Relationship between natural and intrauterine insemination-assisted live births and the degree of sperm autoimmunisation.

STUDY QUESTION: What is the relationship between the degree of sperm autoimmunisation, as assessed by IgG-mixed antiglobulin reaction (MAR) test, and natural and intrauterine insemination (IUI)-assisted live births? SUMMARY ANSWER: Compared with a lower degree of positivity (50-99%), a 100%-positive MAR test was associated with a much lower occurrence of natural live births in infertile couples, who could be successfully treated with IUI, as first-line treatment. WHAT IS KNOWN ALREADY: The World Health Organization (WHO) has recommended screening for antisperm antibodies, through either the IgG-MAR test or an immunobead-binding test, as an integral part of semen analysis, with 50% antibody-coated motile spermatozoa considered to be the clinically relevant threshold. However, the predictive value of the degree of positivity of the MAR test above such a cut-off on the occurrence of natural pregnancies remains largely undetermined. Furthermore, the effectiveness of IUI in cases of strong sperm autoimmunisation is not yet well-established. STUDY DESIGN, SIZE, DURATION: This was a retrospective cohort study on 108 men with a ≥50%-positive MAR test, where the couple had attended a university/hospital andrology/infertility clinic for the management of infertility from March 1994 to September 2017. PARTICIPANTS/MATERIALS, SETTING, METHODS: The IgG-MAR test was carried out as an integral part of semen analysis. The patients were divided into two groups: 100% and 50%-99%-positive MAR test. The post-coital test (PCT) was performed in all the couples, and IUI was offered as the first-line treatment. Laboratory and other clinical data were retrieved from a computerised database. Data on subsequent pregnancies were obtained by contacting patients over the telephone. MAIN RESULTS AND THE ROLE OF CHANGE: A total of 84 men (77.8%) were successfully contacted by telephone, and they agreed to participate. Of these, 44 men belonged to the group with a 100%-positive MAR test, while 40 showed lower MAR test positivity. The couples with a 100%-positive MAR test showed a natural live birth rate per couple (LBR) that was considerably lower than that observed with a lower degree of positivity (4.5% vs. 30.0%; P = 0.00001). Among the clinical variables, a significant difference between the two groups was observed only for the PCT outcome, which was poor in the 100%-positive MAR test group. Better PCT outcomes (categorised as negative, subnormal and good) were positively associated with the occurrence of natural live births (6.3, 21.7 and 46.2%, respectively; P = 0.0005 for trend), for which the sole independent negative predictor was the degree of sperm autoimmunisation. IUI was performed as the first-line treatment in 38 out of 44 couples with a 100%-positive MAR test, yielding 14 live births (36.8%). In couples with lower MAR test positivity, the LBR after IUI (26.9%) was similar to the natural LBR in this group (30.0%). LIMITATIONS, REASONS FOR CAUTION: Given the retrospective nature of the study, we cannot exclude uncontrolled variables that may have affected natural pregnancies during the follow up or a selection bias from the comparison of natural live births with those after IUI. WIDER IMPLICATIONS OF THE FINDINGS: The routine use of the IgG-MAR test in the basic fertility workup is justified as it influences decision making. A 100%-positive IgG-MAR test can represent the sole cause of a couple's infertility, which could be successfully treated with IUI. On the other hand, a lower degree of positivity may only represent a contributing factor to a couple's infertility, and so the decision to treat or wait also depends on the evaluation of conventional prognostic factors including the PCT outcome. STUDY FUNDING, COMPETING INTEREST(S): This study was supported by PRIN 2017, Ministero dell'Università e della Ricerca Scientifica (MIUR), Italy. On behalf of all authors, the corresponding author states that there is no conflict of interest. TRIAL REGISTRATION NUMBER: N/A.