One of the major social and public health problems in the world is adolescent pregnancy. Adolescent pregnancy is strongly associated to less favorable results for both the mother and the newborn. We conducted this research to ascertain the impact of teenage age on neonatal outcomes and also observed the lifestyles of pregnant teenage girls. We conducted a study of 2434 mothers aged ≤19 years (n = 294) or 20-34 years (n = 2140) who gave birth in 2019-2020 at the Department of Gynaecology and Obstetrics of Louis Pasteur University Hospital in Košice. The data on mothers and newborn infants have been reported from the reports on mothers at childbirth. Women between the ages of 20 and 34 served as the reference group. The teenage mothers were more likely to become pregnant if they were unmarried (OR = 14.2; 95% CI = 9.3-21.6; p < 0.001) and had a basic education or lack of education (OR = 16.8; 95% CI = 11.5-24.6; p < 0.001). Additionally, they were more likely to smoke when pregnant (OR = 5.0; 95% CI = 3.8-6.6; p < 0.001). Low birth weight was more common in newborns born to adolescent mothers than in those born to adult mothers (p < 0.001). Our findings showed that infants of teenage mothers often had lower birth weights (-332.6 g, p < 0.001). Adolescent mothers were associated with lower Apgar scores at the first minute (p = 0.003). As compared with the control group, pregnant teenage girls had a greater prevalence of preterm deliveries in our research (p = 0.004). This study finds significant age-related disparities in neonatal outcomes between mothers. These results might be used to identify vulnerable groups who need special assistance and actions to reduce the probability of negative outcomes for such groups.