The association of parental methylenetetrahydrofolate reductase polymorphisms (<i>MTHFR</i> 677C&gt;T and 1298A&gt;C) and fetal loss – A case-control study in South Australia

<b>Objective:</b> To determine the association between parental MTHFR 677C > T (RS1801133) and 1298A > C (RS1801131), and fetal loss (FL).<b>Design:</b> Case-control study.<b>Setting:</b> Department of Obstetrics and Gynecology, Lyell McEwin Hospital (LMH), and the Women's and Children's Hospital (WCH) in Adelaide, Australia.<b>Patients:</b> A total of 222 couples with FL and 988 couples with uncomplicated pregnancies.<b>Measurements:</b> The main outcomes were FL and hyperhomocysteinemia (HHcy). All couples were tested for MTHFR 677C > T and 1298A > C. Fasting homocysteine was measured in the women with FL.<b>Results:</b> The main finding was a significant difference between the FL group and controls in couples with ≥4 abnormal alleles compared to <4 [p=.0232, OR 1.9 (95% CI 1.1-3.3)]. None of the couples with FL had zero abnormal alleles (both parents 677CC/1298 AA). However, this was also rare amongst the controls. Maternal carriage of both 677C > T and the 1298A > C polymorphisms was similar between the FL group and controls. The prevalence of paternal 677TT/1298AA and 677CC/1298AC was significantly higher in the FL group compared with controls. HHcy was significantly more common in the FL group compared with controls.<b>Conclusion:</b> The presence of parental MTHFR 677C > T and 1298A > C is associated with FL. The association between maternal MTHFR genotypes with FL is less pronounced than in previously published articles investigating first trimester miscarriages. Maternal HHcy is a significant risk factor for FL.