alcohol or drugs.
The correlation between women's perception of NVP severity and nausea duration or vomiting/retching frequency was studied by least square linear regression. The correlation between nausea duration and vomiting/retch-  ing frequency was studied in a similar way. A multivariate analysis was also employed in this study whereby nausea duration and vomiting/retching frequency were independent variables and NVP severity was the dependent variable.

Results
Forty five percent (225) of women rated themselves as experiencing severe NVP, while 49% (244) classified themselves as suffering from moderate and 6.2% (31) suffering from mild NVP (figure 1). Figures 2 and 3 show the distribution of severity of nausea duration and vomiting/retching frequency. As illustrated the majority of women reported having nausea 'always' and vomiting/retching '2-5 times a day'. The proportions of women who rated their NVP severity and reported their duration of nausea and frequency of vomiting/retching are shown in table 1.
The correlation coefficients of NVP severity with nausea duration and with vomiting/retching frequency were statistically significant, but weak. The duration of nausea contributed only 6.25% (r 2 = 0.0625) of the variability of women's perception of severity, whereas the frequency of vomiting/retching contributed only 9% (r 2 = 0.09) to women's perception. The correlation between nausea duration and vomiting/retching frequency was 0.140. These are shown in table 2.
Because the relationship between nausea duration and vomiting/retching frequency was significant, but poorly correlated, a multiple regression analysis was employed in this study. Multi-linear regression analysis revealed that both nausea and vomiting/retching independently predicted women's perception of severity (p < 0.001 for each). The regression analysis of nausea and vomiting/ retching contributed only 14.2% (r 2 = 0.142) of the variability of women's perception of NVP severity (table 3).

Discussion
The present study introduces quantitative evidence to previous impressions, that the physical symptoms of NVP cannot, by themselves, describe and qualify the severity of the condition as felt by the woman.
In this study, 500 women rated their perception of severity of NVP while separately also reporting their physical symptoms including duration of nausea and episodes of vomiting/retching. The perception of NVP severity was significantly but very weakly correlated with both physical symptoms of nausea and vomiting/retching. The physical symptoms attributed only 14% to the variability of women's perception. This indicates that physical symptoms are weak predictors of NVP severity as perceived by the pregnant woman herself.
Psychosocial and emotional morbidity are evident in NVP and have been reported by us, among NVP patients [4]. Women commonly reported on depression, isolation and despair [4]. Women also reported that support and validation of their NVP by family members and physicians had a positive effect on symptoms and they felt reassured by their partner and friends.
Nutritional status can also influence the perception of severity. Women who eat frequent, small meals reported feeling much better than women who did not [6]. An

Figure 3
Vomiting/retching frequency of 500 women Five hundred women reported their daily frequency of vomiting/ retching in pregnancy during the past week on the following scale: having vomiting/retching greater than 5 episodes per day, 2-5 episodes per day, one episode per day or no episode of vomiting/retching.