It is well documented that small-for-gestational age (SGA) infants are at an increased risk of perinatal mortality and morbidity. In order to identify the major modifiable risk factors of SGA birth, a case-control study was launched in the area of Lódź voivodeship, Poland. The project was focused on the evaluation of the role of perinatal health services and avoidance of exposure to tobacco smoke in the prevention of SGA births. The study population consisted of mothers of 153 SGA infants (cases) and 93 mothers of control infants. SGA infants were identified as infants with body weight below 10th percentile for gestational age, using Ballarda scale. The controls were non-SGA infants delivered after 37 week of gestation. The infants from both groups were delivered in 26 maternity wards in the Lódź voivodeship within the period of June 1-November 1, 2003. One month after delivery, each mother of SGA and control infants was visited by an interviewer who collected information about her profile of use of perinatal health care and on active and passive exposure to tobacco smoke in pregnancy. Odds ratios and 95% confidence units (CU) were calculated using EpiInfo software developed by CDC, Atlanta, Georgia, US. Late booking for perinatal care (after 12 week of gestation) and less than 5 visits during pregnancy was found to be related to an increased risk of SGA, however, the OR values included unity. About 1/3 of mothers of SGA infants and "of the controls were served mainly by the private health sector. The use of private care was related to a lower risk of SGA: OR= 0.55 95% CI (0.31-0.96). This protective pattern was observed in the population of women aged 19-25 living in rural areas years and with only primary education. The preconception visits to obstetricians and contacts with health educators during pregnancy were also found to have some protective effect, however, the ORs were not statistically significant. The adverse effect of smoking during pregnancy was clearly confirmed in the study population, OR= 2.69 95%CI (1.37-5.33), while the role of passive smoking was difficult to assess due to the small number of nonsmoking women exposed to ETS. There are some indications that the poor use of perinatal health services may account for the elevated risk of SGA births in the Lódź voivodeship. The use of the private health sector is growing and seems to be related to a lower risk of SGA births. More effective tools to prevent maternal smoking have to be developed and implemented in routine perinatal care.