Background
There are recognised limitations to the measurement of dietary intake in clinical or epidemiological research. Commonly used tools including food frequency questionnaires (FFQ), 24-h dietary recalls and dietary records can result in misreporting (low or high reporting) of dietary intake in comparison with gold-standard measures such as doubly labelled water and 24-h urinary nitrogen excretion [
1]. The prevalence of misreporting varies but is estimated at ~ 30% for under reporting of energy intake and ~ 10% for over reporting of energy intake in the general adult population [
2]. Misreporting also varies depending on the dietary assessment tool used with a lower level of low energy reporting for multiple 24-h recalls compared with a FFQ [
3]. Misreporting is related to characteristics including adiposity, socioeconomic status and education, age, gender, psychological status such as depression or poor body image, or health-related activities such as smoking or dieting [
2,
4]. Misreporting of energy intake could reflect intentional under recording which can be related to social desirability bias. In particular, low energy reporting may result from biasing of reported intake towards foods deemed more appropriate [
4,
5] with a lower intake of unhealthier foods high in fat and sugar or unhealthy eating habits resulting in an overall lower diet quality [
4]. It may also be related to failure to record accurate food intake due to recall bias or memory lapses, poor awareness of quantities or types of foods eaten [
2], the inconvenience of reporting, or reporting an incomplete or simplified version of what is consumed secondary to inaccurate portion size estimation [
6].
The misreporting of dietary intake, particularly if systematic and non-random, can result in incorrect assessments of the relationships between dietary components and clinical outcomes. The common under reporting of energy intake or specific dietary components in obesity may also result in a specific bias in studies investigating the relationship between the aetiology and consequences of obesity. Stronger associations between diet, obesity or obesity-associated health conditions or biomarkers of diet or obesity-related health have been previously reported in adequate compared to under reporters of energy intake [
7,
8].
Ensuring adequate dietary intake during pregnancy is crucial for optimising maternal, fetal, and infant outcomes [
9,
10]. This is important with regards to ensuring micronutrient adequacy and preventing excess energy and macronutrient intake. The identification of women who misreport energy intake in pregnancy is important in identifying any associations between maternal antenatal diet and subsequent health outcomes. This is also relevant in overweight and obese pregnant women as they are more likely to have a higher prevalence of under reporting of energy intake [
11], and an increased risk of adverse pregnancy and birth complications. [
12] Furthermore, children born to women who are overweight or obese have a higher prevalence of childhood and adult obesity, and obesity-related conditions [
13,
14]. However, there is limited literature examining the characteristics of pregnant women who misreport energy intake. While psychological characteristics are associated with under-reporting in the general population [
4,
15], there is minimal examination of depression [
16] and no examination of the contribution of anxiety, body image status or dieting behaviour to misreporting in pregnancy. There is also limited and contradictory literature examining changes in misreporting status across pregnancy [
17,
18], it being unclear if there is a true reduction in energy intake related dietary restriction or to a higher level of energy misreporting.
The aim of this study was to perform a comprehensive assessment of energy misreporting status across two time-points in pregnancy (early and late pregnancy) in a large population of overweight and obese women. Specifically, we aimed to assess the demographic, behavioural and psychological characteristics of overweight and obese pregnant women who misreported energy intake or who had changes in energy misreporting status across pregnancy.
Discussion
We report for the first time the association of behavioural and psychological factors with energy misreporting status in a large population of overweight or obese women across pregnancy. At 10–36 weeks gestation under reporting of energy intake was present in up to 50% of women and was independently related to BMI, SEIFA, prior dieting behaviour and depression. The level of under reporting was higher in late pregnancy in comparison to early pregnancy. Diet quality was lower among women who under reported energy intake. We reported a low prevalence of women who over reported intake (0.2–2.3%), in contrast to other reports of up to 12% during pregnancy [
11,
16].
