The authors point out the problems that are raised when a patient with cystic fibrosis becomes pregnant. Pregnancy in a patient with cystic fibrosis is rare but these patients do not seem to have diminished fertility. So it is likely that in the future this combination will increase in frequency. The genetic risk is raised. Heterozygotic subjects are about 3 to 5% of the population and there is a risk of 1 in 4 that heterozygotic parents who already have one child with cystic fibrosis will have a second. The BM test and the sweat test are used to screen for the disease at birth. The pregnancy does not always progress well. The level of prematurity is more than 26% and perinatal mortality is 11%. Furthermore, the birthweight of these children is at the lower limits of normal. Finally, the pregnancy makes the mother's state worse with an increase in her lung signs and change in her respiratory function. On the other hand, diabetes seems to be easily controlled. In conclusion, pregnancy seems to be detrimental for these patients.