A discrepancy exists between the interest in modern methods of natural family planning (NFP) and their actual use in developed countries. To explore reasons for this discrepancy, we analyzed data from a questionnaire administered to postpartum women in Berlin (n = 223) and Cracow (n = 233). Knowledge of NFP, past use of NFP and expected effects of abstinence on the partnership were independently associated with interest in using NFP, but not the choice to do so among those interested. Desire for future pregnancies, importance of religious belief and location in Cracow were independently associated with the choice to use NFP among those interested. Perceived accuracy of observation to identify the fertile time and acceptance of own body were independently associated with both interest in and choice to use NFP. Frequency of intercourse had no effect on interest. These results suggest that increased access and cultural support would likely lead to a higher prevalence of NFP use in developed countries.