As previously reported, under reporting of energy intake was present in a third of overweight or obese women at study entry [
16,
37]. As not all overweight and obese women misreport energy intake it is important to identify characteristics that may be predictive of misreporting status. Under reporting of energy intake was more common among obese women compared with overweight women [
11,
16,
37] consistent with general population data [
2]. The association of low socioeconomic status or education with under reporting of energy intake in the general population or in pregnancy has also been previously reported, and may reflect poor literacy skills [
2,
37]. Alternatively, a positive association has also been reported between education and under reporting [
43] which may reflect those with a greater knowledge about healthy eating being more prone to selective misreporting. Women may also experience pressure and guilt in relation to achieving an optimal diet during pregnancy [
44] which increases as pregnancy progresses and may be compounded by socioeconomic status reflecting poorer health literacy and differences in knowledge and attitudes towards nutrition [
45].
We report a range of behavioural or psychological factors that are independently associated with under reporting of energy intake during pregnancy. Specifically, we have identified an independent association between risk of depression and a lower prevalence of under reporting of energy intake in late pregnancy. This is in contrast to prior reports, in which there was no association between risk of depression and low energy reporting, but positive associations with high energy reporting in the second trimester of pregnancy [
16]. We found no association between symptoms of anxiety and energy misreporting, which is in contrast to reports from the general population [
46]. Increased dieting behaviour prior to pregnancy, greater body dissatisfaction and less dissatisfaction with weight or shape were all associated with a higher level of under reporting of energy intake, in keeping with general population data [
4,
47]. However, weight and shape satisfaction associations were attenuated in the logistic regression models indicating a likely indirect relationship between body image and to energy reporting through its relationship with BMI.
There is limited and conflicting literature assessing changes in energy reporting status across pregnancy. A lower level of under reporting of energy intake later in pregnancy assessed by 24-h recall was reported in
n = 490 pregnant Indonesian women [
17]. However, others have reported a higher level of under reporting of energy intake later in pregnancy in 12 women, in the only study utilising the gold-standard assessment of energy expenditure of doubly labelled water [
18] consistent with our results presented here. The reason for the higher under reporting occurring at week 36 in our current study is unclear. It was not possible to identify characteristics of women who modified their energy reporting status across pregnancy due to the small event number with the exception of age and BMI. It may be related to factors such as increased time pressures or the effect of weight increasing as pregnancy progresses. We have also previously reported a reduction in depression across pregnancy in this cohort [
23]. Given that we reported higher depression was related to lower under reporting on logistic regression analysis, the higher under reporting may be a reflection of this previously observed lower level of depression. While under reporting of energy intake commonly reflects inadequate reporting of dietary intake, it may also reflect an actual restriction in food intake. This may be particularly relevant in overweight or obese women during pregnancy as an attempt to prevent excess weight gain [
48]. However, while women who under reported their energy intake at 36 weeks were more likely to report a history of multiple dieting attempts in the previous 12 months, we did not assess if women perceived themselves to be under any dietary restraint during pregnancy itself. In early pregnancy, under reporting of energy intake may also reflect dietary intake secondary to nausea or food aversions. We didnot specifically measure these issues as many women attended the trial entry visit in the second trimester where some of these symptoms may have abated. As these symptoms may affect a large proportion of women (up to 72% in a Norwegian cohort study of
n = 51,675 women) [
49], it is crucial to report this in future research assessing dietary misreporting during pregnancy.
We also identified that women who under report energy intake have a subtly poorer diet quality, largely reflecting reduced core food group intake, as has previously been reported [
37]. This is in contrast to data from the general population where under reporters of energy intake have improved diet quality [
4], more optimal dietary intake by dietary pattern analysis, [
50] or micronutrient densities [
2,
7], a lower proportional intake of fat, [
4] and lower consumption of non-core foods [
4]. Our study comprised only women who were overweight or obese and it is possible that this precluded an accurate assessment of changes in dietary intake across all energy reporting groups. Alternatively, if low energy reporting in pregnancy reflects an actual reduction in food intake then a subset of overweight and obese pregnant women are limiting their dietary intake, which in turn potentially impacts their diet quality.
