Yellow, mushy bowel movements are perfectly normal for breast-fed babies. Still, there are many shades of normal when it comes to baby poop. Here's a color-by-color guide for newborns:

• Black or dark green. After birth, a baby's first bowel movements are black and tarry. This type of baby poop is known as meconium.
• Yellow-green. As the baby begins digesting breast milk, meconium is replaced with yellow-green bowel movements.
• Yellow. Breast-fed newborns usually have seedy, loose bowel movements that look like light mustard.
• Yellow or tan. If you feed your newborn formula, his or her bowel movements might become yellow or tan with hints of green. They will be slightly more firm than breast-fed bowel movements, but no firmer than peanut butter.

Once your baby begins eating solid food, his or her bowel movements might contain a wide variety of colors.

If you're concerned about the color or consistency of your baby's bowel movements, contact your baby's doctor. This is especially important if your baby's bowel movements are:

• Still black several days after birth
• Red or bloody
• White
• Suddenly more frequent and unusually watery
• Less frequent than what is normal for your baby or consistently hard, dry and difficult to pass

When you contact the doctor, be prepared to describe your baby's bowel movements, including color, consistency, volume and frequency. The more details you provide, the better the doctor will be able to help you determine what's normal for your baby — and when treatment might be needed.

Baby sign language — when babies use modified gestures from American Sign Language — can be an effective communication tool. Teaching and practicing baby sign language also can be fun and give you and your child an opportunity to bond.

Limited research suggests that baby sign language might give a typically developing child a way to communicate several months earlier than those who only use vocal communication. This might help ease frustration between ages 8 months and 2 years — when children begin to know what they want, need and feel but don't necessarily have the verbal skills to express themselves. Children who have developmental delays might benefit, too. Further research is needed, however, to determine if baby sign language promotes advanced language, literacy or cognition.

To begin teaching your child baby sign language, familiarize yourself with signs through books, websites or other sources. To get the most out of your baby sign language experience, keep these tips in mind:

• Set realistic expectations. Feel free to start signing with your child at any age — but remember that most children aren't able to communicate with baby sign language until about age 8 months.
• Keep signs simple. Start with signs to describe routine requests, activities and objects in your child's life — such as more, drink, eat, mother and father. Choose signs that are of most interest to your child. In addition to using formal signs, encourage meaningful gestures, such as pointing and the hand movements that accompany nursery rhymes.
• Make it interactive. Try holding your baby on your lap, with his or her back to your stomach. Embrace your baby's arms and hands to make signs. Use signs while communicating with your baby. To give signs context, try signing while bathing, diapering, feeding or reading to your baby.
• Stay patient. Don't get discouraged if your child uses signs incorrectly or doesn't start using them right away. The goal is improved communication and reduced frustration — not perfection. However, avoid accepting indiscriminate movements as signs.

Keep in mind that, as you teach baby sign language, it's important to continue talking to your child. Spoken communication is an important part of your child's speech development.

A baby sling — typically a one-shouldered baby carrier made of soft fabric — can be a safe way to carry a baby, if you follow safety guidelines. But a baby sling can pose a suffocation hazard to an infant, particularly those younger than age 4 months.

Babies have relatively weak neck muscles and can't control their heads during the first few months after birth. If the baby sling's fabric or your body presses against a baby's nose and mouth, the baby might not be able to breathe. This can quickly lead to suffocation. A baby sling can also keep a baby curled in a C shape, making it hard for a baby to breathe.

If you use a baby sling:

• Read the instructions. Double-check the baby sling's weight minimum before placing your baby in it.
• Keep your baby's airways unobstructed. Make sure your baby's face isn't covered by the baby sling or your body and is visible to you at all times.
• Take caution when bending. Bend at the knees, rather than at the waist, if you pick up something while holding your baby in a sling. This will help keep your baby settled securely in the sling.
• Be alert for wear and tear. Check for tears in the sling's seams and fasteners.

Sunscreen is OK to use on babies older than 6 months. Younger babies should use other forms of sun protection.

The best way to protect babies from the sun is to keep them in the shade as much as possible. In addition, dress your baby in protective clothing, a hat with a brim and sunglasses. Make sure he or she doesn't get overheated, however. You can also provide shade for your baby by using an umbrella or pop-up tent.

If your baby is older than 6 months, sunscreen is recommended. Pick a broad-spectrum sunscreen with an SPF of at least 30. Apply sunscreen generously to your baby's exposed skin, and reapply every two hours — or more often if your baby is spending time in the water.

To avoid irritating your baby's skin and eyes, use a sunscreen that contains zinc oxide or titanium dioxide.

A child's baby teeth (primary teeth) typically begin to loosen and fall out to make room for permanent teeth at about age 6. However, sometimes this can be delayed by as much as a year.

The first baby teeth to fall out are typically the two bottom front teeth (lower central incisors) and the two top front teeth (upper central incisors), followed by the lateral incisors, first molars, canines and second molars.

Baby teeth usually stay in place until they are pushed out by permanent teeth. If a child loses a baby tooth early as a result of tooth decay or an accident, a permanent tooth might drift into the empty space. This can crowd permanent teeth and cause them to come in crooked.

