Whole-body vibration can offer some fitness and health benefits, but it's not clear if it's as good for you as regular exercise.

With whole-body vibration, you stand, sit or lie on a machine with a vibrating platform. As the machine vibrates, it transmits energy to your body, forcing your muscles to contract and relax dozens of times each second. The activity may cause you to feel as if you're exerting yourself.

You may find a whole-body vibration machine at a local gym, or you can buy one for home use.

Advocates say that as little as 15 minutes a day of whole-body vibration three times a week may aid weight loss, burn fat, improve flexibility, enhance blood flow, reduce muscle soreness after exercise, build strength and decrease the stress hormone cortisol.

But comprehensive research about whole-body vibration is lacking. It's not yet clear if whole-body vibration provides the same range of health benefits as exercise you actively engage in, such as walking, biking or swimming.

Some research does show that whole-body vibration may help improve muscle strength and that it may help with weight loss when you also cut back on calories.

Whole-body vibration may also have a role beyond sports and fitness. Some research shows that whole-body vibration, when performed correctly and under medical supervision when needed, can:

• Reduce back pain
• Improve strength and balance in older adults
• Reduce bone loss

Still, if you want to lose weight and improve fitness, enjoy a healthy diet and include physical activity in your daily routine. If you choose whole-body vibration, remember to do aerobic and strength training activities as well.

And because whole-body vibration can be harmful in some situations, check with your doctor before using it, especially if you're pregnant or have any health problems.

The short answer is no. Diet continues to be very important after bariatric surgery.

Because bariatric surgery changes the size of the stomach and, in some instances, the way the small intestine digests and absorbs food, you will lose weight. However, these changes also reduce your body's ability to absorb various nutrients. Short- and long-term nutrient deficiencies can develop.

Bariatric surgery also limits the types and amounts of foods and beverages you eat and drink. The quality of your diet is very important. You need to choose the right amounts and kinds of nutritious foods to stay healthy.

It's also possible to undermine your surgery with inappropriate high-calorie food and beverage choices that can slow weight loss — or even lead to weight gain.

It will be important to work with your doctor and a registered dietitian to learn how to eat in a new way to achieve and maintain weight loss, to treat and limit short- and long-term nutritional complications, and to feel your best.

Part of having a healthy pregnancy is focusing on your health before you conceive. Achieving a healthy pre-pregnancy weight can improve your chances of getting pregnant and minimize your risk of pregnancy complications.

Having a body mass index (BMI) of 30 and higher (obesity) can decrease your chances of having normal ovulation. Obesity can also affect the outcome of in vitro fertilization (IVF). As your BMI increases, so does the risk of unsuccessful IVF.

Obesity during pregnancy increases the risk of various pregnancy complications, including:

• The risk of miscarriage, stillbirth and recurrent miscarriage
• Gestational diabetes
• A pregnancy complication characterized by high blood pressure and signs of damage to another organ system, often the kidneys (preeclampsia)
• Cardiac dysfunction
• Sleep apnea
• A difficult vaginal delivery
• The need for a C-section and the risk of C-section complications, such as wound infections

In addition, your pre-pregnancy BMI will affect recommendations for weight gain during pregnancy. If you have a BMI of 25 to 29.9, your health care provider will recommend gaining 15 to 25 pounds (about 7 to 11 kg). If you have a BMI of 30 or more, your health care provider will recommend gaining 11 to 20 pounds (about 5 to 9 kg).

To lose weight before pregnancy:

• Schedule a preconception appointment
• Eat a healthy diet
• Consider talking to a registered dietitian or obesity specialist
• Get at least 150 minutes a week of moderate aerobic activity or 75 minutes a week of vigorous aerobic activity, or a combination of moderate and vigorous activity — preferably spread throughout the week

Efforts to develop a hepatitis C vaccine started more than 25 years ago, when the hepatitis C virus was identified. Since then, researchers have studied more than 20 potential vaccines in animals. A few of these vaccines, developed mainly in the past decade, have undergone limited testing in people.

The following two clinical trials are now underway to find out if recently developed experimental vaccines are safe and effective in people.

