During infancy – from birth to age 12 months – babies experience rapid physical growth and development. Their weight usually doubles by 5 or 6 months of age and triples by their first birthday. An infant’s nervous system – brain, spinal cord and nerves – also develops, allowing them better control of the head and limbs, which enables them to explore their new environment and interact with others.

Generally, healthy babies reach certain developmental milestones by the first year. These can include, but are not limited to:

• Rolling over by themselves
• Sitting alone, without support
• Crawling
• Making babbling or squealing sounds
• Standing up
• Walking, while holding on to furniture or a person for support
• Saying at least one word, usually “mama” or “dada”

Although most babies reach these milestones at similar stages, infancy development can differ and it is normal for healthy babies to grow and develop at their own pace. However, parents should notify their child’s physician if their baby displays signs of possible developmental delays during infancy. These include failure to thrive, not being able to crawl or stand when supported, not trying to imitate words and not using gestures like waving hands or pointing to objects.

To support adequate growth and development during infancy, proper nutrition is essential. Another important step is ensuring that infants get regular check-ups with a physician, preferably a pediatrician. During these well-child visits, the pediatrician can ask the parents if the infant has met certain milestones for each stage of development.

Babies can grow with an environment rich in stimulation, comfort and loving attention. Other ways parents and caregivers can promote healthy infancy development include:

• Encouraging bonding by cuddling, holding, rocking and caressing the baby to help newborns feel safe, secure and loved.
  
  
• Supporting age-appropriate physical activity. Give babies space to stretch, explore and crawl or walk around the home. However, do not leave them unattended and make sure the home is childproof.
  
  
• Stimulating learning and play. Provide babies with safe, age-appropriate toys with different textures that encourage them to explore with the fingers. Singing, reciting rhymes and doing finger plays with a baby can also stimulate their cognitive development.
  
  
• Nurture language development. Talk and read often to a baby, in addition to naming objects while pointing to pictures in a book. Use simple words that apply to an infant’s everyday life.

Infancy is the developmental stage occurring from birth to 12 months during which babies experience rapid changes, including physical growth and brain development. Most newborn babies double their birth weight by the time they are 5 or 6 months old and triple it by their first birthday. An infant’s nervous system – brain, spinal cord and nerves – matures, allowing them better control of the head and limbs, and also enabling them to grasp objects and crawl by their first birthday.

Other milestones healthy infants typically accomplish by their first year include the use of simple gestures like shaking their head and trying to imitate words by making babbling sounds. Although most babies reach certain milestones at similar stages, infancy development can differ. Healthy babies grow and develop at their own pace. Babies who were born prematurely may lag slightly. If they were born a month prematurely, they may reach any given milestone a month later than a full-term baby.

Much intense development occurs during pregnancy, but equally important growth occurs in the first year. The baby begins to breathe at birth, developing the respiratory system. The cardiac system has functioned during prenatal development, but after birth changes occur in the heart so blood is oxygenated and transported throughout the body. The baby begins to feed through the mouth and clears wastes through its own digestive system. The brain and nervous system develop control of body functions and sleep and wake cycles.

In addition to physical development of organs, babies have huge developmental changes in their motor skills, cognitive abilities and psychosocial connections during the first year of life. In each area, there is a wide range of normal development.

Nonetheless, parents should notify their child’s physician if their baby displays signs of possible developmental delays during infancy. These include failure to thrive, not being able to crawl or stand when supported, not searching for objects that are hidden from view, not trying to imitate words or not using gestures such as waving hands or pointing to objects. Possible causes of developmental delays in infants include premature birth, congenital conditions (e.g., fetal alcohol syndrome), mental retardation or lack of adequate nutrition.

To promote infant health and development, pregnant women should receive prenatal care. Research suggests that women who see an obstetrician-gynecologist – a physician who specializes in the female reproductive system and childbirth – regularly during pregnancy have healthier babies, are less likely to deliver prematurely, and are less likely to have other serious problems related to pregnancy.

Another crucial step in promoting healthy infancy development is ensuring that infants get regular check-ups with a physician, preferably a pediatrician. The American Academy of Pediatrics (AAP) recommends well-child visits immediately after birth, then two to four days later, or before going home from the hospital. After that, parents should take their infants for well-child visits at 1, 2, 4, 6, 9 and 12 months of age.

