January is National Birth Defects Prevention Month, so it is an appropriate time to recognize and share the knowledge that some steps can be taken to prevent certain birth defects.
Folic acid (4 mg daily for women with prior history of neural tube defect; 400 micrograms daily for all others, including women with MTHFR polymorphisms) can prevent neural tube defects (e.g. spina bifida, anencephaly). It is best to start the folic acid before pregnancy since the neural tube completes development very early in pregnancy, sometimes before pregnancy is suspected. Women should check the vitamin they are taking to ensure adequate folic acid content; if not, additional folic acid supplementation can be added.
Controlling diabetes and thyroid disease before pregnancy can also prevent many associated birth defects. Hypothyroidism can affect brain development. Uncontrolled diabetes can cause birth defects, including cardiac and neural tube defects, so it is important for diabetic women to have good glucose control before becoming pregnant.
A number of medications, such as ACE inhibitors (usually given for hypertension), valproic acid (usually given for seizure disorder), tretinoin (used for acne), and warfarin (usually given to prevent blood clotting), can cause birth defects and alternative therapies should be considered before pregnancy. Patients should always consult their health care provider before stopping any medication.
Women should also get vaccinated before pregnancy or avoid exposure to certain infections that can cause birth defects, including measles, mumps, rubella, varicella, herpes, syphilis, and cytomegalovirus. While exposure to high-dose radiation is a known cause of birth defects, the radiation exposure from the typical X-ray imaging is lower than the threshold that can cause birth defects. Thyroid treatment with radioiodine or other radioisotopes is contraindicated in pregnancy. Because these isotopes can remain in the body for various lengths of time, depending on the type of isotope used, women are usually advised to avoid pregnancy for several months after such treatment. Women should consult with their health care provider before undergoing any treatment or testing that involves exposure to radiation.
Finally, various substances, including nicotine, alcohol, marijuana, cocaine, and others, can have significant effects on formation and development of various organs in the baby. Addressing substance use/abuse is most beneficial before pregnancy, but cessation after pregnancy is diagnosed can still improve outcomes.
Given all the conditions that can impact pregnancy outcomes and risk of births defects, it is important that women who are trying to become pregnant review their medical and family history with their health care provider before conception, including genetic history for both the mother and father. This is sometimes referred to as preconception counseling. Some women may also benefit from genetic counseling, laboratory testing, or imaging before pregnancy or early in pregnancy, including ultrasound and genetic testing. For couples who already know they have a genetic condition that can be passed to their future children, they can discuss in-vitro fertilization and preimplantation genetic diagnosis (PGD) with their physician.