Pregnancy requires the cells of the woman’s body to ensure increased ribosomal biogenesis in order to enhance the protein synthesis intensity. The number of ribosomes depends on the copy number of ribosomal genes (rDNA) in the genome. The study aimed to test the hypothesis about the association of the rDNA copy number in the woman’s genome with the course of normal and complicated pregnancy. The sample of 488 pregnant women (25–39 weeks) included the following groups: 1) normal pregnancy (control); 2) impaired uteroplacental blood flow and fetoplacental insufficiency; 3) congenital malformations; 4) isthmic-cervical insufficiency; 5) early placental maturation; 6) dichorionic diamniotic twins; 7) polyhydramnios; 8) macrosomia. The rDNA copy number was determined by the quantitative hybridization method in the DNA extracted from peripheral leukocytes.  The rDNA copy number varied between 226 and 800 (n = 488). DNA samples with the rDNA copy number below 290 were lacking in groups 3–8. Groups 5–8 included no samples with the rDNA copy number exceeding 520; these in total differed from group 1 by low rDNA copy number values (the average values were 360–381 for groups 3–8 and 452 for group 1; p < 10–7). The rDNA copy number range of 290–520 in the woman’s genome (the adaptive norm typical for long-lived individuals) is optimal in terms of successful completion of pregnancy in the presence of pregnancy complications. The low rDNA copy number (200–290) in the genome is associated with the failure to complete embryogenesis when there are some fetal abnormalities/ features. A high rDNA content (over 600 copies) indicates the presence of genetic variants in the woman's genome that can interfere with the complicated pregnancy course. Determining the rDNA copy number in the genome of married couples may be useful for planning and predicting the course of pregnancy.