**2.1. Summary points**

58 Enhancing Success of Assisted Reproduction

**10** 

**LH (IU/L)** 

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**1 0** 

green) to maximize ART outcomes.

LH Threshold

LH Window

LH Ceiling

implantation rates, and lower live birth rates (57, 58).

There is evidence to suggest that suppressed LH levels in women during ART stimulation can have negative effects (Figure 4). Depending on the study, adverse outcomes have been demonstrated with LH below 0.5-1.2 IU/L. LH levels < 1.2 IU/L have been reported to be associated with decreased serum estradiol, poor follicular development, decreased oocyte yield, decreased high quality embryos, and lower pregnancy rates (14, 15). Below LH levels of 1IU/L, other researchers demonstrated slower follicular growth and decreased estradiol (56). Finally, LH levels < 0.5 IU/L have been associated with increased pregnancy loss, lower

**Figure 4.** Demonstrates the concept of an LH window. Low LH levels have been associated with decreased poor pregnancy outcomes with levels below 0.5-1.2 IU/L, demonstrating a threshold below which low LH causes poor outcomes. High LH levels have also been associated with poor pregnancy outcomes with levels over 6.8-10 IU/L. This gives rise to the concept of a therapeutic LH window (in

It has also been demonstrated that elevated LH levels are associated with negative ART cycle outcomes. Decreased pregnancy rates and increased spontaneous abortion were reported with LH levels above 10 IU/L (59). Increased follicular arrest, decreased fertilization, higher recurrent pregnancy loss, and lower implantation rates have all been reported in patients with higher LH levels that controls, although ceiling values were not established in these studies (56, 60-63). This evidence that too much or too little LH activity can have negative outcomes has led to the concept of an LH window (4, 61, 64). In reality,

Westergaard *et al.* 2000- Increased pregnancy loss with LH <0.5 Propst *et al.* 2011- Decreased implantation and live birth with LH <0.5 Fleming *et al.* 1996- Decreased E2 and slower follicular growth LH <1 Odea *et al.*,2008 Decreased E2, no follicles, no pregnancies with LH <1.2

Regan *et al.* 1990- Lower PR and increased SAB with LH >10

Loumaye *et al.* 2003- Follicular arrest with LH of 6.8

Lahound *et al.* 2006- Decreased E2, decreased oocytes, fewer good embryos with LH <1.2

Watson *et al.*1993- recurrent pregnancy loss group had higher endogenous LH levels of 4.8 Kolibianakis *et al.* 2003- Lower implantation rates and higher LH levels in fixed antagonist group

Stranger *et al.* 1985- Decreased fertilization rate when LH levels >1 SD above the mean

