It's been your dream, giving birth to a healthy, happy baby. Pregnancy is as natural as the birds and bees, but in today's world it takes planning to make sure things go well.

If you've been taking your health for granted -- getting by on little sleep, hitting the martini bars, forgetting dental exams -- it's time to assess your lifestyle and make some changes.

To give your baby the healthiest beginning, take steps in the months before you conceive, says Connie Graves, MD, director of maternal-fetal medicine at Vanderbilt University School of Medicine in Nashville, Tenn. "You want to start with a very healthy body, and you want to minimize risk factors that can hurt the baby or hurt you."

By making healthy lifestyle changes, you may even boost your odds of getting pregnant. "One of my patients just had her third child at age 42," Graves tells WebMD. "She's a perfect example that maintaining a healthy lifestyle will help preserve fertility and assist conception."

Pregnancy: The Critical First Weeks of Life

By the time you learn you are pregnant, your baby is probably 2 to 4 weeks old -- a tiny placenta and embryo attached to your uterine wall. During these critical weeks, your baby's development can be greatly affected by health and lifestyle issues like:

• Folic Acid: It's long been known that folic acid prevents the serious birth defect called spina bifida (a baby born with a spine that is not closed). Fortunately today many food items, such as bread, bagels, and breakfast cereal, are fortified with folic acid to help women of childbearing age reduce risk of this birth defect.

• Alcohol and smoking: Alcohol has been linked to premature delivery, mental retardation, birth defects, and low-birth-weight babies. Smoking can decrease the likelihood of conception -- and increase the risk of preterm labor and low birth weight.

• Over-the-counter and prescription drugs could also affect your baby's health. For example, during the last few months of pregnancy NSAIDs -- such as aspirin, aspirin compounds (Anacin, Bayer, Bufferin), and ibuprofen (Motrin, Advil) -- can cause a decrease in the amount of amniotic fluid (the fluid cushioning the baby) and cause closure of the ductus arteriosa, an important blood vessel in the baby.

• Illegal drugs have their own risks. Cocaine use, for example, can be detrimental and life-threatening to both mother and baby.

• Gum disease can increase the risk of preterm delivery up to eightfold, research shows. Babies born to mothers with periodontal infections are twice as likely to be admitted to a neonatal intensive care unit, and three times more likely to need hospitalization beyond seven days, the CDC reports.

Obesity, Diabetes, and Your Baby

Obesity is an especially critical issue for women of childbearing age, says Michael Greene, MD, director of obstetrics at Massachusetts General Hospital in Boston.

"Obesity is associated with many complications, because it greatly increases a woman's risk of developing high blood sugar and diabetes -- either before they get pregnant or during their pregnancy," he tells WebMD.

When a fetus is exposed to the mother's high blood sugar early on -- before 13 weeks old -- there is a serious risk of birth defects.

"A mother's obesity and uncontrolled blood sugar puts her baby at high risk for a variety of congenital malformations, including defects of the brain and spinal cord," Greene explains.

And babies of mothers who have diabetes are likely to grow large in size, fed by excess sugar that makes its way into the placenta. "These large babies can be difficult to deliver vaginally, and may require cesarean section," Greene says.

Obesity, high blood pressure, and asthma also put a mother at high risk for developing preeclampsia , Greene tells WebMD. This condition prevents the placenta from receiving enough blood, which can cause the baby to be small. These babies are often born prematurely, which carries its own complications, like learning disabilities. The babies are also at risk for birth defects and death, he adds.

A Healthy Pregnancy: The Right Steps

At least three months before trying to get pregnant, women should see either a doctor or midwife, Graves advises. It's called preconception counseling, and it helps women know the steps they must take to ensure a healthy pregnancy. "A doctor can help make sure everything is in order," she tells WebMD.

To help get everything in order, you'll want to start with:

Your health: If you have chronic medical problems like obesity , diabetes , high blood pressure , or asthma , you must get them under control before you become pregnant. If you need to lose weight, this is the best time to do it -- not after you become pregnant.

