The aim of this study was to improve knowledge regarding pregnant couples by assessing changes in their sexual behavior, the reasons for the frequency and forms of intercourse, and the self-sexuality of partners in each trimester of pregnancy. As a result, 100 couples were qualified to take part in the final study, with 100 men and 100 women examined at intervals equivalent to the trimesters of pregnancy. These women (n = 100) and men (n = 100) were partners. Each of the studied couples was assessed in the trimesters of pregnancy. A prospective examination was conducted based on the observation of the same people, which were heterosexual couples, throughout pregnancy. The data used in the study was obtained using Davies’ Sexual Satisfaction Scale (DSSS), as well as an original survey on the sexuality of people during pregnancy (SARSS). The survey allowed us to obtain sociodemographic (metrics) information along with information regarding the sexual activity, satisfaction, and sexual attraction of the partners. All questionnaire questions were answered in paper form. There was a statistically significant drop in sexual intercourse from the first trimester in the second and third trimesters. The frequency of masturbation increased in men and decreased in women. The most common cause of sexual abstinence during the pregnancy was cited as fear for the fetus by all genders. A statistical analysis indicated that the average overall scores of the DSSS for the examined women in the first trimester of pregnancy were statistically significantly higher than in the two subsequent trimesters (p < 0.05). Sexual satisfaction, measured through both DSSS and SARSS, was also strongly correlated with the level of satisfaction in the assessment of the partner relationship and with the sense of one’s own attractiveness (p < 0.05). Changes in sexual behavior and sexual problems are often exposed or worsened during a first pregnancy and can have negative impacts on a person and the future of relationships. Medical staff should be trained in the assessment of sexual difficulties in people during pregnancy, in order to conduct reliable education and increase the awareness of couples regarding sexual and reproductive health.