Assessing Nausea and Vomiting of Pregnancy

My strong interest in pregnancy lead me to study the most common medical condition during this life stage, nausea and vomiting of pregnancy, during my Nutritional Assessment course at the University of Guelph. I was amazed to learn how two symptoms can have such severe consequences in a woman’s pregnancy and life. This article provides information on the nature of nausea and vomiting of pregnancy (NVP), and methods developed to assess symptom severity, nutritional status and dietary intake.

NVP affects almost 80% of all pregnant women (Goodwin, 2002). Although not usually life threatening, it has a negative effect on a woman’s quality of life during pregnancy (Attard et al., 2002). The severity of NVP ranges between mild nausea and uncontrollable vomiting requiring hospitalization. The most severe form, hyperemesis gravidarum, occurs when NVP progresses to severe vomiting and is characterized by decreased dietary intake (Smithells et al., 1977), dehydration, electrolyte imbalance, and weight loss of >5% of body weight (Fairweather, 1968; Emelianova et al., 1999). Symptoms of NVP usually occur during the first trimester, however, some women experience symptoms for longer (Goodwin, 2002). Assessing the nutritional status and symptoms of nausea and vomiting in pregnant women is important to ensure a healthy pregnancy and optimal quality of life. Symptoms can be assessed using clinical assessment instruments, while anthropometric and dietary measures are used to monitor nutritional status.

The severity of nausea and vomiting can be assessed using a validated questionnaire to quantitatively assess the severity of subjective symptoms (Rhodes et al., 1999). The Rhodes Index of Nausea and Vomiting Form-2 (INV-2) is a validated eight-item self-report instrument that measures the physical symptoms and stress caused by NVP (Rhodes et al., 1984). This instrument has been reformatted to a more efficient, reliable and user-friendly version called the Index of Nausea, Vomiting, and Retching (INVR) (Rhodes et al., 1999). Although this instrument is appropriate for clinical assessment and research, it was created and validated with a respondent sample of people experiencing nausea and vomiting in cancer chemotherapy (Koren et al., 2001). The Motherisk Program in Toronto found the INVR instrument cumbersome and time-consuming (Koren et al., 2001). Motherisk developed the Pregnancy Unique-Quantification of Emesis (PUQE), a self-administered instrument with only three items (length of nausea; number of vomits; number of retching episodes) that can be easily performed in all clinical and research settings (Koren et al., 2002). The PUQE scoring system specific to NVP was validated independently (Koren et al., 2005). The major limitation to both the INVR and PUQE scoring systems is that they cover symptoms occurring in the preceding 12 hours and cannot measure NVP severity for a longer period of time (Lacasse et al., 2008). The modified-PUQE is a validated instrument to quantify symptoms occurring from the start of pregnancy (Lacasse et al., 2008). A study conducted by Koren et al. through the Motherisk counselling telephone line showed modified-PUQE scores to be more severe than the 12-hour PUQE. This can be explained by a recall bias produced by a retrospective evaluation of NVP symptoms (Koren et al., 2004).

Anthropometric measures are used to assess pregnancy weight gain with self-reported height and weight and scale measurements. Self-reported height and weight are used to generate an accurate representation of true pre-pregnancy BMI, that is used as a baseline for measuring weight gain (Brunner Huber, 2007). While self-reported weight is usually underestimated and height is usually overestimated in women of reproductive age, Brunner Huber (2007) found that selfreported measurements used to calculate BMIs accurately classified women into a BMI category as assessed through scale/measured values. The Institute of Medicine (IOM) recommended using BMI measurements to assess weight gain during pregnancy (IOM, 1990). Weight measured using a calibrated, electronic scale should be compared to the IOM recommendations for weight gain within a particular BMI category. Weight is an easy measurement; however, it can be affected by time of day, bladder fullness, and clothing choice (Gibson, 2005). It has been reported that BMI is not a better predictor of maternal and perinatal morbidity than body weight alone (Wolfe, 1991). For now, the IOM guidelines are appropriate as the literature shows that adherence to the guidelines will result in low risk of an adverse pregnancy (DeVader et al., 2007).

Energy intake is assessed by a 24-hour recall (Van Stuijvenberg et al., 1995) using a multiple-pass interviewing technique and food models to assist clients to recall their intake, and to accurately estimate portion sizes (Gibson, 2005). The multiple-pass 24-hour recall is so called because interviewers obtain dietary information through ‘multiple passes’ during the interview process using a quick list, detailed description and a final review (Tran et al., 2000). A limitation to using multiple-pass 24-hour recalls with women is that energy intake is often underestimated (Tran et al., 2000). Twenty-four hour recalls are preferred for woman experiencing NVP as they are physically and emotionally unwell, and there is lower respondent burden compared to maintaining (un)weighed food records (Gibson, 2005).

From researching the development of a questionnaire for assessing the clinical symptoms of nausea and vomiting of pregnancy, I have a greater understanding and appreciation for the time and effort that goes into each questionnaire used by health professionals.

REFERENCES available from Janis Randall Simpson.

Contact

Lindsay Ball, BSc, BASc

Janis Randall Simpson, PhD, RD (advisor)
Unvierstiy of Guelph
E: rjanis@uoguelph.ca