The birth of a baby can be a source of great joy for the entire family. However, because it is a life-changing experience it can be very stressful as parents and other family members adjust to the new addition. Parents can better their chances of adjusting by learning about infancy and healthy development prior to their baby’s birth.

Expecting parents can find information on infancy development on the Internet and in the numerous books available on the subject. Many school districts, hospitals, mental health facilities and community centers offer courses for first-time parents. A physician or mental health professional, such as a licensed family therapist, may be able to provide referrals for parenting courses.

During the first year of life, infants experience rapid physical growth. Most babies triple their birth weight and increase in length by as much as 50 percent by their first birthday. A newborn’s brain is only about 25 percent of its approximate adult size. The brain will continue to grow and develop throughout childhood and reach its peak sometime during adolescence – around age 15.

Most healthy newborns are born weighing anywhere from 6 pounds, 2 ounces (2,812 grams) to 9 pounds, 2 ounces (4,173 grams). On average, a newborn’s length typically ranges from 19 to 21 inches (48.3 to 53.3 centimeters). Many factors can affect a newborn’s size at birth including length of pregnancy, multiple births and/or birth order, gender and health in addition to the mother’s health and nutrition during pregnancy.

During the first week of life, a newborn’s weight may decrease as much as 10 percent below initial birth weight. Generally, this is common and should not be cause for concern. This weight loss is usually related to the normal fluid loss after birth and the infant’s ability to feed. This ability improves gradually and by the second week of life, most babies regain or exceed their initial birth weight.

A newborn’s skull is flexible and consists of several bones that will gradually fuse together over time. It includes two soft spots called fontanels where cranial bones have not yet fused. This flexibility allows the head to squeeze through the narrow birth canal and can give infants born vaginally a cone shaped head. The flexibility of the fontanels also accommodates a baby’s rapidly growing brain during the first 12 to 18 months of life.

This flexibility early in life can make an infant susceptible to developing flat spots on the head (positional plagiocephaly). This condition is not serious and may be treated by changing a baby’s head position regularly or with the use of special headbands or molded helmets. A newborn’s head may also have lumps or bruises as a result of the trauma of delivery. This is normal and often lessens over a few days or weeks. 

In addition to the head, other features such as the face, ears, nose or jaw, may be distorted by the position they were in before birth. As the trauma of delivery subsides, an infant’s features typically change significantly. The white part of a newborn’s eyes may appear bloodshot initially. This condition, called subconjunctival hemorrhage, is also caused by the trauma of delivery and typically disappears without medical treatment after several days.

The genitals (sex organs) of both male and female newborns may be swollen at birth. This often subsides on its own as a baby grows. However, in some cases it may be caused by an inguinal hernia – a condition in which part of the intestines juts out through a weak spot in the groin (where the abdomen meets the thigh). An inguinal hernia usually requires surgical treatment.

In most cases, a newborn’s eye color will change overtime. Most babies are born with bluish-gray eyes that gradually lighten or darken as pigmentation of the iris (color part of the eye) takes on a permanent color around age 3 to 6 months. However, babies born with brown eyes do not experience a change of eye color.

A newborn’s skin also undergoes change. Most healthy babies typically have deep red or purple skin and bluish hands and feet at birth. The skin usually lightens a little in the next couple of days and may become initially dry or flaky. Maternal hormones can cause mild skin rashes that resemble acne on babies, which usually clear on their own in a few weeks.

Newborn skin is sensitive and it is not usually recommended to give newborns a tub bath until the umbilical cord stump has fallen off. This typically occurs by the time a baby is 8 weeks old. A sponge bath or damp washcloth – using mild baby soap applied to the water if needed – is the best way to clean a newborn until the cord stump falls off. Also, baths in a tub or sink should be deferred until the circumcision site (in boys) is completely healed. A bath two to three times a week during a baby’s first year of life is all that is needed to maintain hygiene. More frequent bathing is discouraged since it may dry an infant’s delicate skin.

Parents and other caregivers also should keep the infant’s umbilical cord stump as clean and dry as possible. If the area becomes wet or soggy during a sponge bath, it should be gently dried. Parents are urged to consult with their baby’s doctor if the navel area becomes reddened or starts to bleed or if a foul odor or discharge develops as these can be signs of infection.    

Jaundice in healthy newborns is common and often appears around the second or third day after birth and may disappear without treatment within one to two weeks. This is caused by excess bilirubin (a waste product) that accumulates in the body because a baby’s undeveloped liver is not able to remove it effectively at first.

