If you have either an acute or a chronic disease -- anything from asthma to cancer -- careful pre-pregnancy planning is especially important. Any medical condition that can affect you when you're not pregnant may have a significant effect on your pregnancy. Unfortunately, as women delay childbearing the passage of time makes them more likely to develop a chronic disease. Remember that the course of the disease may be affected adversely as your body undergoes the dramatic changes of pregnancy, and, conversely, some medical conditions put you into a higher risk category for pregnancy.

Some diseases or their treatment, such as diabetes and epilepsy, may increase the risk of miscarriage or birth defects. Heart disease and urinary tract infections may cause premature labor or result in poor growth of the fetus. Hypertension may cause fetal distress or abruptio placenta, in which the placenta separates from the uterus and threatens the fetus's oxygen supply. Both you and your medical practitioner must constantly be aware of the fact that there are two patients: the mother and the fetus.

When you become pregnant, your body changes drastically. Your shape changes, your size increases, your ankles swell. There are also unseen changes, however, that may cause noticeable symptoms. For example, when the hormone progesterone increases during pregnancy, it relaxes the body's smooth muscles. These muscles perform many functions, including the contracting of blood vessels. When you become pregnant, your rising progesterone levels cause your blood vessels to dilate, which can contribute to hemorrhoids and varicose veins, as well as cause a chronic stuffy nose or bleeding gums. You may also suffer from heartburn, since the muscle that controls the valve, or sphincter, between the stomach and esophagus relaxes, allowing acid to escape into the esophagus.

For every noticeable change, many more are not noticeable at all in a healthy pregnancy. Most major bodily organs, including the heart, lungs, and kidneys, have to work harder or differently in order to adapt to pregnancy. The bodies of most healthy women are able to adjust and adapt to these changes without difficulty. In some women with medical conditions, however, their disease may affect their body's ability to adapt to the demands of pregnancy.

Interestingly, some diseases may actually improve during pregnancy. Included in this category are certain immunological conditions, such as inflammatory bowel disease, asthma, and rheumatoid arthritis. The steroids your body produces when you're pregnant are similar to the treatment you'd ordinarily receive for these conditions. Bronwyn is a 23-year-old patient of mine who had asthma attacks that required visits to the emergency room nearly every month. During her pregnancy, however, because of the hormonal changes that occurred, her need for medication was reduced, and she had fewer attacks and emergency-room visits.

It ought to go without saying that the presence of two patients can also affect the treatment of any disease. Certain medications should not be used during pregnancy, since they can harm the developing fetus. Being pregnant may change the doses necessary to deal with an ongoing medical condition, or it may alter the effects of some treatments. Insulin requirements, for example, may change considerably during pregnancy, and cancer treatments are often severely restricted. In making decisions regarding treatment during pregnancy, doctors are often at a disadvantage. The amount of information regarding effects and treatment is limited, particularly since most major diseases aren't common in pregnant women.

Long before you conceive, consult with your doctor to see what you and she can do to make your pregnancy safe and your baby healthy. In rare cases, you'll discover that the risk to you or your fetus may be so great that pregnancy isn't advisable. Certain diseases of the heart and kidneys can become life-threatening during pregnancy, and life-saving treatments for cancer are sometimes impossible when you're pregnant. In these instances, unfortunately, abortion may have to be considered in order to safeguard your own life.

Medications used to treat a chronic condition such as arthritis or ulcers may need to be changed before pregnancy. In certain situations where the underlying disease itself may affect the baby's development, more careful control of the disease before conception may improve the chances of having a normal and healthy infant. Some of the questions you'll want to cover with your doctor are: How will your illness affect your pregnancy and prenatal care? Will you be able to stay active? Will you be able to continue to work? Will extra testing be necessary? Will your insurance pay for it?

Your care should involve a team of practitioners consisting of at least one medical doctor who is knowledgeable about illness in pregnancy and an obstetrician who is interested in and knowledgeable about medical conditions that complicate pregnancy. Depending on your illness, this may be accomplished by an internist and obstetrician in your community or may require a perinatologist or medical specialist at a university medical center.

