The fatty acid composition in follicles is related to the developmental potential of oocytes up to the blastocyst stage: a single-centre cohort study.

ABSTRACT

BACKGROUND: Advanced maternal age and obesity are associated with impaired female fertility. Moreover, fatty acids (FA) in follicular fluid (FF) play important roles in oocyte maturation and embryo development. However, the effects of body mass index (BMI), age, and FF FA composition on embryo development between days 3 and 5 and blastocyst stage on day 5 are still unclear. METHODS: This study included 138 patients undergoing assisted reproductive technology (ART), which were divided into three BMI groups (18.5-24.9 kg/m2 vs. 25.0-29.9 kg/m2 vs. ≥ 30.0 kg/m2) and three age-related groups (20-30 years vs. 31-34 years vs. ≥ 35 years) which were compared for ART outcomes. Further, observations were divided into quartiles based on either of three parameters related to embryo outcome, i.e. (i) embryos developing between days 3 and 5 (ED3-5) and (ii) expanded blastocysts on day 5 (EB5), both expressed proportionally to the number of oocytes with two pronuclei (2PN), as well as (iii) the embryo utilization rate (EUR). Proportions of FF FA were then compared between Q1 and Q4, representing the quartile with the worst vs. the best embryo outcome, respectively. Finally, regression models were created to assess the relationships between BMI, age, FF total FA (TFA) concentration, relative proportions of specific FA and embryo outcome. RESULTS: Patients of Q1 had higher proportions of FF C205n-3, C226n-3 and total n-3 PUFA than Q4 patients. Furthermore, Q4 patients tended to be younger than Q1 patients. Within the whole cohort, the proportion of C205n-3 negatively correlated with ED3-5/2PN and EUR, while EB5/2PN tended to be negatively correlated with age. Regression models within the overweight and obese group confirmed the negative relation between C205n-3 and ED3-5/2PN, but also indicated additional associations C181n-9 and C204n-6 were positively associated with ED3-5/2PN and EUR, respectively while the proportion of C180 was negatively associated with EUR. CONCLUSION: The proportions of n-3 PUFA, particularly C205n-3 and C226n-3 were reduced in the patients' quartile with the best embryo outcome. This group of patients was also younger. However, the embryo quality parameters of overweight/obese patients were not associated with age but were positively associated with FF C181n-9 and negatively with the proportions of C180 or C205n-3. TRIAL REGISTRATION This study' registration number was B670201627735.