Pregnancy is a magical time. Women in their thirties may feel they might have missed out on some of that magic. This is not true according to the March of Dimes. Women in their 30s and 40s often have healthy pregnancies and healthy babies, and the rate of pregnancies for women of these ages continues to rise.

However, women who postpone childbearing may face some special risks. Generally, women have decreased fertility starting in their early thirties and it's not unusual for a woman in her mid-thirties to take longer to conceive than a younger woman.

A decrease in ovulation can be the result of 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.

Other problems may accumulate with age. Conditions such as diabetes and high blood pressure are more common in older women and may endanger a pregnant woman and her developing baby. She may also face a higher risk of placental and bleeding problems during pregnancy, as well as risk of cardiovascular problems.

Risk of Miscarriage
Most miscarriages occur in the first trimester of pregnancy. According to the March of Dimes, rate of miscarriage in older women in significantly greater than that of young women. Studies show that this risk is 12 to 15 percent for women in their twenties and rises to about 25 percent at age 40. The increased incidence of chromosomal abnormalities contributes to the age-related risk of miscarriage.

Risk of Birth Defects
The risk of certain chromosomal disorders increases as a woman ages. The most common of these is Down syndrome, a combination of mental retardation and physical abnormalities caused by the presence of an extra chromosome 21. At age twenty-five a woman has a 1-in-1250 chance of having a baby with Down syndrome. At age 35, the chance increases to 1-in-378 and at age 40 it's 1-in-106.

Many women who are 35 or older have prenatal testing, such as amniocentesis or chorionic villus samples, to rule out Down syndrome and other chromosomal abnormalities. If prenatal testing rules out any defects and the mother is healthy, the baby is likely at no greater risk of birth defects than if the mother were in her twenties.

First-time mothers over 30 are also more likely than women in their early twenties to have difficulty during labor. This may account for an increased rate of cesarean sections among women over 30.
The good news is that advances in medical care have made late-age pregnancy safer. And there are steps a pregnant woman can do to reduce her risks. These include:

 - Consume 400 micrograms (0.4 milligram) of the B vitamin folic acid daily before and during pregnancy (this applies to all women of childbearing age).

 - Have a pre-pregnancy medical check-up and obtain early and regular prenatal care during pregnancy.

 - Eat a variety of nutritious foods and achieve proper weight for height before conception.

 - Don't drink alcoholic beverages during pregnancy.

 - Don't smoke during pregnancy.

 - Don't use any drug, even over-the-counter medications, unless recommended by a health care provider who knows you are pregnant.

   Dr. Marimon is a diplomate of the American Board of Obstetrics and Gynecology and is a board-certified obstetrician affiliated with Hialeah Hospital.

For more information on having a healthy baby, visit the March of Dimes web site at www.modimes.org.