Association between luteinizing hormone level decrease on the triggering day and pregnancy outcome for in vitro fertilization/intracytoplasmic sperm injection patients following gonadotropin-releasing hormone antagonist protocol: a retrospective cohort study

Abstract

Objective: Optimal luteinizing hormone (LH) levels for in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) patients following the gonadotropin-releasing hormone (GnRH) antagonist protocol remain controversial. This study aimed to estimate the association between serum LH levels on the triggering day (LHLOT) and clinical pregnancy outcomes in IVF/ICSI patients following the GnRH antagonist protocol. Methods: We enrolled 4743 IVF/ICSI cycles using flexible or fixed GnRH antagonist protocols between January 2017 and June 2021. The patients were stratified into four groups according to the LHLOT quartiles (Q1–Q4). Each group was further divided into two subgroups according to the median basal LH/LHLOT. The main outcomes were clinical pregnancy, birth, and miscarriage rates. Secondary outcomes were oocyte yield, number of MII, fertilized oocytes (2PN), and high-quality embryos. Results: Serum LHLOT levels were negatively correlated with oocyte yield and the numbers of MII, 2PN, and high-quality embryos. Reproductive outcomes were compared among the different quartiles and subgroups. The absolute difference in the clinical pregnancy rates between the Q4 and Q1 groups was 6.4% (47.2% vs. 40.8%, P <0.05). Clinical pregnancy rates between the subgroups with basal LH/LHLOT >3.04 and ≤3.04 were 32.7% and 48.6% (P <0.01), respectively, in Q1. Within Q3, the clinical pregnancy rates between the subgroups with basal LH/LHLOT >2.14 and ≤2.14 were 50.2% and 41.9%, respectively (P <0.05). The greater the decrease in LH levels, the lower the oocyte maturation rate across all quartiles. Conclusions: According to the LHLOT quartiles, the Q1 of serum LHLOT <1.43 IU/L may result in a higher number of oocytes but reduced oocyte maturation and lower clinical pregnancy rates. A decrease in LH levels by approximately 2.14 to 3.04 times compared to basal LH levels may lead to higher clinical pregnancy rates in IVF/ICSI patients following the GnRH antagonist protocol.