OBJECTIVES The demand for genetic amniocentesis in case of young pregnant women has significantly increased due to various new indications. Moreover, nowadays a growing number of women aged > or =35, who required genetic amniocentesis, get pregnant The aim of the following study has been to compare the course of the pregnancy, the delivery and the condition of the newborn in two groups of patients: 18-34 years old and > or =35 years old. MATERIAL AND METHODS 783 women underwent the procedure of amniocentesis at the Department of Obstetrics of Medical University of Gdansk in 1996-2003. A group of 540 women, who answered the questionnaire about the course of the pregnancy and the delivery after the procedure, has been isolated. RESULTS Fetal loss occurred in 2 cases (1.6%) in the group of the younger women and in 8 cases (0.8%) in the group of > or =35 year-olds (p=0.84). There was no statistically significant difference between younger and older patients when comparing complications after the procedure in the first three weeks following amniocentesis: spotting, bleeding, leakage of amniotic fluid. Frequency of late complications such as gestational diabetes mellitus, pregnancy induced hypertension and urinary tract infections were comparable in both age groups women. Cesarean section has been more frequently performed in case of the older women than in the group of younger patients, with statistical difference p=0.003. In most cases (33.9%) it has been an elective cesarean section, performed due to advanced maternal age rather than any obstetric cause. Frequency of pneumonia and the number of respiratory infections in the newborns have been comparable in both groups. CONCLUSIONS Prenatal invasive diagnosis has no influence on frequency of complications during pregnancy and delivery in the group of women less than 35 years old and more than 35 years old.