It would take a whole textbook to cover all the possible diseases that can occur during pregnancy. In the following sections I will discuss some of the more common ones. Of particular importance here is that each patient and each medical condition varies, and medical information is always changing. Thus, it's crucial to check with your own doctor regarding your particular situation before you conceive.

A complex interaction between the heart and the blood vessels in your body maintains and controls your blood pressure. The heart pumps blood into your vascular system (blood vessels and arteries), and the small blood vessels control how quickly the blood returns to the heart. Your blood pressure is determined by the balance between the amount of blood going into the vascular system and the amount going out. A wide range of levels is considered normal for blood pressure, anywhere from about 90/60 to about 130/90 millimeters of mercury. The first number is the systolic blood pressure, referring to the maximum force caused by the heart's contraction, and the second number is the diastolic blood pressure, meaning the pressure during the relaxation phase between heartbeats. When your blood pressure rises above a certain point, it's considered abnormal and is called hypertension, or high blood pressure. The more elevated your blood pressure, the greater the risk to you and to your pregnancy. Low levels of elevated blood pressure can, in time, result in damage to the mother's heart, kidneys, and blood vessels. More severe elevations can lead to heart failure or even stroke.

During pregnancy, blood pressure levels normally decrease. In a pre-existing hypertension condition, however, your blood pressure may or may not decrease. High blood pressure during pregnancy increases your risk of developing pre-eclampsia (toxemia or pregnancy-induced hypertension), separation of the placenta (abruptio placenta), or placental insufficiency, in which the placenta doesn't supply enough oxygen and nutrients to the fetus, leading to an undergrown fetus or to fetal death.

Before trying to conceive, you should definitely seek medical counseling to discuss the severity of your hypertension and to evaluate its possible effects on your planned pregnancy. Your blood pressure should be brought under careful control, and medications you routinely take may need to be changed to those that will be safe during pregnancy. For example, a group of anti-hypertensives called ACE (angiotensin-converting enzyme) inhibitors can lead to fetal kidney dysfunction and stillbirth. Your doctor may advise testing of your kidney or heart function. In addition, you should make every effort to institute a healthy life-style as early as possible, including eating properly, controlling your weight, exercising, and avoiding alcohol and tobacco.

A pregnant woman with hypertension is considered to be at high risk. With current obstetrical practices, however, most patients with mild hypertension do quite well and have healthy infants. You'll need to make more frequent visits to the doctor, and you'll need to be tested for placental function and fetal growth by means of ultrasounds and non-stress tests, in which a monitor is placed on your abdomen to trace the baby's heartbeat. If your blood pressure rises, you may need to decrease your activity, which includes staying home from work. Your doctor may also prescribe medication. There is a chance that early delivery by inducing labor or by cesarean section will be necessary. If your hypertension is severe, you need to carefully examine the risks before attempting pregnancy.

Maria, 32, had mild hypertension, which was treated with a variety of drugs. When she came to me to plan her pregnancy, I changed her medication. Her blood pressure remained under control throughout most of her pregnancy, but I still monitored both her and her fetus carefully. At times, she wondered why I was so concerned, since she felt fine. At 37 weeks, tests revealed decreased amniotic fluid and a slowing of the fetal heartbeat, indicating a possibility of fetal distress. She was admitted to the hospital, and I attempted to induce labor. When her fetus's heartbeat further slowed, I performed a cesarean section. Luckily, both Maria and the baby turned out fine.

Don't be discouraged if you have hypertension. It's important, however, that you become aware of the risks, find out what steps you can take, and consult with your doctor to help you have the healthiest baby possible.

Diabetes mellitus is a chronic disease in which the body is unable to metabolize sugar properly, usually due to the pancreas' inability to produce enough insulin. The result is elevated levels of sugar in the blood and urine. Type 2 diabetes, the most common form, usually occurs later in adulthood and can often be controlled by diet alone or by oral medication. Type 1 diabetes, which often begins in childhood, is less common and more severe, requiring close monitoring of the diet and insulin injections to control blood sugar. Serious disease of the kidneys, eyes, heart, and blood vessels is more common with Type 1 diabetes, particularly when the disorder is not kept under complete control.

