Are there predictive characteristics for pregnancy in couples treated for unexplained infertility? Analysis from the fast track and standard treatment (FASTT) trial

Abstract

OBJECTIVE: To compare characteristics of couples with unexplained infertility who became pregnant with clomiphene (CC)/IUI, FSH/IUI, or IVF to those who did not become pregnant. DESIGN: Data are from a randomized controlled clinical trial in which couples (n=503) were randomized to receive either conventional treatment (n=247) with 3 cycles of CC/IUI, 3 cycles of FSH/IUI, and up to 6 cycles of IVF or an accelerated treatment regimen (n=256) that omitted the 3 cycles of FSH/IUI. Assignment was stratified by age (<35 v ≥ 35), laparoscopy within one year (yes/no), and study site. MATERIALS AND METHODS: Patients had unexplained infertility without prior treatment. The outcome measure was sustained pregnancy. The analysis used a discrete time-to-event model (with cycle as the time unit) to assess the association of patient factors with pregnancy achieved by a specific treatment. The models for CC/IUI and IVF cycles were stratified by randomization arm. Factors analyzed were age at randomization, BMI, prior oral contraceptive use, smoking status, time attempting pregnancy, parity, gravidity, cycle day 3 FSH, history of laparoscopy, male smoking status and age. RESULTS: 475 couples initiated CC/IUI cycles. 98 (21%) became pregnant in the first 3 cycles (1266 cycles):42 in cycle 1; 29 in cycle 2; and 27 in cycle 3. 169 couples initiated FSH/IUI cycles for which 43 (25%) became pregnant (439 cycles):18 in cycle 1; 14 in cycle 2; and 11 in cycle 3. 283 couples initiated IVF cycles for which 191 (67%) became pregnant (622 cycles): 92 in cycle 1; 52 in cycle 2; 31 in cycle 3; 12 in cycle 4; and 4 in cycle 5. There were no variables associated with pregnancy for each of the treatment steps. CONCLUSIONS: No characteristics were identified in treatment naïve couples with unexplained infertility that predicted increased likelihood of pregnancy during either CC/IUI, FSH/IUI, or IVF treatments. There do not appear to be couples who would benefit from omitting CC/IUI prior to moving directly to IVF.