P-419 Relevance of intravenous immunoglobulins in patients with unexplained recurrent pregnancy loss that occurred at the same gestational weeks every time
Authors: Usui K , Matsubayashi H , Saito S , Ishibashi Y , Karino A , Ohara Y , Doshida M , Takeuchi T , Ishikawa T 
Published: July 2024

Abstract

Study question
Are intravenous immunoglobulins (IVIG) effective for the selected patients who experienced unexplained recurrent pregnancy loss (RPL) that occurred at the same gestational weeks every time?

Summary answer
IVIG before and after the gestational week-limit (GWL), where miscarriage occurred at the same gestational weeks every time, may improve pregnancy outcomes in RPL patients.

What is known already
There is no established treatment for patients with unexplained RPL. Some investigators have indicated that IVIG may exhibit therapeutic efficacy in women with unexplained RPL. Since it has been reported that live birth rate significantly increased in women with four or more RPL of unexplained etiology, who received a high dose IVIG at 4-5 weeks of gestation in 2022, ESHRE Guideline Group on RPL (2022) has changed the recommendation to the following: the use of repeated and high doses of IVIG very early in pregnancy may improve live birth rate in women with four or more unexplained RPL.

Study design, size, duration
We performed a retrospective study between September 2013 to March 2023 in two fertility centers. We included 164 patients in the study who experienced 2 or more miscarriages between 5 and 21 weeks of gestation that occurred at the same gestational weeks every time, who had all negative results for our routine RPL work up and still unsuccessful result after treating these conditions, and whose products of conceptus (POC) revealed at least one normal karyotype.

Participants/materials, setting, methods
IVIG (Venoglobulin IH 5%, Japan Blood Products Organization, 0.4g/kg) injection was performed twice before and after 1 week of GWL. We divided 164 patients into IVIG group and non-IVIG group by their own choice. The primary outcome was live birth rate, and the secondary outcome was modified live birth rate excluding pregnancies with abnormal fetal karyotype, maternal and neonatal complications. All participants provided written informed consent, and Institutional Review Board approval was obtained.

Main results and the role of chance
IVIG group (n = 116) and non-IVIG group (n = 48) showed no significant differences in the background of patients on BMI (20.3±3.7 and 21.1±2.8), age (37.4±4.2 and 36.7±3.2) and Childbirth history (20.7% and 23.0%), respectively (average±SD), except for the history of past miscarriages. Average numbers of previous miscarriages on IVIG group and non-IVIG group were 3.2±1.3 and 2.5±0.8 (p &lt; 0.001), respectively. After multivariate analysis for BMI, age, Childbirth history and previous miscarriages, live birth rate of IVIG group (70.7%, 82/116) was significantly higher than that of non-IVIG group (60.4%, 29/48; Odds ratio 3.40, 95% CI: 1.49-7.74, p = 0.003). Similarly, modified live birth rate of IVIG group (73.9%, 82/111) was significantly higher than that of non-IVIG group (63.0%, 29/46; Odds ratio 3.40, 95% CI: 1.49-7.74, p = 0.003). Treatment outcomes when IVIG was used for each number of previous miscarriages, the modified birth rate was 88.3% for two times miscarriages, 77.0% for three times, and 57.1% for four or more miscarriages. Maternal complications were observed in 2 cases in IVIG group (chest tightness, obstetric critical bleeding). There were no significant differences in the birth weight, gestational weeks, preterm birth, or fetal growth restriction of newborns between two groups.

Limitations, reasons for caution
Since retrospective nature and we did not perform POC tests for all patients whose pregnancies had ended in miscarriage, we could not assert the effectiveness of IVIG. We need to conduct randomized controlled trial using placebo group to demonstrate the IVIG efficacy before and after the GWL using euploid blastocysts.

Wider implications of the findings
IVIG before and after the GWL adjusted for each patient may improve pregnancy outcomes in RPL patients. Although IVIG is expensive, the current method requires only two IVIG injections, that may be acceptable for much more patients who want to avoid miscarriages and who didn’t use IVIG for economic reasons.

Trial registration number
NA