NVPLs is a recognized category in patients with RPL. It is defined as spontaneous pregnancy loss based on decreasing serum or urinary beta-human chorionic gonadotrophin (hCG) in absence of ultrasonographic or histopathologic evidence of pregnancy. The objective of this study is to evaluate the prevalence of couples who experienced only NVPLs in RPL cohort attending tertiary centre and their causes compared to couples who experienced only visualized pregnancy losses (VPLs).


Retrospective chart review

Materials and Methods

This study was approved by University of British Columbia (UBC) ethics board (H13-03306). A total of 1064 couples with RPL referred to BC women’s RPL clinic (Vancouver, Canada) from January 2011 to March 2016, were evaluated according to American Society of reproductive medicine (ASRM) recommendations which include anatomical factors by hysterosalpingography or hysteroscopy, endocrine factors by measurement of serum thyroid stimulating hormone (TSH), testing for antiphospholipid antibodies (aPLs) and parental karyotyping. Their full reproductive histories were reviewed from their medical charts. The primary outcome is the prevalence of NVPLs. It includes biochemical pregnancy losses (BPLs) and failed pregnancy of unknown location (PUL). The secondary outcome is the contributing factors association; uterine cavity evaluation, thyroid dysfunction, seropositivity for (aPLs), and parental karyotyping and the ongoing pregnancy rate beyond 12 weeks in both only VPLs and only NVPLs groups. Analysis was done using student t- test, Fisher’s exact and chi- squared test when appropriate, significance was detected when p<0.05.


The overall age (mean ± SD) of the study group was 33±5.36 years. The age and body mass index of the NVPLs is comparable to VPLs category. 151 (14. 19 %) couples were found to have only NVPLs while 272 (25.56%) couples were only VPLs. The remaining couples 641 (61.28 %) have mixture of both. In couples with NVPLs group, the total number of losses achieved was 443; 347 (78.33%) were biochemical losses and 96 (21.67%) were PUL. Uterine abnormalities were found significantly more often in the VPLs compared to NVPLs [(26% vs. 12%); (OR 0.4, 95% CI 0.20 to 0.79)]. There is no significant difference in other systems evaluations between both groups. Patients with NVPLs are more likely to have pregnancy continuation beyond 12 weeks in this cohort compared to VPLS patients (P <0.05).


Pure NVPLs is frequently encountered in a tertiary referral RPL program. This specific group share the same causes with patients with VPLs. However, they are less likely to be associated with uterine anatomic defects. A larger study is suggested to further characterize NVPLs.


  • 1-Kolte AM,van Oppenraaij RH,Quenby S,Farquharson RG,Stephenson M, Goddijn M,Christiansen OB; ESHRE special interest Group Early pregnancy. Non-visualized pregnancy losses are prognostically important for unexplained recurrent miscarriage. Human Reprod 2014; 29:931-937.