• Therapeutic vaccine trial. The study population in this trial consists of people who already have chronic hepatitis C. The purpose of the trial is to determine whether each vaccine is safe and successful at reducing evidence of hepatitis C in participants' blood. Completion of this trial is expected in 2020.
• Prophylactic (preventive) vaccine trial. This trial involves people at high risk of becoming infected with hepatitis C. Its purpose is to determine the safety of the two vaccines and find out whether participants receiving either vaccine are less likely to become infected with the hepatitis C virus over a six-month period than are participants receiving a placebo (inactive) vaccine. This trial has already enrolled a large sample of participants. It ends in July 2018.

If these trials have good results, larger trials will still be necessary to verify this effect and determine the best way to deploy the vaccine.

Progress has been slow for a number of reasons, including:

Unique characteristics of the virus

The hepatitis C virus is more variable than are the viruses that cause hepatitis A and hepatitis B. For starters, hepatitis C virus occurs in at least six genetically distinct forms (genotypes) with multiple subtypes. About 50 subtypes have been identified.

Different hepatitis C virus genotypes (variants) cause most infections in different parts of the world. A global vaccine would have to protect against all these variants of the virus.

Limited animal models of hepatitis C infection

Hepatitis C virus can infect chimpanzees, and the infection in chimpanzees is similar to that in human adults. Ethical and cost concerns, however, limit medical research with these animals.

If you're looking for an air purifier that will eliminate cigarette smoke, you're out of luck.

Tobacco smoke is made up of gaseous pollutants and particulate matter. Most air purifiers, also called air cleaners, aren't designed to remove gaseous pollutants.

Mechanical air filters, such as high-efficiency particulate air (HEPA) filters, and electronic air cleaners, such as ionizers, target particles. While air cleaning devices can help reduce levels of smaller airborne particles, research suggests that the devices aren't 100 percent effective. This might be due to the difficulty of cleaning particles from every room in a home, and the fact that many particles from secondhand smoke are on the surfaces of furniture and clothing. When someone touches these surfaces, the particles become airborne again and are breathed in before they can be filtered. Air cleaners also might not decrease harmful health effects caused by indoor pollutants such as cigarette smoke.

Other air cleaners generate ozone, which is a lung irritant. At levels that don't exceed public health standards, ozone has little ability to remove air contaminants such as cigarette smoke.

The best way to protect nonsmokers from secondhand smoke is to not allow smoking in your home. If you smoke, this is another good reason to stop.

Asthma symptoms that start in childhood can disappear later in life. Sometimes, however, a child's asthma goes away temporarily, only to return a few years later. But other children with asthma — particularly those with severe asthma — never outgrow it.

In young children, it can be hard to tell whether signs and symptoms such as coughing, wheezing and shortness of breath are caused by asthma or something else. Sometimes, what seems to be asthma turns out to be another condition, such as bronchitis, recurrent pneumonia or bronchiolitis. These and a number of other asthma-like conditions typically improve as children get older.

Children with more-severe asthma are less likely to outgrow it. Persistent wheezing and a history of allergies, especially to furry animals, also increase the odds that your child won't outgrow asthma.

It's important to diagnose and treat childhood asthma early on. Work with your child's doctor to manage your child's asthma. A written asthma action plan can help you track symptoms and adjust medications and help your child avoid asthma triggers. As your child gets older, involve him or her in the development of the action plan.

No, Wilson's syndrome, also referred to as Wilson's temperature syndrome, isn't an accepted diagnosis. Rather, Wilson's syndrome is a label applied to a collection of nonspecific symptoms in people whose thyroid hormone levels are normal.

Proponents of Wilson's syndrome believe it to be a mild form of thyroid hormone deficiency (hypothyroidism) that responds to treatment with a preparation of a thyroid hormone called triiodothyronine (T-3). However, the American Thyroid Association has found no scientific evidence supporting the existence of Wilson's syndrome.

In a public health statement, the American Thyroid Association concluded:

• The diagnostic criteria for Wilson's syndrome — low body temperature and nonspecific signs and symptoms, such as fatigue, irritability, hair loss, insomnia, headaches and weight gain — are imprecise.
• There's no scientific evidence that T-3 performs better than placebo in people with nonspecific symptoms, such as those described in Wilson's syndrome.

Hypothyroidism can be diagnosed by blood tests that detect insufficient levels of thyroid hormone. Wilson's syndrome shouldn't be confused with Wilson's disease — a rare, inherited disorder that causes too much copper to accumulate in certain organs.

Although it's frustrating to have persistent symptoms your doctor can't readily explain, it could be worse to accept an unrecognized diagnosis from an unqualified practitioner. Unproven therapies for so-called Wilson's syndrome may leave you feeling sicker, while a treatable condition — such as fibromyalgia or depression — goes undiagnosed.

