**2. Material and Methods**

The study analyzed 346 questionnaires filled in correctly by pregnan<sup>t</sup> women (157 in the second trimester and 189 in the third). The data were directly distributed among pregnan<sup>t</sup> women who participated in activities for pregnan<sup>t</sup> women organized within antenatal classes or in fitness clubs in Szczecin and Warsaw, Poland. The survey was anonymous and conducted only in places where consent was obtained. The respondents consisted only of volunteers. In each case, the survey supervisor presented the purpose and scope of the research to the respondents and instructed them on how to complete the questionnaires. The method "pen and paper" was used in the study. The respondents were given unlimited time to fill in the questionnaires.

The analysis excluded three questionnaires in which the first trimester of pregnancy was declared. Furthermore, the questionnaires which were not filled in completely or were filled in incorrectly were rejected (contrary to the instructions). 400 questionnaires were distributed to women, 346 of which were fully and properly completed. 21 questionnaires were incompletely or incorrectly filled in, and 29 questionnaires were not returned. The project was approved by a local Bioethics Committee.

The age of the respondents was 30.4 ± 3.6 years. Over 90% of study participants were college graduates (91.9%), 8.1% graduated from high school, 81.5% were married, 17.3% were single, while 1.2% were divorced. Furthermore, 88.2% were childless, 10.1% had 1 child and 1.7% had 2 or more children.

The tool used for assessment of PA was the Pregnancy Physical Activity Questionnaire-Polish version (PPAQ-PL) [32–34]. The original version of PPAQ was designed by Chasan-Taber et al. [35]. The questionnaire is used by pregnan<sup>t</sup> women to self-assess their PA in the current trimester. In PPAQ-PL, the respondents were asked to report the time spent on participation in 32 types of activities grouped under the following categories: *household*/*caregiving* (12 activities), *occupational* (5 activities), *sports*/*exercise* (9 activities = 7 questions + two open questions, allowing the respondent to add any activities not previously listed), *transportation* (3 activities), and *inactivity* (3 activities). The questionnaire measures energy expenditure related to *total activity* and *total activity of light intensity and above* expressed in Metabolic Equivalent of Task (MET) units (MET-h·week−1). Based on the energy expenditure, each of these activities was additionally classified according to intensity: (a) *sedentary activity* [<1.5 METs], (b) *light intensity activity* [1.5–<3.0 METs], (c) *moderate intensity activity* [3.0–6.0 METs], (d) *vigorous-intensity activity* [>6.0 METs]. The MET values were assigned according to the values presented in the questionnaire instruction and the Compendium of Physical Activities [36].

The methodological basis for the assessment of the quality of life (QoL) was provided by the abridged World Health Organization Quality of Life Questionnaire (WHOQoL-Bref), a Polish version provided by Wołowicka and Jaracz [37]. The WHOQoL-Bref questionnaire assesses self-reported QoL and general health of respondents. The WHOQoL-Bref questionnaire consists of 26 questions. The first two questions were analyzed separately. They concerned self-assessed *overall quality of life* and *general health* of the respondents. The remaining 24 questions assessed four domains of the QoL (*physical health domain*: 7 questions, *psychological domain*: 6 questions, *social relationships domain*: 3 questions, and *environmental domain*: 8 questions). The respondents were asked to mark their answers using a five-level rating scale (from 1 to 5 points, in a positive direction: the higher the number of points, the better quality of life). The QoL in the domains was expressed as mean values, calculated according to the key and guidelines provided by the authors [37].

STATISTICA 12.5 software was used for statistical analysis. The significance of the analyzed variables in women in the second and third trimesters of pregnancy was evaluated by means of the Mann-Whitney U-test. Correlations between the variables were analyzed using Spearman's rank correlation test, with correlation coefficients calculated for each pair of variables. The level of statistical significance was set at *p* ≤ 0.05.
