P-749 Maternal and obstetric outcomes following the transfer of embryos warmed with fatty acid supplemented solutions
Authors: Kato K , Amagai A , Onogi S , Ezoe K 
Published: July 2024

Abstract

Study question
Does fatty acid (FA) supplementation into warming solutions influence maternal and obstetric outcomes after single vitrified-warmed cleavage stage embryo transfer (SVCT)?

Summary answer
FA-supplemented warming solutions improve the live birth rate after SVCTs without exerting any adverse effects on maternal and obstetric outcomes.

What is known already
Vitrification procedures decrease the intracellular lipid content and impair developmental competence. Adding fatty acids (FAs) to the warming solution has been shown to recover the lipid content of the cytoplasm and improve developmental competence and clinical pregnancy by stimulating the beta-oxidation pathway in warmed embryos. Recently, the FA-supplemented warming solutions have been commercially released. However, influence of the FA-supplemented supplementation on live birth rate after embryo transfers and perinatal outcomes remains unknown.

Study design, size, duration
The clinical records of 701 treatment cycles in 701 women who underwent SVCTs were retrospectively analysed. Vitrified embryos were warmed using solutions (from April 2022 to June 2022, control group, n = 340) or FA-supplemented solutions (from July 2022 to September 2022, FA group, n = 361). All pregnant women were invited to respond to the questionnaire at 9 weeks of gestation and after delivery. Maternal and obstetric outcomes were obtained from a self-reported questionnaire completed by the patients.

Participants/materials, setting, methods
The embryos in the FA group were warmed with the FA-supplemented solutions (VT526, Kitazato Corporation) while the embryos in the control group were warmed with the non-supplemented solutions (VT506, Kitazato Corporation). SVCTs were performed on day 2 after ovulation in natural cycles. The live birth rate, incidence of pregnancy complications, and neonatal outcomes were compared between the control and FA groups.

Main results and the role of chance
The live birth rate was higher in the FA group than in the control group (P = 0.0399). The miscarriage rates were comparable between the groups. Multivariate logistic regression analysis also demonstrated a higher probability of live births in the FA group than in the control group (adjusted odds ratio, 1.46; P = 0.0404). Patients were stratified by median maternal age for further analysis (37 years). This subgroup analysis showed that the live birth rate was significantly higher in the FA group than in the control group in women younger than 37 years of age. However, the live birth rate was comparable between the two groups for women aged 37 years or older. The incidence and types of pregnancy complications were comparable between the control and FA groups. Furthermore, caesarean section rates were similar between the groups. The average gestational age and incidence of preterm delivery were comparable between the groups. Birth length and weight, incidence of low birth weight, incidence of small for gestational age and large for gestational age, and infant sex were comparable between the groups. The incidence of birth defects was similar between the groups. Multivariate logistic regression analysis revealed a similar trend.

Limitations, reasons for caution
The single-centre retrospective study limits the strength of the study, necessitating further multicentre studies to ascertain the generalizability of these findings to other clinics with different protocols and/or patient demographics. Furthermore, the number of perinatal cycles was low.

Wider implications of the findings
The FA-supplemented warming solutions improved the live birth rates after SVCTs, particularly in young patients. Furthermore, the incidence of pregnancy complications and infant health was not affected by the FA-supplemented solutions. Therefore, FA-supplemented solutions can be considered safe and effective at improving clinical outcomes and reducing the patient burden.

Trial registration number
not applicable