The Influence of Follicular Fluid Metals on Assisted Reproduction Outcome

Abstract

Infertility has become more common, with an increased exposure to toxic compounds including heavy metals (HM). Follicular fluid (FF) surrounds the developing oocyte in the ovary and can be analysed to assess metal content. The levels of twenty-two metals were measured in the FF of ninety-three females in a reproduction unit, and their influence on assisted reproduction technique (ART), were examined. The metals were determined by optical emission spectrophotometry. Low values of copper, zinc, aluminium, and calcium favour polycystic ovary syndrome. The relationships between the number of oocytes and metals: iron (rs=0.303; p=0.003) and calcium (rs=−0.276; p=0.007) are significant, as well as between the number of mature oocytes with iron (rs=0.319; p=0.002), calcium (rs=−0.307; p=0.003) and sodium (rs=−0.215; p=0.039) and are near to significance in the case of aluminium (rs=−0.198; p=0.057). In the group with a fertilisation rate ≤ 75%, 36% of the women presented calcium >176.62 mg/kg compared to the group with a fertilisation rate ≥ 75% where this percentage was only 10% (p=0.011). An excess of iron and calcium reduces the good quality embryo rate, and an excess of potassium impairs the blastocyst rate. If potassium is above 237.18 mg/kg and calcium is below 147.32 mg/kg, these conditions favour embryo implantation. Pregnancy is influenced by high potassium and low copper levels. Controlling exposure to toxic elements is recommended for all couples with reduced fertility or receiving an ART.

Minerals and the Menstrual Cycle: Impacts on Ovulation and Endometrial Health

“…Zn aids hormone synthesis [37] by influencing LH, FSH [38], and steroid synthesis [39,40], and, along with Se [41,42], safeguards the oocyte from reactive oxygen species (ROS) damage [43,44]. In the luteal phase, Ca [45,46], Zn [47,48], Fe [49][50][51][52][53], and magnesium (Mg) [54,55] collectively support endometrial function [56]. Ca, deposited at the embryo implantation site, controls endometrial receptivity [45,46].…”

“…Ca, deposited at the embryo implantation site, controls endometrial receptivity [45,46]. Deficiencies in Fe [49][50][51][52][53] and zinc can impair this receptivity and hinder embryo implantation [47,48]. Mg, by relaxing smooth muscle [54], may influence retrograde menstruation [54,55] and reduce vascular endothelial growth factor, offering potential benefits for conditions like endometriosis [57][58][59].…”

“…Thus, ensuring appropriate iron levels is not only vital for general health but is also intricately linked to female reproductive success. There has also been a significant association between iron overdose and lower egg counts noted in assisted reproductive technologies (ART) studies [53,240].…”

“…In this context, iron can paradoxically play both protective and detrimental roles [23,321,322]. While adequate iron levels, supplemented in cases of deficiency, can increase oocyte quality [22], an excess can diminish it, augmenting the risk of compromised fertility [25,53].…”

The adverse role of endocrine disrupting chemicals in the reproductive system

“…The microenvironment provided by the follicular fluid (FF) affects the quality of oocytes. An excess of iron and calcium in the FF reduces the rate of good quality embryos, while an excess of potassium impairs the blastocyst rate ( 185 ). Increased use and improper disposal of hexavalent chromium (Cr), an environmental contaminant, can disrupt oocyte development in rats by elevating oxidative stress, causing DNA double-strand breaks, microtubule disruption, and aberrant chromosome segregation.…”