STUDY QUESTIONIs there a difference in fertility between heterosexual women and lesbians undergoing sperm donation?SUMMARY ANSWERWomen undergoing treatment with donated sperm are equally fertile regardless of sexual orientation.WHAT IS KNOWN ALREADYLesbians have an increased prevalence of smoking, obesity, sexually transmitted diseases and, possibly, polycystic ovary syndrome, all factors known to affect fertility. Previous studies on sperm donation inseminations (D-IUI) show conflicting results regarding pregnancy outcome.STUDY DESIGN, SIZE, DURATIONThis is a national study of 171 lesbians and 124 heterosexual women undergoing sperm donation both as D-IUI (lesbian n = 438, heterosexual n = 298) and as embryo transfers (ET) after IVF with donated sperm (lesbians n = 225, heterosexuals n = 230) during 2005–2010.PARTICIPANTS/MATERIALS, SETTING, METHODSAll clinics in Sweden offering sperm donation recruited patients. Differences in patients' medical history, treatment results and number of treatments to live birth were analyzed using independent samples t-test, Pearson's χ2 test or Fisher's exact probability test.MAIN RESULTS AND THE ROLE OF CHANCE71.8% of heterosexuals and 69.0% of lesbians had a child after treatment. The mean number of treatments was 4.2 for heterosexual women and 3.9 for lesbians. The total live birth rate, regardless of treatment type, was 19.7% for heterosexuals and 19.5% for lesbians. For D-IUI, the live birth rate was 12.8% for heterosexuals and 16.0% for lesbians and the live birth rate for all IVF embryo transfers (fresh and thawed cycles) was 28.7% for heterosexuals and 26.2% for lesbians. There were no differences in live birth rate between the groups for each of the different types of insemination stimulations (natural cycle; clomiphene citrate; FSH; clomiphene citrate and FSH combined). Nor was there a difference in live birth rate between the groups for either fresh or thawed embryo transfer. There was no difference between the proportions of women in either group or the number of treatments needed to achieve a live birth. Heterosexuals had a higher prevalence of smokers (9.2%), uterine polyps (7.2%) or previous children (11.3%) than lesbians (smokers 2.8%, P = 0.03; polyps 1.8%, P = 0.03; child 2.5%, P = 0.003).LIMITATIONS, REASONS FOR CAUTIONThis study is limited to women living in stable relationships undergoing treatment with donated sperm in a clinical setting and may not apply to single women or those undergoing home inseminations.WIDER IMPLICATIONS OF THE FINDINGSThese results may influence healthcare policy decisions as well as increase the quality of clinical care and medical knowledge of healthcare professionals. The data also have important implications for individuals regarding screening, infertility diagnostic procedures and treatment types offered to heterosexuals and lesbians seeking pregnancy through sperm donation.STUDY FUNDING/COMPETING INTEREST(S)Funding was granted by the Stiftelsen Familjeplaneringsfonden i Uppsala; the Swedish Research Council for Health, Working...