Young, fertile women (and men) are also smoking in increasing numbers, and they do not stop their habit during pregnancy, breastfeeding, or while preparing for pregnancy. Aims: The aim of this work is to investigate the exact effects of smoking on the health of pregnant women and the fetus, and how it increases the risk of preterm birth and other developmental problems. Methods: The research esed a questionnaire-based survey. The empirical research involved 87 women who smoked before and/ or during their pregnancy. Results: Most started smoking between the ages of 14 and 16 years (49 persons, 57%). The highest proportion was among those who smoked 5-10 cigarettes per day (274%). 96.3% of respondents did not seek help to stop smoking. The reasons for this were fear of being judged for smoking during pregnancy. The proportion of women who gave birth prematurely is high (471%). Prenatal care professionals do not adequately inform pregnant women and do not adequately help them to quit smoking. Conclusions: Smoking during pregnancy can have serious consequences for the development of the fetus and the health of the child, especially with regard to preterm birth and its complications. The results of the research indicate that more attention should be paid to maternal smoking cessation during pregnancy and to primary prevention.  Kulcsszavak: smoking, pregnancy, prematurity, primary prevention