Pediatric health experts generally recommend that infants gain at least 2 pounds (907 grams) by their third month to support healthy growth and development. During the first three months, babies can grow in length by as much as 1.4 inches (3.5 cm) per month and their head size can increase in circumference by 0.79 inch (2 cm) per month. Throughout the baby’s first year, the pediatrician will monitor growth in weight, height and head size for any abnormalities.

Sometime between the fifth and eighth months, an infant’s first tooth usually appears. The two bottom front teeth are normally the first to appear. By the end of the first year, babies typically have six to eight teeth. Signs indicating an infant is teething include excessive drooling, swollen gums, irritability, trouble sleeping and a low-grade fever. Dental care is important even before an infant starts teething. After feedings, parents are urged to gently run a damp washcloth over a baby’s gums to keep bacteria from building up. When teeth begin to appear, a small, soft-bristled toothbrush can be used. 

During the first six months of infancy, proper nutrition can be limited to breast milk or formula. After that, a combination of solid foods – starting with iron-fortified baby cereals at first – and either breast milk or formula should be given until a baby is 1 year old.

Babies are born with several involuntary muscular responses to sensory stimuli, such as light or touch, which gradually disappear as a baby’s nervous system – brain, spinal cord and sensory nerves – develops. These are called primitive reflexes and include the following:

• Rooting and sucking reflex. It triggers newborns to turn their heads when their cheeks are touched (in search of food) and begin to suck on a pacifier, baby bottle or any object placed in their mouths.
  
  
• Tonic neck response reflex. This prompts an infant to extend the left leg when looking to the left, while the right arm and leg flex inward, and vice versa.
  
  
• Grasp reflex. It causes a baby to tightly close the fingers when pressure is applied to the inside of the hand by a finger or other object.
  
  
• Moro reflex. Also called startle response. It prompts an infant to suddenly throw the arms out to the sides and then quickly bring them back towards the body when startled by a loud noise or other stimulus.
  
  
• Stepping and walking reflex. When a supported infant’s feet are placed on a hard surface, the baby makes stepping motions.

Most primitive reflexes disappear in the child’s first few months. Primitive reflexes that persist beyond a certain age may be a sign of developmental delays or central nervous system problems. Infants are also born with a number of reflexes that continue throughout life, such as blinking, sneezing, coughing, yawning and gagging.

For a few weeks after birth, newborns continue to use the fetal position – fists clenched, elbows bent, hips and knees flexed, and arms and legs held close to the front of the body. A baby’s arms, legs and chin may tremble or shake, especially when the baby is crying or agitated. As the nervous system matures, this response lessens.

During the first two months of life, infants typically display limited movement of their extremities – mainly writhing and simultaneous opening and closing their hands. Between the first and second month, babies can usually lift and turn their heads when lying on their backs. However, a baby’s neck muscles cannot yet support the head. Any person holding a young infant must support the baby’s neck and head. It is also important to never shake a baby. Shaking a baby can cause a serious and sometimes fatal condition called shaken baby syndrome, which may damage the brain and delay normal development.

From about age 3 to 4 months, most of a baby’s primitive reflexes have disappeared or are beginning to do so. Infants can now roll from their backs to one side and can better control hand and feet movement, although they are still unable to coordinate grasp. Babies can grasp and shake toys that are placed in their hands, but cannot pick them up if dropped. They also typically attempt to grab dangling toys or other objects. At this age, babies begin to put objects into their mouths.

Many 3 and 4 month-old infants are able to raise their heads and upper bodies with their arms while lying on their stomachs. Around this time, babies can keep their heads up while sitting up (with support) because neck muscles are more developed.

From age 5 and 6 months, infants can grab larger objects like blocks and cubes, as well as pick them up if dropped. However, they have not yet achieved fine motor control of the thumb and index finger for grabbing. Many infants this age may be able to hold their own bottles, but only for short periods of time. Most babies can now completely roll over from the back to the stomach.

While lying on the stomach, 5- and 6-month old babies can push up with their arms to lift up the shoulders and head and look around or reach for objects. Around this stage, most babies are also able to sit alone without support for brief periods. Infants also typically display what is called a parachute reflex to protect against falling. This involuntary muscle response can be elicited by holding a baby upright then rotating its body quickly face forward, as if falling. The baby’s arms instinctively extend as if to break a fall.

