Decreasing the chance of birth defects: most birth defects occur in the first three months of pregnancy, when the organs are forming - includes related article on Accutane

FDA Consumer, Nov, 1996 by Rebecca Williams

When Tammy Troutman of Knoxville, Tenn., was planning her first pregnancy, she had a good reason to be concerned about birth defects.

Born with a mild form of spina bifida, Troutman worried her child would also have the condition. So she did what health-care experts say is the best first step toward preventing birth defects: She visited her physician for an exam well before she and her husband tried to conceive.

"Before I decided to have children, I went to the doctor to make sure everything would be OK," Troutman remembers.

He advised her to take a daily multivitamin supplement containing folic acid, a B vitamin that would decrease her chances of having a baby with spina bifida. Troutman took the vitamins for five months before conceiving her son, Evan, who was born in August 1993 with a normal, healthy spine.

"Even if he had been born with spina bifida," Troutman says, "I felt secure knowing that I had done everything I could to prevent it."

Of the 4 million infants born annually in the United States, about 3 to 5 percent are born with birth defects, according to the March of Dimes. Birth defects account for 20 percent of all infant deaths in the United States, more than from any other single cause.

For the majority of birth defects, the cause is unknown," says Franz Rosa, M.D., a pediatrician with the Food and Drug Administration who monitors reports of prescription drugs causing birth defects. Rosa cites a list of drugs that are known to be birth-defect causing, but he says they only account for a small percentage of all malformations.

"There's a lot we just don't know," Rosa says. "Most birth defects are not preventable and mothers should not feel guilty about causing defects that they really didn't. Worrying too much is not good for pregnancies."

What experts do know is that most birth defects occur in the first three months of pregnancy, when the organs are forming. It is in these crucial first few weeks - often before a woman even knows she's pregnant - that an embryo is most susceptible to teratogens, substances that can cause defects. However, some birth defects do occur later in pregnancy as well.

"The key is what your life is like at the time you become pregnant," says Deborah Smith, M.D., an obstetrician and gynecologist in FDA's Office of Women's Health. "Are you getting enough folic acid, are you immune to rubella, are you avoiding alcohol and smoking? These are some of the things we know are important."

Despite the benefits of seeing a doctor before conceiving, only 26 percent of women planning a pregnancy do so, according to the March of Dimes. Furthermore, health experts estimate more than 50 percent of pregnancies are unplanned. That's why a healthy lifestyle for all women who could become pregnant - even if they don't intend to - is the best way to minimize the risk of birth defects.

Healthy Diet

The maxim "You are what you eat" is sterling advice during the first three months of pregnancy.

Studies of women who had endured starvation during World War II illustrate the importance of diet early in pregnancy. Contrary to what researchers expected, it was not the babies born during food deprivation that had the most malformations, but those conceived during food deprivation.

One nutrient known to prevent birth defects is folic acid, the B vitamin Tammy Troutman took before her pregnancy. Folic acid is the chemical form of folate, which is found in green leafy vegetables, citrus fruits, and legumes. Folate aids in cell division, and taking extra folic acid reduces a woman's chance of having a child with spina bifida and other abnormalities of the spine and brain.

Spina bifida occurs when the vertebrae do not close completely. It is one of several conditions known as neural tube defects, because the neural tube is the portion of the embryo that develops into the brain and spinal column. In very mild cases, spina bifida causes few or minor problems, but in more severe cases, the spinal cord protrudes through the vertebrae into a sac outside the child's body. This impairs the child's mobility and other neurological functions and requires surgery to repair the opening.

To help prevent neural tube defects, the U.S. Public Health Service has recommended that all women of childbearing age who are capable of becoming pregnant consume 0.4 milligrams (mg) of folic acid per day. (For pregnant or lactating women, the daily value increases to 0.8 mg per day.) It is especially important that women take in sufficient folate before they become pregnant.

FDA recently published regulations requiring manufacturers to add folic acid to enriched grain products such as flour, noodles, bread, rolls, buns, farina, cornmeal, grits, and rice by January 1988. (See "How Folate Can Help Prevent Birth Defects" in the September 1996 FDA Consumer.)

Although the main challenge in pregnancy is getting enough nutrients, too much of a good thing is not good for a developing baby, either. Vitamins A and D are the most notable examples. Both can be toxic at levels higher than the recommended daily allowance. Such levels are rarely reached through food intake; however, women taking dietary supplements need to be aware of this risk and the amount of these vitamins they are taking. Women who take vitamin and mineral supplements should discuss with a health-care professional what vitamins are safe to continue taking during pregnancy.