A randomized, controlled clinical study of low-molecular-weight heparin improving pregnancy outcomes in PCOS women undergoing IVF: study protocol.

BACKGROUND: Polycystic ovary syndrome (PCOS), an incidence of 10-15% in women of reproductive age, shows sex hormone disorders, luteal insufficiency, and the tendency of placental villus space thrombus. The incidence of early pregnancy loss in women with PCOS is three to eight times higher than that in non-PCOS women. PCOS women were reported in a pre-thrombotic state, which was manifested by accelerated thrombin production, increased PAI-1 activity, and fibrinogen. Other research also found an over-activated state of women with PCOS in immune system. Therefore, changing the prethrombotic state of PCOS through anticoagulation may be a new way to improve the adverse pregnancy outcome of PCOS. Low-molecular-weight heparin (LMWH) is the most common used anticoagulant drug in pregnancy, and it also was proposed for the prevention of recurrent abortion, although the application of LMWH in PCOS population during early pregnancy has not been reported. The objective of this study is to investigate the effect of LMWH on pregnancy outcomes after invitro fertilization-frozen embryo transfer (IVF-FET) in patients with polycystic ovary syndrome.

METHODS: A total of 356 PCOS women aged between 20 and 38 years which prepared for IVF followed with FET will be enrolled in the study. The patients, from four different hospitals stratified by age and body mass index (BMI), will be randomly divided into the study group who will be treated with LMWH started on the day of progesterone transformation (hormone therapy) during FET cycle and the control group without additional medicine. Serum or urine hCG test will be given 14 days after embryo transfer to confirm biochemical pregnancy. If pregnancy is positive, LMWH+ hormone therapy/hormone therapy will be continued for another 2 weeks. Transvaginal ultrasonography will be performed 14 days later to confirm intrauterine pregnancy. The primary outcome is the ongoing pregnancy, which is defined as intrauterine live fetus with ultrasound after 12 weeks of gestation.

DISCUSSION: This is the first study protocol to investigate the efficacy of LMWH as an adjuvant drug for IVF-FET outcomes in PCOS women, by comparing differences in ongoing pregnancy rate, clinical pregnancy rate, live birth rate, and early pregnancy loss rate between LMWH group and the control group.

TRIAL REGISTRATION: ClinicalTrials.gov ChiCTR2000036527. Registered on August 24, 2020.