To discuss the effect of human chorionic gonadotropin (HCG) injection day serum luteinizing hormone (LH) levels on pregnancy outcome in women undergoing in vitro fertilization-embrgo transfer (IVF-ET) with long protocols.

A retrospective study including 1 461 cases was performed in reproductive center affiliated to Shandong University from January 2016 to December 2017. Serum LH levels were measured on the day of HCG administration. Two groups were divided according to the ROC curve between serum LH levels and pregnancy outcome, the LH≤1.58 IU/L in group A and LH>1.58 IU/L in group B. The Logistic regression was used to analyze the relationship between the total dose, duration of gonadotropin (Gn) and the clinical pregnancy rate.

The duration of Gn in group A was (11.28±2.46)d, which was longer than that in the group B[(9.92±2.09)d], and the difference was statistically significant (t=8.99, P<0.01). The total dose of Gn in group A was (2 322.13±1 054.77)IU, which was higher than that in the group B[(1 789.85±692.51)IU], and the difference was statistically significant (t=8.60, P<0.01). The clinical pregnancy rate of group A (61.8%, 201/325) was lower than that in group B(69.7%, 792/1 136), and the difference was statistically significant (χ²=7.21, P<0.01). The early abortion rate of group A (11.9%, 24/201) was lower than that in group B(6.7%, 53/792), and the difference was statistically significant (χ²=5.37, P<0.05). According to the Logistic regression, neither the duration of Gn (B=-0.005, wald χ²=0.052, OR=0.995, P>0.05), nor the total dose of Gn(B=0.000, wald χ²=0.000, OR=1.000, P>0.05) was the independent risk factors for clinical pregnancy rate.

During long protocol, for the patients with the LH levels less than 1.58 IU/l on the day of HCG administration, the duration of Gn extended, the total dose increase, and it will lead to the lower pregnancy and higher early abortion rate. The total dose, and duration of Gn are uncorrelated with the clinical pregnancy rate.