Q. I am 42 years old. I am considering another child. I have been thinking about this for two years now. I had some blood work done and tested positive for MTHR, I am taking folic acid and B6 and 12. Can I still go ahead with the baby? Is it much harder at this age to conceive, and any suggestions on when to conceive? Would appreciate your input. I had a miscarriage 2 years ago.
MTHR stands for Methylene Tetrahydro Folate Reductase, an enzyme which is present in the cells of our body. It is needed to metabolise and get rid of homocysteine. High homocysteine levels are a risk factor for blood clots in the veins (deep vein thrombosis, pulmonary embolism) or arteries (heart attack, stroke, arteriosclerosis). Some individuals have a variant of this enzyme, which is called thermolabile MTHR or C677T/MTHR caused by a single mutation of the MTHR gene. This variant does not metabolise homocysteine as well as the normal MTHR enzyme, and blood homocysteine levels in individuals with this variant enzyme may therefore be slightly higher than in individuals with the normal enzyme.
There are three likely possibilities - either one does not have the MTHR mutation, or one is heterozygous (1 variant gene), or homozygous (2 variant genes). It is only the homozygous mutation that is associated with elevated homocysteine levels. Nearly half the population may be MTHR heterozygous so it is nothing abnormal and does not cause elevation of homocysteine levels. Fasting homocysteine level should be measured and if normal, there is no need for vitamin B or folate therapy - even if the patient has the homozygous MTHR mutation. Individual with the MTHR mutation who have normal homocysteine levels are not at increased risk for clots. Elevated homocysteine levels may also be due to vitamin B and folate deficiency and renal failure. Often we do not know why levels are elevated.
Levels can be lowered by taking a multiple vitamin with a high content of folic acid, vitamin B6 (pyridoxine) and vitamin B12 (cobalamin). Often folate treatment alone lowers homocysteine levels sufficiently. Approximately 2 months after starting vitamins a homocysteine level should be checked again to make sure it has returned to the normal range.
Studies have demonstrated that over the age of 40 almost 50% of women will experience infertility as fertility in women decreases with advancing age. This age associated decline in fertility (and increase in miscarriages) is largely due to abnormalities in the egg itself, less frequent ovulation or to problems such as endometriosis, in which tissue similar to that lining the uterus attaches to the ovaries or fallopian tubes and interferes with conception.
The rate of miscarriage in older women is significantly greater than that in younger women. The increased incidence of chromosomal abnormalities contributes to this age-related risk of miscarriage. Women over age 40 have approximately a one in three chance of having a miscarriage in any given pregnancy. In addition, one in sixty live births are genetically abnormal. High rates of abnormal chromosome distribution are a major factor that can explain a lower rate of successful pregnancies in older women. There is also a greater chance of bearing twins. Women over 35 also have an increased risk of placental problems. The most common placental problem is placenta previa, in which the placenta covers part or all of the opening of the cervix. Fetal distress and a prolonged second stage of labour are more common in older mothers. There is also an increased risk of having a baby who is low birth weight or premature and increased risk of ectopic pregnancy (in which the fertilised egg implants outside the uterus, usually in the fallopian tube).
There are some special considerations for the older woman trying to conceive. These would include general health issues, since women over 40 are more likely to have medical problems e.g., diabetes, hypertension, heart disease — that can complicate a pregnancy. Therefore, an older woman contemplating a pregnancy should have a thorough medical evaluation, including a mammogram. Due to the increased incidence of genetic abnormalities in infants born to women over age 40, prenatal chorionic villus sampling or amniocentesis may be required. Even though older women face some special risks, many of these risks can be managed effectively with good prenatal care. It is important to keep in mind that the increased risk, even for the oldest women, is modest. Today, most women in their late 30s and 40s who are planning pregnancy can look forward to having a healthy pregnancy and a healthy baby.
You need to discuss all these issues with your obstetrician and plan your pregnancy. All the best.