During pregnancy, the placenta produces several hormones that counteract the effects of insulin. The body must therefore produce more insulin -- as much as 30 percent more -- to do the required job. Under normal circumstances, the pancreas is easily able to keep up. In some women who are destined to become diabetic later in life, however, their bodies cannot meet the increased requirements of pregnancy, and they develop diabetes during pregnancy. Called gestational diabetes, this common disorder occurs in 1-3 percent of all pregnancies. These women are usually treated by diet and are monitored more carefully toward the end of pregnancy. Their outlook for having a healthy baby is excellent. After delivery, blood-sugar levels usually return to normal, but these women are at increased risk of developing diabetes later in life.

In women who are already diabetic, the control of blood sugar is made more difficult, because of the placental hormones and the nutritional needs of the fetus. Doctors once believed the conditions of women with kidney or eye disease as a result of diabetes worsened when they became pregnant. Now, the medical evidence suggests that pregnancy does not appear to have any long-term impact on such complications. In the rare woman who has heart disease associated with diabetes, the risk to her is so great that pregnancy is usually contraindicated.

You should be aware that birth defects are more common in diabetic pregnancies. In mild diabetics, the increased blood-sugar level crosses the placenta and raises the blood-sugar and insulin levels in the fetus, sometimes leading to very large babies. With large infants, the risk of trauma during birth is increased, as is the possible need for cesarean section. Blood sugar problems can also occur in the infants shortly after birth. For example, their pancreas may overreact and produce more insulin than necessary, causing low blood-sugar levels. In more severe diabetics, damage to blood vessels can lead to inadequate placental function, resulting in poor fetal growth and stillbirth.

Despite the risks, the outlook is encouraging. With the current level of understanding and medical management, many of the risks and complications of diabetes can be greatly reduced, making preconception evaluation and counseling extremely important. Most of the birth defects associated with diabetes -- typically involving the heart and the spinal canal -- happen in the first five to eight weeks of fetal development. There is reliable evidence that careful control of blood sugar before conceiving and during the early weeks of pregnancy can greatly reduce, but not eliminate, the risk of birth defects. Taking prenatal vitamins with folic acid before conception may also help. Much more careful control than usual of diet and blood sugar throughout the pregnancy -- checking glucose levels several times daily to ensure a normal level -- helps reduce the risk of birth defects, large infants, and metabolic problems after birth.

Careful monitoring of the fetus with non-stress tests and ultrasound may also be necessary, and early delivery by induction or cesarean section is sometimes required. Identification and early treatment of infections is also important, since diabetics are more susceptible. Urinary tract infections, for example, may be a possible cause of premature labor. A general medical examination that includes the eyes, kidney, heart, and blood pressure is often necessary to evaluate your current condition, assess risks, and plan for your pregnancy. Pregnancy in a diabetic is considered high risk and may require limitation of activity and possibly ceasing work and being hospitalized.

The management of a diabetic pregnancy is clearly a team effort that involves the patient, the obstetrician or perinatologist, and the internist or endocrinologist. The team may also include a nutritionist, ophthalmologist (eye specialist), nephrologist (kidney specialist), cardiologist (heart specialist), or neonatologist (newborn specialist). As always, a healthy life-style, including achieving proper weight, following a nutritious diet, exercising, and avoiding alcohol and tobacco will help to give you the healthiest pregnancy possible.

Heart disease comes in many forms, some more common than others. Some people are born with valve defects or holes in the heart, while others develop rheumatic heart disease and atherosclerotic heart disease. Surgery or medication is required for certain heart problems, but other conditions require no particular treatment. The effect on your life and your ability to carry a pregnancy depends on the type and severity of your heart disease.

The heart is responsible for pumping blood to all the organs of the body. The blood not only brings oxygen and nutrients to where they're needed but also removes carbon dioxide and waste products. Obviously, anything that interferes with this crucial process can significantly affect your health. During pregnancy the heart is called upon to work harder than usual, pumping as much as 50 percent more blood by the middle of pregnancy. The heart must work even harder during labor and delivery because of the physical exertion required. Then, when delivery has been completed, the vascular system undergoes many rapid changes, including blood loss and a rise in blood pressure, which in turn puts maximum stress on the heart.