When your child starts to lose his or her baby teeth, reinforce the importance of proper dental care. For example:

• Remind your child to brush his or her teeth at least twice a day. Supervise and offer assistance as needed.
• Help your child clean between his or her teeth daily.
• Eat a healthy diet and limit between-meal snacks, especially those high in sugar.
• Schedule regular dental visits for your child.

With proper care, you can help your child's permanent teeth last a lifetime.

Baby walkers — devices designed to give babies mobility while they're learning to walk — can cause serious injuries. The American Academy of Pediatrics urges parents not to use baby walkers.

For example, babies who use baby walkers might:

• Trip and fall over
• Roll down stairs
• Get into dangerous places that would otherwise be difficult to reach

Research also suggests that use of baby walkers doesn't help the process of learning to walk. Instead, baby walkers eliminate the desire to walk.

Don't allow your baby to use a baby walker and make sure that your baby's other caregivers don't use baby walkers, either. Instead, consider using a stationary walker or activity center. Rather than wheels, these devices have seats that rotate and bounce. They will allow your baby to play safely as he or she learns to walk.

The short answer is no — there's not much the average couple can do to affect a baby's sex.

While old wives' tales suggest that a woman's diet or sexual position during conception can affect a baby's sex, these theories remain unproved. Likewise, researchers have found that timing sex in relation to ovulation — such as having sex days before ovulation to conceive a boy or closer to ovulation to conceive a girl — doesn't work.

Rarely, couples face the agonizing problem of knowing they could pass a genetic trait to a child of a specific sex — usually a boy. Under those special circumstances couples might use high-tech interventions to influence the chance of conceiving a girl. For example:

• Preimplantation genetic screening. With this technique — which is used in combination with in vitro fertilization — embryos are tested for specific genetic conditions and sex before they're placed in a woman's uterus.
• Sperm sorting. Various sperm-sorting techniques — which require artificial insemination or in vitro fertilization — can be used to reduce the likelihood of passing on a genetic condition, as well as select a child's sex.

These procedures are not recommended for choosing a baby's sex for nonmedical reasons. If you have concerns about passing on a genetic condition to your baby, talk to your health care provider.

"Back labor," a term used to describe intense lower back pain during and sometimes between labor contractions, does happen. It occurs when the baby's head puts pressure on your lower back.

To ease back pain during labor:

• Try massage. Ask your partner or labor coach to rub your lower back. Counter pressure against your lower back with a closed fist or tennis ball might help. Having one or two people provide pressure against your hips during contractions while you lean forward onto something might help, too. This is known as the double hip squeeze.
• Change positions. Straddle a chair and lean forward or kneel against a pile of pillows or a birthing ball. Take the pressure off your spine by getting on your hands and knees. To give your arms a break, lower your shoulders to the bed or a floor mat and place your head on a pillow. When you're lying down, lie on your side rather than on your back.
• Consider medication. Epidural and spinal anesthesia can temporarily block pain in your lower body. Although not widely used, some research suggests that shallow injections of sterile water to the lower back can provide temporary — but potentially significant — relief from back pain during labor.
• Hydrotherapy. Soaking in a tub or aiming the shower head at your lower back might provide relief.

Work with your health care team to evaluate your options for pain relief during labor. Whether you experience back labor or feel labor pain elsewhere, being familiar with pain management techniques can give you a greater sense of control.

If long periods seated at a desk are giving you a sore back, your office chair may need adjusting to give you better back support — or you may even need a new chair designed to reduce back pain. Sitting on a fitness ball for office work is not recommended.

To stay upright on a fitness ball, you have to make constant, small adjustments in muscle tension and weight distribution. This effort helps you achieve the benefits of core-strengthening exercises performed with a fitness ball. Prolonged balancing on a fitness ball during a full day of work, however, may lead to increased fatigue and discomfort in your back.

As you might think, bacterial infections are caused by bacteria, and viral infections are caused by viruses. Perhaps the most important distinction between bacteria and viruses is that antibiotic drugs usually kill bacteria, but they aren't effective against viruses.

Bacteria

Bacteria are single-celled microorganisms that thrive in many different types of environments. Some varieties live in extremes of cold or heat. Others make their home in people's intestines, where they help digest food. Most bacteria cause no harm to people, but there are exceptions.

Infections caused by bacteria include:

• Strep throat
• Tuberculosis
• Urinary tract infections

Inappropriate use of antibiotics has helped create bacterial diseases that are resistant to treatment with different types of antibiotic medications.

Viruses

Viruses are even smaller than bacteria and require living hosts — such as people, plants or animals — to multiply. Otherwise, they can't survive. When a virus enters your body, it invades some of your cells and takes over the cell machinery, redirecting it to produce the virus.

Diseases caused by viruses include:

• Chickenpox
• AIDS
• Common colds

In some cases, it may be difficult to determine whether a bacterium or a virus is causing your symptoms. Many ailments — such as pneumonia, meningitis and diarrhea — can be caused by either bacteria or viruses.