Can Folic Acid Lower the Risk of Having a Baby with Down Syndrome?

Understanding Down Syndrome

Down syndrome is a genetic condition that occurs when an individual has an extra full or partial copy of chromosome 21. This additional genetic material alters the course of development and causes characteristic features and medical problems associated with Down syndrome. Down syndrome is the most common chromosomal condition, occurring in approximately 1 in 700 babies born each year in the United States.

Causes of Down Syndrome

In the majority of Down syndrome cases (about 95%), there is an extra copy of chromosome 21 in all of the body's cells. This form is known as trisomy 21. Instead of the normal pair, there are three copies of chromosome 21. This extra genetic material is responsible for the characteristic features and health problems associated with Down syndrome.

In a small percentage of cases (about 3-4%), Down syndrome is caused by a Robertsonian translocation, which occurs when the long arm of chromosome 21 breaks off and attaches to another chromosome. The translocated chromosome 21 material is present in all cells, causing the features of Down syndrome. Carriers of balanced Robertsonian translocations involving chromosome 21 are at increased risk for having children with Down syndrome.

The final type is called mosaic Down syndrome and accounts for only about 1-2% of cases. In mosaic Down syndrome, there is a mixture of two types of cells, some containing the normal two copies of chromosome 21 and others containing three copies (trisomy 21). The individual's physical features and problems related to Down syndrome depend on the percentage of cells with the extra chromosome 21 material.

Risk Factors for Down Syndrome

Advanced maternal age is the only well-documented risk factor for Down syndrome. A woman's chances of having a child with Down syndrome increase with age because older eggs have a greater risk of improper chromosome division. By the age of 35, a woman's risk is about 1 in 350. By age 40, the risk is about 1 in 100, and by age 45, the risk is about 1 in 30.

However, the majority of children with Down syndrome are born to women under age 35, because younger women have far more babies. About 80% of children with Down syndrome are born to women under 35 years of age.

A woman who already has one child with Down syndrome has an increased risk (about 1%) of having another child with Down syndrome. In rare cases (about 1-2%), Down syndrome occurs because of a defect in the father's sperm cells. In general, the risk of having a child with Down syndrome is not influenced by environmental factors.

Can Taking Folic Acid Reduce the Risk of Down Syndrome?

Folic acid is a B vitamin that is very important for preventing birth defects of the brain and spine called neural tube defects. Many health organizations recommend that all women who could become pregnant take a daily multivitamin containing 400 micrograms of folic acid.

Some research has suggested that taking folic acid before and during early pregnancy might also help reduce the risk of having a baby with Down syndrome. So far, results have been mixed, but here is a summary of what studies have found:

How Folic Acid Helps Prevent Birth Defects

In order for a baby to develop properly, hundreds of thousands of cell divisions need to occur in a very precise manner. Folic acid helps facilitate this cell division and growth.

Without adequate levels of folic acid, cell division is disrupted and too few or too many cells are made. This can result in a baby being born with a devastating birth defect of the brain (anencephaly) or spine (spina bifida). Anencephaly is fatal, and spina bifida causes varying degrees of paralysis.

Getting adequate folic acid before pregnancy helps ensure that a baby's brain and spine develop normally. Folic acid is the most important vitamin related to reducing neural tube defects. The United States saw a 27% decline in the number of neural tube defect-affected pregnancies after fortification of grains was implemented in 1998 to increase folic acid levels in commonly eaten foods.

Studies on Folic Acid and Down Syndrome

Several studies have suggested that taking folic acid supplements before and during early pregnancy may offer some protection against having a baby with Down syndrome:

• A 2015 meta-analysis combined data from 10 studies involving 8,665 Down syndrome cases. It found a significant 38% reduction in risk of Down syndrome in women who took folic acid supplements.
• A 1999 Hungarian study found that women who took multivitamins containing 800 mcg of folic acid per day had a significantly lower chance of having a child with Down syndrome compared to women who did not take supplements.
• A 2018 Danish study analyzing data from over 900,000 pregnancies found that women who took folic acid supplements around conception had a 19% lower risk of having a baby with Down syndrome compared to women who did not take folic acid.

However, other studies have not found a protective effect of folic acid against Down syndrome:

• A 2022 study of over 10,000 pregnancies did not find a link between folic acid supplementation and risk of Down syndrome.
• Other analyses have found no correlation between blood folate levels during pregnancy and risk of Down syndrome.

Currently, taking folic acid supplements is only scientifically proven to help prevent neural tube defects, not Down syndrome. More research is needed on the effects of folic acid and Down syndrome risk.

Should I Take Folic Acid to Prevent Down Syndrome?

Even though the evidence is inconclusive right now, taking a daily multivitamin with 400 mcg of folic acid before pregnancy is recommended for all women because it helps prevent devastating neural tube defects. This advice comes from the US Preventive Services Task Force, the Centers for Disease Control and Prevention (CDC), and the American College of Obstetricians and Gynecologists (ACOG).

The research indicating folic acid may also lower Down syndrome risk, even slightly, provides extra motivation to take a supplement. Folic acid and other basic vitamins are very safe even in high doses.

Make sure to start taking folic acid at least 1 month before pregnancy. If you find out you are already pregnant, start taking the supplement right away to maximize protection.

Talk to your doctor about the right folic acid or prenatal vitamin supplement and dosage for you based on your health history and any other medications you take. While trying to conceive and during pregnancy, aim for at least 400-800 mcg of folic acid per day from supplements and folate obtained through a healthy diet.

What Else Can Reduce Down Syndrome Risk?

Because advanced maternal age is the only definitive risk factor, women who want to lower their chances of having a baby with Down syndrome are advised to have children at younger ages. By age 30, a woman's risk is about 1 in 900. By 35, the risk jumps to about 1 in 350.

Some companies offer prenatal screening that can estimate the risk of Down syndrome early in pregnancy. There are also diagnostic tests like amniocentesis and chorionic villus sampling that can indicate whether the baby has Down syndrome with about 99% accuracy.

However, there is no guaranteed way to prevent Down syndrome. Having a child with Down syndrome can happen at any maternal age and to any family.

The only way to definitively diagnose Down syndrome during pregnancy is through prenatal diagnostic testing. Some parents may choose to terminate a pregnancy if Down syndrome is confirmed, but many families happily welcome a baby with Down syndrome into their lives.

Early intervention services, education support, improved healthcare, and public awareness are helping individuals with Down syndrome live increasingly full lives. Many adults with Down syndrome are able to work, have relationships, and live independently with some assistance.

The Bottom Line

There is some promising but inconclusive research that taking folic acid supplements before and during early pregnancy may reduce the risk of having a baby with Down syndrome. However, folic acid is proven to greatly lower the risk of devastating neural tube defects of the brain and spine.

All women who could become pregnant are advised to take a daily multivitamin with at least 400 mcg of folic acid. If you find out you're pregnant and haven't been taking folic acid, start immediately. To maximize prevention of neural tube defects and possibly lower Down syndrome risk, aim for at least 400-800 mcg of folic acid per day from supplements and folate-rich foods.

Talk to your doctor about the right folic acid or prenatal vitamin for you. Advanced maternal age is the only confirmed risk factor for Down syndrome, so having children earlier provides the best odds. However, due to improved education, healthcare and integration, individuals with Down syndrome are living happier, healthier, more independent lives than ever before.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.