How are tTG IgA and fertility related?

The provided knowledge context does not contain direct information on the relationship between tTG IgA (tissue transglutaminase IgA) and fertility. tTG IgA is a well-established serological marker for celiac disease, an autoimmune condition that, if untreated, is associated with infertility, recurrent miscarriage, and pregnancy complications. However, the given contexts focus on vitamin D status, gut microbiome testing, and MTHFR variants—not on celiac disease or fertility. Therefore, the evidence from these sources is unclear. For a reliable answer, specific studies on tTG IgA and fertility would be required. Conservatively, a positive tTG IgA test warrants medical evaluation, especially when planning pregnancy.