Depression is another problem that can affect your pregnancy. If you are depressed when you become pregnant, you are more likely to use tobacco, alcohol, and illegal drugs which can harm your baby. You may also have difficulty bonding with your baby and experience postpartum depression, which is higher in women with a history of depressive illness.

To get help, talk to your friends, your partner, your family -- and if that isn't enough, consider therapy and possibly antidepressants. While recent research shows antidepressants may pose small risks to the fetus, many doctors believe a depressed mother isn't healthy for a fetus or a baby -- and encourage women to take antidepressants during pregnancy if they need them. Your doctor can help you decide what's best for you.

It's also important to share with your doctor your family history, including incidence of twins, mental retardation, blindness, deafness, cystic fibrosis , congenital birth defects, Tay-Sachs disease, sickle trait/sickle cell, and thalassemia.

Prenatal vitamins: Take a daily multivitamin that contains 400 milligrams of folic acid; you can buy these over the counter. Eat breakfast cereals fortified with folic acid -- as well as green leafy vegetables, nuts, beans, and citrus fruits, which naturally contain folic acid.

Diet: If fast food, sodas, and sweets are your mainstays, change your ways, Graves advises. Eating a healthier, well-balanced diet will boost your overall health and -- once you conceive -- provide your baby with the vitamins and minerals necessary for development.

Get at least four servings of dairy products and calcium-rich foods daily; get at least one serving of foods rich in vitamin C, vitamin A, and folic acid daily. Avoid excessive vitamin A, which may be associated with birth defects.

Do not eat:

• Shark, swordfish, king mackerel, or tilefish (also called white snapper), because they contain high levels of mercury. Avoid raw fish and shellfish like oysters and clams.
• Soft cheeses like feta, Brie, Camembert, blue-veined, and Mexican-style cheese – which are often unpasteurized and may cause Listeria infection. The "safe" cheeses are hard cheese, processed cheese, cream cheese, cottage cheese, or yogurt.
• Saccharin, because it crosses the placenta and is stored in fetal tissues. However, other FDA-approved sweeteners (Equal, NutraSweet, Splenda) are acceptable during pregnancy .

Limit caffeine to no more than 300 milligrams daily – about two 8-ounce cups of coffee a day. Be careful that you're not getting additional caffeine in soft drinks, tea, or chocolate. Caffeine may affect blood flow to the uterus, which could affect the developing fetus.

Alcohol, tobacco, illegal drugs: If your lifestyle includes these, quit, as they pose serious risks to a fetus. Get advice from your doctor if you have trouble quitting.

Dental issues: Get your teeth cleaned regularly to control gum disease. If you need other dental work, Graves advises getting it done before getting pregnant. Your gums are likely to bleed more during pregnancy since your body is generating more blood flow, she says.

Medications: If you're taking a medication for a chronic condition, talk to your doctor. Some medications are considered safe during pregnancy. Others are known to potentially raise the risk of birth defects -- like the blood pressure drugs known as ACE inhibitors. With some medications, like those sold over the counter, the effects on an unborn child are often unknown. Your doctor can help you weigh the risks and benefits.

Vaccinations: Your immunizations may need to be updated, so check with your doctor about this. Timing of these shots is critical if you're planning on getting pregnant since some vaccines can be harmful to the baby. With measles , mumps, rubella (MMR) and chickenpox vaccines, you must have the shot -- and use birth control -- for one to three months prior to conception, says Graves.

Other vaccines like tetanus or hepatitis B shots can be given during pregnancy. In fact, women who will be in their second or third trimesters during the flu season should get flu shots. Your doctor can help you figure out what vaccines you need and when it's safe to get them.

Stress reduction: It is not fully understood, but the cortisol hormone that the body releases during times of stress seems to make conception more difficult, says Graves. "Stress is difficult to avoid, but exercise, getting plenty of sleep, and developing a good support system can help reduce stress."

If you've stayed true to a healthy lifestyle over the years, it can translate into a healthy pregnancy -- especially helpful if you're past the "prime" fertility years, says Graves.