The placenta is responsible for supplying the fetus with all the necessary oxygen and nutrients. If the heart does not work well, the placenta may not be able to fulfill its function. The result can be miscarriage, a malnourished fetus, premature labor, and even fetal death.

A healthy heart fulfills these extra demands easily, but a diseased heart may not be able to. Heart failure, heart attack, and even death have been known to result from stressing a weak heart during pregnancy and delivery, but the actual risk depends on the type and severity of the particular heart disease. Some conditions carry little or no increased risk during pregnancy, while others may require a change in the way they're treated or a limitation on activity. A few can be so risky to the mother that she will be advised to avoid pregnancy entirely.

In cases of mitral valve prolapse or certain abnormal heartbeats, or arrhythmias, pregnancy carries no increased risk and requires no special care. When Sarah, 29, first came to me, she was very worried. Her family doctor had diagnosed mitral valve prolapse, although she had no symptoms and felt fine. After confirming the details of the diagnosis with her other doctor, I was able to reassure her that she didn't need to worry. I placed her on antibiotics during her delivery to protect her heart from the possibility of infection, but this was all that was necessary.

In conditions such as pulmonary hypertension or Eisenmenger's syndrome, a rare congenital form of heart disease, the risk to your health is so great that pregnancy should not be considered, and effective birth control is essential. In still other types of disease, such as some forms of congenital or valvular heart disease, pregnancy may be possible, but it will require special monitoring and care to ensure a healthy mother and baby.

If you have a heart disease that is being treated by medication, you'll need an evaluation of the potential risk of your medication to a planned pregnancy. With some forms of heart disease, antibiotics are advised during dental work to protect the heart from infection. This assessment is even more important during pregnancy, and antibiotics will also be given during childbirth. To minimize the risk to you and your fetus, you may need to stop working, rest in bed, or even be hospitalized for some length of time prior to labor. There may also be a greater need for help with child care after the birth.

Lastly, since some forms of congenital heart disease may be inherited, genetic counseling is advisable to assess the risk of heart disease in your offspring. If there is any increased risk at all, it is usually small, but you may require special ultrasound studies early in the pregnancy and careful evaluation of your infant after birth.

Although heart disease and its effect on pregnancy must be taken seriously, in the absence of severe disease the outlook is quite good. As always, adhering to a healthy life-style is one positive step you can take, and this includes watching your weight, getting adequate rest, eating properly, and avoiding alcohol and tobacco. Exercise may or may not be advisable, depending on your particular situation.

Asthma is the most common respiratory problem in women of reproductive age, as well as the most common pulmonary complication of pregnancy. When you have asthma, the air-carrying tubes of your lungs are constricted by tightened muscles or mucous plugs, leading to shortness of breath, wheezing, and coughing. Although asthma is considered a chronic disease, acute attacks usually occur when you're exposed to allergens, chemicals, infections, or cold or dry air. The disease varies in severity and can usually be controlled by medication.

The effects of asthma on pregnancy vary. When you get pregnant, your asthma may improve, stay the same, or, for about a third of women, become worse. The more severe the disease before pregnancy, the more likely it will get worse, and if your asthma became worse in previous pregnancies, it's likely to worsen in future pregnancies as well.

An acute asthma attack can affect lung function, the amount of oxygen that gets into the blood, and uterine blood flow. Since adequate oxygen and uterine blood flow are necessary for normal fetal growth and development, theoretically the fetus can be harmed if an asthma attack reduces the oxygen content of the blood. For most women, however, if their asthma is controlled with medications during pregnancy, there appears to be no increased risk to the fetus.

If you suffer from asthma, preconception planning involves getting in the best physical shape possible. It's common sense to avoid anything that has caused an attack in the past. Although most asthma drugs can be safely taken during pregnancy, be sure your doctor reviews your particular medications with pregnancy in mind. Certain antibiotics commonly used for infections with asthma should be avoided, and certain over-the-counter asthma medications containing iodine can be harmful, since they may affect your fetus's thyroid. Steroids may be used in pregnancy if necessary, but if possible they should be taken by inhalation to reduce the dose to the fetus. Overall, the outlook for pregnancy for those with asthma is quite positive.

