Is there a perfect age to get pregnant? It's a question that's probably crossed your mind, particularly if your 30s are around the corner. But if you've put off having a baby until your 30s or 40s, you're in good company. In 1999, 23 percent of first births were to women over 30, compared with only 5 percent in 1975. In fact, the number of births to women ages 35 to 49 has tripled since the 1970s.

Fortunately, much of what we hear about potential risks, especially for expectant mothers older than 35, is unnecessarily alarming. The truth is that no matter what your age, you're very likely to have a healthy baby as long as you are in good health, seek early prenatal care, and adopt sound lifestyle habits. Here's what you can expect in your 20s, 30s, and 40s.

Pregnancy In your 20s
Healthy women in this age range usually have it pretty easy when it comes to pregnancy; it's no wonder they have the most babies! They often conceive within about two months of trying, have a relatively low risk of miscarriage (about 10 percent), and have the fewest medical complications during pregnancy. Some other perks of having a child in your younger years include a low risk of Down syndrome or other chromosomal birth defects and, for reasons not entirely understood, a low risk of giving birth via cesarean section.

However, in some instances, younger is not always better. Women ages 20 to 24 have a slightly higher risk of preeclampsia, a dangerous pregnancy condition that causes high blood pressure and protein in the urine, than women in their middle 20s and early 30s. This is largely due to the fact that women in their early 20s are most likely to be having their first baby, which is a risk factor for the condition. Doctors are unsure why some women get preeclampsia, and the condition is a serious one. It can lead to a slowdown of fetal growth and preterm delivery.

Women in their early 20s also have a greater chance than those in their late 20s and early 30s of having a low birth weight baby, largely because of poor health habits. For example, women ages 20 to 24 are more likely to smoke than women 25 and older, and smoking doubles the risk of having a low birth weight baby. Young women are also more likely to have a poor diet, delay prenatal care, and gain less than the recommended amount of weight (25 to 35 pounds for women of normal weight) — all of which increase the risk of having a baby who is underweight. Low birth weight babies also have a greater chance of health problems as well as lasting disabilities. Fortunately, reducing your risk is simple: Eat well, take a complete vitamin, and seek good prenatal care.

Pregnancy In Your 30s
Many women feel that waiting until this stage of life to have children is ideal, since they're more confident and financially secure. And if you're in your early 30s, your pregnancy risks differ little from those of a woman in her 20s. However, pregnancy at this age does have its difficulties. For one thing, it may take you longer to conceive than a younger woman because you ovulate less frequently. Fertility tends to decrease slowly after age 30, and your chance of giving birth to a child with Down syndrome or another chromosomal defect increases.

You've probably heard that 35 is a benchmark age when it comes to pregnancy problems and declining fertility. Actually, most women 35 and older have healthy babies, but studies suggest that they may have more problems along the way. First, fertility begins to decrease more rapidly after age 35, making it harder to conceive. According to statistics from the American Society for Reproductive Medicine, about one-third of women older than 35 have issues with fertility. If you are 35 or older and you have not been able to conceive after six months of trying, consult your doctor. Many fertility problems can be successfully treated.

Women in this age group are also more likely to suffer a miscarriage than younger women. In fact, a recent Danish study discovered that more than 20 percent of pregnant women ages 35 to 39 miscarried.

If you're 35 or older, you'll probably be offered amniocentesis, a test used to diagnose Down syndrome and other chromosomal abnormalities. The test isn't offered to everyone because it poses a small risk of miscarriage; 35 is the cutoff age for amnio because it's the age at which the risk of having a Down's baby (one in 378) is about equal to the chance of the test causing a miscarriage. Some women choose to have the amniocentesis; other opt for a blood test called a triple screen, along with an ultrasound, to help define their risk of having a Down's baby before going forward with an amnio.

Women older than 35 are also more likely to have problems such as preeclampsia, diabetes, premature birth, and a low birth weight baby, as well as placental problems during pregnancy. The most common of these is placenta previa, in which the placenta covers part or all of the opening of the cervix. This condition can cause severe bleeding during delivery, but complications can usually be prevented with a cesarean section. Luckily, most of the other potential problems can be remedied with proper medical treatment and good prenatal care.

Pregnancy In Your 40s
Today it is not unusual for women in their 40s to be giving birth for the first time. Unfortunately, conception may be difficult; more than 50 percent have difficulties conceiving. The pregnancy risks of a 40-something woman are similar to those of a woman in her late 30s. The two risks that increase most markedly in your 40s are chromosomal abnormalities, such as Down's (the risk is one in 100 at age 40 and one in 30 at age 45) and miscarriage: According to the Danish study, the risk of miscarriage reaches about 50 percent by age 42.

Women at this age are also almost three times as likely to develop diabetes during pregnancy than moms in their 20s. You may also have more problems during delivery, such as failure to progress and fetal distress, which may help explain why first-time moms older than 40 have the highest risk of c-section — 43 percent, according to a recent study conducted at Harvard Medical School.

Pregnancy Advice for All Ages
Regardless of statistics, whatever your age, there are steps you can take to improve your chances of having a healthy baby.

• See your health-care provider for a prepregnancy visit. This is especially crucial if you have chronic health problems such as high blood pressure or diabetes. Your provider can make sure that any medications you take for these conditions are safe during pregnancy.
• Take a vitamin containing 400 micrograms of folic acid daily. Start before you become pregnant and continue throughout the first month of pregnancy to help prevent certain serious birth defects of the brain and spinal cord.
• Get early and regular prenatal care. Working with a health-care provider to come up with a game plan for a healthy pregnancy will go a long way toward keeping you and your baby safe and sound.

Richard Schwarz, MD, obstetrical consultant to the March of Dimes, is past president of the American College of Obstetricians and Gynecologists; chairman of the department of obstetrics and gynecology at New York Methodist Hospital in Brooklyn; and a professor of obstetrics and gynecology at Cornell University Medical College in New York City.

The information on this Web site is designed for educational purposes only. It is not intended to be a substitute for informed medical advice or care. You should not use this information to diagnose or treat any health problems or illnesses without consulting your pediatrician or family doctor. Please consult a doctor with any questions or concerns you might have regarding your or your child's condition.

Content courtesy of American Baby.