A relative reduction in mid-follicular LH concentrations during GnRH agonist IVF/ICSI cycles leads to lower live birth rates.

The effect of early- and mid-follicular LH concentrations on the ovarian response and pregnancy outcomes was evaluated in women receiving pituitary down-regulation with a GnRH agonist and ovarian stimulation with recombinant FSH (rFSH) during IVF/ICSI treatment. Blood samples were collected prospectively from 701 cycles (560 patients) of assisted reproduction and analysed retrospectively. On the basis of LH concentrations on stimulation day 7/8, the patients were divided into two groups: LH<1.2 IU/l (n=179) and LH>or=1.2 IU/l (n=522). Cycle outcomes were also compared on the basis of a ratio of mid- to early-follicular LH concentrations (<or=0.5, n=210; >0.5, n=491). Patients with low LH concentrations were found to have a significant reduction in the late-follicular estradiol concentrations (P<0.001), the number of oocytes retrieved (P<0.01) and the number of usable embryos (P<0.01), and they required significantly more rFSH (430 IU difference, P<0.01). These differences did not translate into a significant change in live birth rates. Conversely, a ratio of <or=0.5 mid- to early-follicular LH concentrations (a reduction of >or=50%) was associated with a significant reduction in live birth rates per embryo transfer and per cycle started (27.3 versus 19.0%, P<0.05 and 22.2 versus 15.8%, P<0.05, respectively). Low mid-follicular levels of LH have a significant impact on ovarian response but not on live birth rates. A fall in LH level of >or=50% from the early- to mid-follicular phase resulted in a lower live birth rate.