Our study has focused on women who were overweight and obese, which limits therefore the generalisability of our results. We note that the self-reporting of dietary intake data is associated with a degree of inherent measurement errors [
51]. In particular, the use of FFQ is associated with a higher level of under energy reporting of intake, when compared with other tools of dietary assessment, such as multiple 24-h recalls. [
3]. This may reflect a number of underlying factors including measurement error relating to recall bias, categorisation of portion size and food items lists that may not reflect a changing and diverse food supply [
52]. However, the use of the FFQ is more practical and feasible for use in a large scale clinical trial such as ours, and for ranking individuals in large epidemiological or clinical trials. We note the different recall periods used for the FFQ (12 months versus 8 weeks). This may result in capturing a combination of pre-pregnancy and pregnancy dietary intake for the trial entry FFQ in comparison to only pregnancy dietary intake for the 36 week questionnaire which may introduce bias into our dietary information. SEIFA is also an estimate of socioeconomic status that may not accurately reflect individual or familial disadvantage. [
20] The influence of family income, education or occupation on energy misreporting in pregnancy should be considered in future studies. The strengths of this study include the large sample size, a comprehensive assessment of women’s psychological wellbeing and assessment at two time points across pregnancy.
Our detailed assessment of demographic, behavioural and psychological characteristics has identified factors independently associated with energy misreporting across pregnancy. It is important to identify women who are at high risk of energy intake under reporting across pregnancy, who may be suitable for a more intensive and tailored intervention during pregnancy. Furthermore, if under reporting of energy intake in pregnancy reflects a true reduction in food intake, this also highlights a proportion of overweight and obese pregnant women who may have suboptimal dietary intake, and who warrant specific attention for improving their diet quality and nutrient adequacy.
Acknowledgements
The following individuals and institutions (except where indicated, in Adelaide, South Australia) participated in the LIMIT Trial:
Steering Group: JM Dodd (Chair), D Turnbull, A McPhee, RM Grivell, C Crowther, M Gillman (Obesity Prevention Program, and Harvard University, Boston, Massachusetts, USA), G Wittert, JA Owens, JS Robinson.
Co-ordinating Team: JM Dodd, A Deussen, RM Grivell, L Yelland, L Moran, C Cramp, A Newman, L Kannieappian, S Hendrijanto, M Kelsey, J Beaumont, C Danz, J Koch, A Webber, C Holst, K Robinson, S Zhang, V Ball, K Ball, H Deussen, N Salehi, R Bartley, R Stafford-Green, S Ophel, M Cooney, M Szmeja, A Short, A Melrose, S Han, I Mohamad, L Chapple.
Statistical Analyses: L Yelland.
Serious Adverse Events Committee: RM Grivell, J Svigos, V Bhatia, N Manton.
Writing Group: JM Dodd, D Turnbull, A McPhee, A Deussen, RM Grivell, L Yelland, C Crowther, G Wittert, JA Owens, JS Robinson.
Collaborating Hospitals (total number of women recruited from each site in parentheses). *Indicates named associate investigator for the NHMRC grant.
• Flinders Medical Centre (South Australia) (669): J McGavigan*, R Bryce, S Coppi, C Fanning, G Hannah, M Ignacio, H Pollard, F Schmidt, Y Shinners.
• Lyell McEwin Hospital (South Australia) (505): G Dekker*, S Kennedy-Andrews, R Beaven, J Niven, S Burgen, J Dalton, N Dewhurst, L Forst, V Mugg, C Will, H Stone.
• Women’s and Children’s Hospital (South Australia) (1,038): JM Dodd, JS Robinson, A Deussen, C Crowther*, C Wilkinson*, H Purcell, J Wood, D Press, K Ralph, S Donleavy, S Seager, F Gately, A Jolly, L Lahnstein, S Harding, K Daw, M Hedges, R Fraser-Trumble.
We are indebted to the 2,212 women who participated in this randomised trial.