Ultrasound examination surveys carried out during puerperium or pregnancy have demonstrated the presence of biliary sludge and gallstone with a percentage of the examined women varying from 30% to 40%. Our aim was to evaluate the incidence of biliary sludge and gallstones during pregnancy and the natural history of this pathology after delivery in our rural population. Fifty six pregnant women entered the study. The pregnant women were subjected to ultrasonography during the 12th-14th and the 34th-36th week of amenorrhea, and two weeks after delivery. Women with biliary sludge or gallstones were subjected to a further ultrasound examination 12 months after delivery. At the first ultrasonography, women were questioned about menarche, menstruation (rhythm, intensity and period), previous pregnancies, number of deliveries, use of oral contraceptives and possible abdominal symptoms connected with the pathology of gallbladder. Besides, in order to form the body mass index (BMI) [weight (kg)/height (m)2], weight and height were obtained from each subject. Before the second ultrasonography, women were questioned about abdominal symptoms connected with the pathology of gallbladder. It was assessed the weight in order to calculate the ponderal increase during pregnancy. Biliary sludge or gallstones were found at ultrasound examination in: 5 out of 56 women in the first trimester (one woman with gallstones, 4 with sludge); 9 out of 49 women examined in the third trimester (2 women with gallstones, 7 with sludge); 2 out of 46 women examined were still affected by gallstones two weeks after delivery.(ABSTRACT TRUNCATED AT 250 WORDS)