Aims to highlight the changes occurred in the evolution of the fertility phenomenon in Romania, focusing on developments in the general fertility rate, total fertility rate, number of live births, and on the construction of specific indicators to reveal the source of demographic change. Several theories on the factors that may cause fertility decline it were outlined, underlining the presence of these factors during fertility dynamics in our country. After 1990, population decline may be explained by a close inter-relationship between economic theories (worsening economic conditions lead to decreased fertility) and the second demographic transition (postponement of births, fertility change model).