Despite the extensive research on the consequences of migration, little is known about the effects of seasonal migration on fertility, contraception and sexually transmitted diseases in the countries of former Soviet Union, that have undergone vast demographic changes in the last two decades. Using cross-sectional data from two surveys conducted in Armenia in 2005 and 2007, this dissertation is exploring the effects of seasonal migration on reproductive behavior and outcomes, as well as sexual health among women left-behind. The dissertation is constructed of three independent studies that combined draw the broad picture of the consequences of seasonal migration in this part of the world. The first study, "Seasonal migration and fertility in low-fertility areas of origin" looks at the effect of seasonal migration on yearly pregnancy rates, lifetime fertility, and fertility preferences among women and their husbands. The models are fitted using discrete-time logistic regression, and random-intercept logistic regression for negative binomial and binary outcomes, correspondingly. The findings show that seasonal migration in low-fertility settings does not further disrupt fertility levels in a short-, or long-run, contradicting to the findings from high-fertility settings. However, the study provides some evidence that seasonal migration is associated with increased fertility preferences among migrant men. The second study, "Seasonal migration and contraception among women left-behind", examines the associations between migration and modern contraceptive use, by looking at current contraceptive use and the history of abortions. A series of random-intercept logistic regression models reveal that women with migrant partners are significantly less likely to use modern contraceptives, than women married to non-migrants. They also have higher rates of abortions; however this effect is moderated by the socioeconomic status of the household. The third study, "Seasonal migration and risks of sexually transmitted diseases (STDs) among women left-behind", looks at the effects of seasonal migration on the diagnosed STDs in the last three years, and self reported STD-like symptoms in the last twelve months. The results of random-intercept logistic regression for negative binomial and binary outcomes provide strong evidence of increased STD risks among migrants' wives; however, this effect is also moderated by the household income.