MTHFR mutations have been linked in some studies to an increased chance of having a baby with a neural tube defect (spina bifida). One study suggested that mothers with 2 MTHFR mutations were twice as likely to have a baby with a neural tube defect, whereas other studies have not supported this finding. Recent research has implied that risks vary, based on the nutritional status of the mother (ie, folate levels, vitamin intake) and whether or not she has an elevated homocysteine level. Because of this controversy, some practitioners may recommend extra folate supplementation (usually 4 mg) for women with 2 MTHFR mutations, whereas other practitioners will recommend normal use of prenatal vitamins containing folic acid for a woman who does not have an elevated homocysteine level.
There is also conflicting evidence about the relation between homozygous MTHFR mutations and pregnancy complications (including preeclampsia, placental abruption, recurrent pregnancy loss, and intrauterine growth restriction, as described earlier). A recent meta-analysis, which combined all of the data from these studies, found that there was not an association between MTHFR and recurrent pregnancy loss. It seems that homozygous MTHFR may moderately increase the risk of preeclampsia and placental abruption, but more research in this area is necessary. Although it is not standard medical practice to test for MTHFR mutations when a woman has a history of these complications, some practitioners may order this testing.