Demographic and Baseline Data. Of the 34 women who were eligible for the study, 28 were randomized to study groups (16 in the Breezing™ and 12 in the Control groups; Figure 1). All 28 women completed the entire study. The median study duration for the control and Breezing™ groups was 13.4 (12.9, 14.0) and 13.4 (IQR: 13.3, 14.8) weeks, respectively (Kruskal-Wallis H test, χ2=1.2, p=0.27). The mean gestational age was 14.8±2.3 weeks at study visit 1, 17.9±2.7 weeks at study visit 2, 20.2±2.5 weeks at study visit 3, 22.4±2.4 weeks at study visit 4, 24.3±2.7 weeks at study visit 5, 26.7±2.8 weeks at study visit 6, and 28.9±2.6 weeks at study visit 7. Complete demographic data and baseline data are provided in Table 1. Body mass index (BMI) categories of the women at the initial study visit were equally distributed with 35.7% (n=10) classified as normal weight, 35.7% (n=10) as overweight, and 28.6% (n=8) as obese. The distribution across groups by BMI category did not differ (χ2=3.5, p=0.17). Figure 2 provides the distribution of initial study visit BMI category for the two study groups and the entire cohort.
Intervention Effect on GWG. Table 2 summarizes the rate and total GWG for the study participants. Despite the Breezing™ group having a greater initial weight, both groups experienced similar overall rates of [F(1,24)=-2.0, p=0.17] and total [F(1,24)=1.6, p=0.22] GWG. Compared to the control group, the Breezing™ group had a significantly higher rate of GWG during the second half of the study (F(1,24)=8.15, p=0.01), but not during the early half of the study [F(1,24)=0.56, p=0.46]. There was no difference between groups in total GWG during the first half of the study [F(1,24)=0.38, p=0.54]; however, the Breezing™ group gained significantly more (total GWG) than the Control group during the second half of the study [F(1,24)=5.1, p=0.03].
REE. Data obtained from the Breezing™ device are presented in Table 3. There were non-significant variations in REE throughout the study [F(6,60)=0.14, p=0.99]. 80% (n=12/15) of women had an increase in REE between the second and third study visit (mean GA: 18 to 20 weeks) with increases in REE ranging from 10 to 350 kcal/day. The differences between the remaining study visits were almost evenly split among women who experienced an increase (range: 53-63%) or a decrease (range: 38-50%) in REE. Early changes in REE (72±211 kcals) were relatively small but late changes (128±294 kcals) were nearly twice that of early changes. The mean overall change in REE was 200±316 (range: -340 to 950) kcals. There was an 11.5% increase in total REE between the first and last study visits among the Breezing™ group participants.
Association between REE and Rate of GWG. Early changes in REE were not associated with early changes in the rate of GWG (r=-0.26, p=0.33). Similarly, there was no association between late changes in REE and late changes in GWG (r=-0.18, p=0.55). Likewise, there was no relationship between overall changes in REE and overall changes in GWG (r=0.01, p=0.96). However, there was a positive correlation between early changes in REE and late changes in the rate of GWG such that greater increases in REE early in the second trimester were related to greater rate of GWG in the latter half of the second trimester (r=0.54, p=0.03).
Macronutrient Composition. There were no statistically significant differences for any of the baseline dietary intake data (Table 4). The early, late, and overall changes in consumption of the macronutrients among the two study groups are provided in Table 5. Overall (mean diff=-349.1±150.8, 95% CI: -660.3 to -37.9, p=0.03) and late (mean diff=-379.9±143.9, 95% CI:-676.9 to -82.9, p=0.01) mean differences in changes in energy consumption were significantly different between the Breezing™ and Control groups. Overall changes in protein were mildly different between Breezing™ and Control group participants (mean diff=-22.5±11.0, 95% CI: -45.2 to 0.3, p=0.05). Likewise, late changes in protein decreased slightly more for the Breezing™ group when compared to the Control group (mean diff=-23.2±11.2, 95% CI: -46.3 to 0.0, p=0.05). Early changes in protein were marginally increased in the Breezing™ group relative to the Control group (mean diff=20.3±10.2, 95% CI: -0.7 to 41.3, p=0.06). There were no statistically or marginally significant differences for overall, late, and early changes in carbohydrates and fat.
Association between REE and Macronutrient Composition. Overall changes in REE were not correlated with overall changes in energy (r=0.24, p=0.38), fat (r=0.25, p=0.34), protein (r=0.36, p=0.17), or carbohydrate (r=0.03, p=0.91) consumption. Evaluation of time-specific changes in macronutrients with time-specific changes in REE revealed significant correlations between early changes in REE and overall changes in carbohydrate intake (r=0.58, p=0.02) and a trending significant correlation with overall changes in energy intake (r=0.46, p=0.07).