MTHFR *can* be a risk factor for pregnancy complications including preeclampsia. MTHFR is a gene mutation. 50% of the population has the mutation on one allele or one copy of the gene (we get a set of genes-one from each parent). These folks are considered heterozygous for the mutation and usually don't have issues with pregnancy because of the gene mutation. Those with the mutation on both alleles (or both copies of that gene) have a higher risk because the mutation on both alleles (heterozygous), can cause an increase in homocysteine levels, which can cause some to clot more readily, especially when added to pregnancy which causes women to be hypercoaguable. Additionally, these women often have a hard time processing/absorbing folic acid. Women with the double gene mutation are often prescribed extra folic acid and other b vitamins, some get low dose aspirin, and fewer yet get lovenox. It depends on other risk factors. And of course, lovenox is not a miracle cure and has risks that should be carefully considered. This is the non-scientific explanation, but if I were homozygous for MTHFR, I'd ask to have my homocyteine and folic acid levels checked-as those are the potential culprits . Genetics is a funky science that most docs only have a basic understanding in that may glance over the fact that the double mutation may increase clotting tendencies especially when added to a hypercoaguable state such as in pregnancy.