The urinary tract is made up of the kidneys, along with the ureters (the tubes that connect the kidneys to the bladder) and the urethra (the tube that leads from the bladder to the outside of the body). Kidneys serve several important functions, including the removal of waste products from the blood, control of fluid balance in the body, and the production of certain hormones that affect blood pressure and blood formation. Like the heart, the kidneys are required to work harder during pregnancy. A normal kidney can manage this easily, but diseased organs may not be able to respond to the increased demand. The hormonal and anatomic changes of pregnancy also cause the ureters to dilate, increasing the risk of kidney infection. Most important, there is some concern that pregnancy may permanently affect the progression of kidney disease, making it irreversibly worse than it might have been if pregnancy had not occurred. In rare cases the effect can be so severe that the pregnancy will have to be terminated to protect the life of the mother. If you have kidney disease, both the type and severity of the disease will determine what, if any, effect it will have on pregnancy, and vice versa.

In the past, doctors felt that the risk to mother and fetus was so great that pregnancy was rarely advised. More recent information tells us that the risks for many women with kidney disease is not as great as was once thought. Successful pregnancies are even possible for some women on dialysis or those who have undergone renal transplants.

Women with severe kidney disease may not be able to get pregnant, as they may not ovulate. This is not usually a problem in cases of mild disease. When pregnancy does occur, there are several potential hazards for both mild and severe cases. In as many as a third of women with kidney disease, blood pressure may rise and cause a risk for both mother and fetus. The risk of miscarriage, stillbirth, premature birth, or growth retardation increases. Still, in mild cases, the outlook for a healthy newborn is quite good.

Infections of the urinary tract are common and of particular concern during pregnancy. Bladder infections (cystitis) are quite common in women whether they are pregnant or not. Kidney infections (pyelonephritis) are less common but more serious. Some of the changes that occur during pregnancy, including dilation of the ureters and changes in the immune system, make it easier to develop urinary tract infections. Approximately 5 percent of women in general carry bacteria in their urinary tract without having signs of infection. This affliction is called asymptomatic bacteriuria. Left untreated, it is more likely to lead to kidney infection during pregnancy. Kidney infections are not only harmful to the mother but can also lead to premature labor and delivery.

If you have a history of kidney infections or frequent bladder infections, you should have a urine culture taken before pregnancy, and you may need to have several more done during pregnancy. In women without a previous history of urinary tract infections, urine cultures should be done at the first prenatal visit. Early detection and treatment of bacteria in the urine can prevent most cases of kidney infection in pregnancy.

Your preconception planning should include consultation with both a nephrologist (kidney specialist) who is sensitive to your desire to become pregnant and an obstetrician who is skilled in high-risk pregnancy. You will first be tested to determine the current status of your disease and your blood pressure. Following this, your doctors will give you the latest information regarding the risks to you and your planned pregnancy. More frequent visits to your doctors and more frequent testing of both you and your fetus will probably be necessary. Although risks exist, with current medical and obstetrical treatments the outlook for many women with kidney disease is good.

Thyroid diseases generally involve either an overactive or an underactive thyroid. An underactive thyroid produces too little of the hormone thyroxine, resulting in a slowing of your metabolism. Symptoms include lethargy, constipation, aching muscles, weight gain, a puffy face, and dry skin. On the other hand, an overactive thyroid produces too much thyroxin, which increases your metabolism, causing increased heart rate, sensitivity to heat, flushed skin, bulging eyes, weight loss, nervousness, and anxiety.

Pregnancy doesn't seem to affect most thyroid disease and, when it's properly treated and monitored, thyroid disease doesn't usually affect pregnancy. If untreated, however, a thyroid condition will usually interfere with ovulation, making it difficult to get pregnant or carry pregnancy to a safe conclusion.

For an underactive thyroid, it's vital that you take the proper amount of replacement hormone. Inadequate replacement can lead to infertility, miscarriage, or abnormal growth and development of the fetus. This is definitely not a medication to stop when pregnant or considering pregnancy.

