RESEARCHBackground. Recurrent pregnancy loss (RPL) is a source of great distress for couples, and the search continues for an intervention to improve live birth rates in affected women. A daily injection of low-molecular-weight heparin (LMWH) is often prescribed to women with unexplained RPL, although evidence suggesting a benefit is limited. Objective. To compare the efficacy of LMWH with a placebo in terms of live birth rates in women with unexplained RPL. Methods. All pregnant females between 18 and 44 years of age who reported at the unit of obstetrics and gynaecology, Shifa International Hospital, Islamabad, during April 2013 to January 2014, who had a history of ≥2 consecutive first trimester pregnancy losses were enrolled. All participants were randomly allocated to one of two groups. Group A received a daily dose of 40 mg enoxaparin (LMWH) subcutaneously and group B women received a placebo in the form of multivitamin tablets. Efficacy was defined in terms of live births after the age of viability (i.e. 24 weeks' gestation) and was compared in both treatment and control groups. Risk estimation was also performed and relative risk (RR) along with 95% confidence interval (CI) was calculated. Results. The groups were similar in terms of mean age, gestational age and body mass index. Our results showed no statistically significant difference in live birth rates between the two groups, with 78.8% and 73.8% for group A and B, respectively (p=0.0574). A RR of 1.07 (95% CI 0.9 -1.3) was calculated for group A. Conclusion. Subcutaneous enoxaparin in a once daily dose of 40 mg did not improve the chance of live births in nonthrombophilic women with unexplained RPL when compared with the placebo. Recurrent pregnancy loss (RPL) is one of the commonly encountered complications in reproductive medicine, as the aetiology is often unknown and there are few evidence-based diagnostic and treatment strategies available. There are varying definitions of RPL reported that include ≥2 failed clinical pregnancies as documented by ultrasonography or histopathological examination; [1] or 3 consecutive pregnancy losses, which are not required to be intrauterine. [2] The definition of RPL also includes non-visualised pregnancy losses (biochemical pregnancy losses and/or pregnancies of unknown location) as they have the same negative impact on future live birth rate as intrauterine pregnancy losses. [3] The European Society of Human Reproduction and Embryology released a 2014 consensus statement proposing that RPL describes repeated pregnancy loss regardless of anatomic location. They did not recommend the number of losses required for the problem to be defined as recurrent. However, the statement advised researchers and clinicians to clearly describe the type of pregnancy loss, gestational age, number of prior pregnancy losses and relevant details of ultrasound measurements. [4] There is a consensus that healthy women should not undergo extensive evaluation after a single first trimester or early second trimester spontaneous miscar...