Blood Test May Help Prevent Neural Tube Defects

Folate concentrations can help doctors and moms monitor folic acid intake

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Pregnant women require various extra nutrients to help their unborn babies grow. But one of these nutrients may be more important than others.

Folate helps prevent defects in the neural tube, which becomes the baby's spinal cord. A recent study determined what blood levels of folate most effectively reduced the risk of neural tube defects.

Sufficient folate helps prevent conditions like spina bifida and others caused by a neural tube that does not close properly by the 28th day of pregnancy.

The findings of the study, from the US Centers for Disease Control and Prevention (CDC), might be able to help doctors determine whether women are getting enough folate while pregnant.

"Ask your OB-GYN about folic acid supplements."

The study, led by Krista Crider, a geneticist with the National Center on Birth Defects and Developmental Disabilities at the CDC, aimed to figure out what the appropriate blood levels of folate were to prevent neural tube defects.

The researchers looked at the data from two trials involving a total of 249,025 Chinese women.

In one of these trials, 1,194 women were assigned to take either 100 micrograms per day, 400 micrograms per day, 4,000 micrograms per day or 4,000 micrograms per week of folic acid — or else a placebo (fake pill) — while using contraception and neither pregnant nor breastfeeding.

These women underwent blood tests to determine how much folate was in their blood during the trial.

The other trial, involving the rest of the women, encouraged all of them to take 400 micrograms per day while attempting to conceive and through their first trimester.

The researchers recorded the amount these women took and any birth defects among their children. Then, they analyzed the data.

They found that the risk of neural tube defects decreased as the blood folate levels increased. The tipping point appeared to be a concentration of 1,000 nanomoles per liter of folate in the red blood cells.

The measurement of nanomoles per liter (nmol/liter) is one that a doctor can test during women's prenatal check-ups. Above 1,000 nmol/liter, the neural tube defect risk appeared to taper off.

For example, six neural tube defects per 10,000 births occurred with blood levels of 1,050 to 1,340 nmol/liter. By comparison, the rate of neural tube defects was 25 per 10,000 when folate blood levels were 500 nmol/liter.

Ideally, then, women's blood levels of folate should be above 1,000 nmol/liter to reduce the risk of neural tube defects, according to the study findings.

According to Andre Hall, MD, an OB-GYN at Birth and Women's Care in Fayetteville, NC, the Food and Drug Administration requires all prenatal vitamins to include folate.

"This is because of the link between folate and the decreased incidence of neural tube defects," Dr. Hall said. "It is important however, that women start increasing their folate levels before they get pregnant as by the time most women realize they are pregnant, the neural tube (spinal cord) has already developed into whatever manner it's going to develop. This study further reinforces the upside of increased levels of folate with no real known downside."

The study was published July 29 in the journal BMJ. The CDC funded the research.

The authors reported no conflicts of interest.

Review Date: 
July 31, 2014
Last Updated:
August 1, 2014