Overactive thyroid disease can be treated during pregnancy but is better diagnosed and treated before conception. Radioactive agents used to treat or scan the thyroid, for example, should not be used during or shortly before pregnancy. If you are taking medications for a hyperactive thyroid, this may affect the fetus adversely, so you should check with your doctor. Some immunological types of thyroid disease, such as Graves' disease, may affect the fetal thyroid even after treatment in the mother has brought the disease under control.

When preparing for pregnancy, if you have any reason to suspect there might be something wrong with your thyroid, have it tested. Women with a history of thyroid disease should ask for a medical reevaluation with pregnancy in mind. With proper treatment, your outlook for a healthy pregnancy is excellent.

Cancer is a disease process in which a particular cell type grows out of control, often forming a tumor that may spread, or metastasize, to other parts of the body. Almost any cell in the body can become cancerous; more than 250 types of cancer have been identified. The chance of developing a particular type of cancer depends on many factors, both known and unknown, including sex, age, exposure to cancer-causing agents, and your family history. Pregnant women aren't more susceptible to cancer than nonpregnant women, but the cancers that pregnant women tend to develop are the ones most common in their age group, such as breast cancer, Hodgkin's disease, malignant melanoma, cervical cancer, and thyroid cancer.

The disease itself generally does not affect the fetus directly, since it's extremely rare for a tumor to metastasize to the placenta or fetus. However, any disease that can be fatal or cause severe illness can certainly affect the fetus indirectly. In these cases, pregnancy is rarely possible, since women who are severely ill tend to be infertile.

The tests necessary to diagnose cancer, such as those using X rays or isotopes (nuclear medicine scans), may affect the fetus. The precise effect depends on the amount of the exposure and the fetus's gestational age. The higher doses used in radiation therapy for treatment can certainly affect the fetus, potentially causing miscarriage, stillbirth, birth defects, or cancer later in life. Chemotherapy can also affect the fetus, depending on the particular drug used and the number of weeks into the pregnancy's progress. Surgery, the other common treatment for cancer, has the least hazardous effect on pregnancy.

In most cases, pregnancy does not appear to affect the behavior of the cancer itself. Some evidence shows that certain cancers may at times behave differently during pregnancy. Although malignant melanoma isn't caused by pregnancy hormones, it's believed that the hormonal changes of pregnancy may stimulate the melanoma's growth. In addition, rare cases have been reported where a melanoma has crossed the placenta and attacked the fetus. Breast cancer is harder to diagnose in pregnancy, and it may be diagnosed later because of the way pregnancy changes the breast (which is an excellent reason to have a pre-pregnancy breast exam). Stage for stage, however, survival rates are comparable whether you are pregnant or not. The treatment of most cancers in pregnant women is usually the same as those in nonpregnant women, except that the presence of the fetus must be taken into account. At times, this may mean terminating a pregnancy so therapy can begin, delaying treatment until the fetus is out of a vulnerable stage of development, delaying treatment until the fetus can be delivered early, or choosing a different diagnostic test or treatment that would least affect the fetus. The survival of the mother is normally the top priority, however.

Women who have or have had cancer should consult with their cancer specialist regarding the advisability of getting pregnant. With many curable cancers, having a baby is quite feasible after treatment, but a delay of several years may be advised, depending on the cancer and the type of treatment.

No special cancer-screening tests are necessary if you're planning to conceive, other than the routine ones already recommended for your age, including a Pap smear, pelvic examination, breast examination, and possibly a mammogram (if you're 35 or older). You should have these routine tests done before attempting pregnancy, not after. The evaluation of any abnormal findings can be complicated by the presence of a pregnancy even if no cancer is ultimately found. See your doctor immediately if you have any of the early warning signs, such as a change in your bowel or bladder habits, a sore that doesn't heal, unusual bleeding or discharge, an abnormal lump or growth in a breast or elsewhere, change in a wart or mole, difficulty swallowing, persistent hoarseness, or a nagging cough. Although most of the time these symptoms don't signal cancer, it pays to play it safe, both for you and your potential child.