Wisdom teeth — the third molars in the very back of your mouth — may not need to be removed if they are:

• Healthy
• Grown in completely (fully erupted)
• Positioned correctly and biting properly with their opposing teeth
• Able to be cleaned as part of daily hygiene practices

Many times, however, wisdom teeth don't have room to grow properly and can cause problems. Erupting wisdom teeth can grow at various angles in the jaw, sometimes even horizontally. Problems can include wisdom teeth that:

• Remain completely hidden within the gums. If they aren't able to emerge normally, wisdom teeth become trapped (impacted) within your jaw. Sometimes this can result in infection or can cause a cyst that can damage other teeth roots or bone support.
• Emerge partially through the gums. Because this area is hard to see and clean, wisdom teeth that partially emerge create a passageway that can become a magnet for bacteria that cause gum disease and oral infection.
• Crowd nearby teeth. If wisdom teeth don't have enough room to come in properly, they may crowd or damage nearby teeth.

Some dentists recommend removing wisdom teeth if they don't fully emerge. Many dentists believe it's better to remove wisdom teeth at a younger age, before the roots and bone are fully formed, and when recovery is generally faster after surgery. This is why some young adults have their wisdom teeth pulled before the teeth cause problems.

According to the American Dental Association, wisdom teeth removal may be necessary if you experience changes in the area of those teeth, such as:

• Pain
• Repeated infection of soft tissue behind the lower last tooth
• Fluid-filled sacs (cysts)
• Tumors
• Damage to nearby teeth
• Gum disease
• Extensive tooth decay

The decision to remove wisdom teeth isn't always clear. Talk to your dentist or an oral surgeon about the position and health of your wisdom teeth and what's best for your situation.

Some wrist blood pressure monitors may be accurate if used exactly as directed. However, the American Heart Association recommends using a home blood pressure monitor that measures blood pressure in your upper arm and not using wrist or finger blood pressure monitors.

Wrist blood pressure monitors are extremely sensitive to body position. To get an accurate reading when taking your blood pressure with a wrist monitor, your arm and wrist must be at heart level. Even then, blood pressure measurements taken at the wrist are usually higher and less accurate than those taken at your upper arm. That's because the wrist arteries are narrower and not as deep under your skin as those of the upper arm.

Some people can't have their blood pressure measured at the upper arm because they have a very large arm or find blood pressure measurements painful. In these cases, measuring blood pressure at the wrist is acceptable.

It's common for blood pressure readings taken at home on any type of monitor to be different from those taken at your doctor's office. If you have a wrist blood pressure monitor, it's a good idea to take your monitor to a doctor's appointment. Your doctor can then check your blood pressure with both a standard upper arm monitor and a wrist monitor in the correct position in the same arm to check your wrist blood pressure monitor's accuracy. Also make sure to use a validated device.

The possibility of an X-ray during pregnancy causing harm to your unborn child is very small. Generally, the benefits of the diagnostic information from an X-ray outweigh the potential risk to a baby. However, if you received a large number of abdominal X-rays over a short period before you were aware of your pregnancy, your baby could be affected.

Most X-ray exams — including those of the legs, head, teeth or chest — won't expose your reproductive organs to the direct X-ray beam, and a lead apron can be worn to provide protection from radiation scatter.

The exception is abdominal X-rays, which expose your belly — and your baby — to the direct X-ray beam. The risk of harm to your baby depends on your baby's gestational age and the amount of radiation exposure. Exposure to extremely high-dose radiation in the first two weeks after conception might result in a miscarriage. However, these dose levels aren't used in diagnostic imaging.

Exposure to high-dose radiation two to eight weeks after conception might increase the risk of fetal growth restriction or birth defects. Exposure between weeks 8 and 16 might increase the risk of a learning or intellectual disability. But the typical dose of a single radiation exposure associated with a diagnostic X-ray is much lower than the high dose associated with these complications.

Before having an X-ray, tell your doctor if you are or might be pregnant. Depending on the circumstances, it might be possible to postpone the X-ray or modify it to reduce the amount of radiation. In addition, if you have a child who needs an X-ray, don't hold your child during the exam if you are or might be pregnant.

If you had a diagnostic X-ray before you knew you were pregnant, talk to your health care provider.