From months 6 to 9, infants are typically able to sit steadily for long periods of time, especially when placed in a high chair. Most healthy babies are learning to crawl and may be able to pull themselves up – and remain standing – while holding onto large objects, especially furniture. Many infants are able to sit from a standing position with assistance. At this stage, most babies are also able to walk while holding the hands of an adult.

From months 9 to 12, babies often begin displaying a preference for the dominant hand when grabbing toys or other objects. They have better coordination of the thumb and index finger, which allows for a pincer grasp – grabbing small objects between the tips of these fingers. Most babies can also turn through the pages of a book by flipping many at a time and are generally able to finger feed themselves.  

Generally, older infants begin to balance better while standing without support and can also sit down unassisted. Most healthy babies usually begin taking steps or may even start walking without help by their first birthday.

Most newborns are alert for the first 40 minutes following birth, and are often ready to interact and eat if given the opportunity. However, a newborn’s initial level of alertness can be affected by any medications administered to the mother during childbirth and fetal hypoxia (low oxygen levels in the fetus) due to labor complications.

This initial period of alertness may be the longest stretch of time babies are awake and alert for their first few days. Many healthy infants sleep 16 hours or more a day. Sleep and wake cycles are extremely variable at first and generally do not stabilize until a baby is 3 months old.

Crying is a newborn’s main way of communicating, especially urgent needs like hunger. Other common causes of crying include gas pain, colic, discomfort (e.g., wet diaper) or when the baby is overwhelmed by the sounds and sights of the environment. They may also cry for no apparent reason.

Parents or other caregivers should respond in a timely manner to a newborn’s cries. Holding infants close to the chest often soothes their cries. However, prolonged crying may be a sign of an illness and in such cases a pediatrician should be contacted.

Research suggests that infants as young as a few days old prefer human stimuli best, especially the faces, voices, touch and even smell of their parents. Second to people, newborns like to look at bright lights or objects and anything that moves. Newborns can see objects within a range of 8 to 14 inches (20 to 35 centimeters). They can also see objects that are farther away, but it is harder to focus on them. Despite this initial limited range of vision, a light shining from a distance may still catch a newborn’s eyes.

Healthy newborns can see contrasting colors better than similar ones. For instance, black-and-white objects will usually captivate a baby’s attention longer than those with similar colors. Babies may appear cross-eyed for brief periods during the first four months because a newborn’s eye muscles are still developing. Parents should contact a physician, preferably an ophthalmologist, if a baby’s eyes seem to cross more than just briefly and if the condition persists for longer than 4 months. An infant should also be taken for an eye exam if the eyes appear cloudy or filmy, or seem to wander in circles when trying to focus on objects.

The rest of the senses – hearing, smell, touch and taste – are generally well developed in healthy infants at birth. By the second week of life, newborns can better focus their eyesight and most can recognize their mother’s voice. This is typically demonstrated by a tendency to turn towards the mother at the sound of her voice. Newborns usually respond to the smell and touch of their mothers, as well as the level of responsiveness to basic needs like hunger.

By age 2 months, most babies can smile on purpose, blow bubbles and coo when being held or when a parent or caregiver talks gently. They also begin to anticipate events, especially feeding time. Infants commonly start sucking at the sight of a baby bottle or a mother’s breast.

From age 3 months on, babies typically begin to show more interest in their immediate surroundings. Enhanced eye muscle control allows babies to track moving objects. They can also distinguish objects from backgrounds with little or no contrast, such as the buttons on a shirt of the same color.

During feedings, infants may no longer be content to just look at the person feeding them and can become easily distracted by other interesting sights or sounds. They can recognize faces and distinguish people by how they look, sound or feel. They also generally react to and attempt to imitate the facial expressions of others.

Around age 4 to 6 months, most babies usually start attempting to communicate by making babbling, squealing, gurgling and even laughing sounds. Babies may even be able to recognize their names now. Infants can learn from every interaction, especially through play.

Caregiving activities such as feeding, bathing and diapering provide adults with plenty of opportunities for gentle playing to support a baby’s cognitive (intellectual) development throughout infancy. Parents and caregivers are encouraged to talk, sing, recite rhymes and do finger plays often with their infants.  

Babies at this stage also prefer to face outward while being held and often wiggle their bodies around so that they can have a better view of their surroundings. They also display more curiosity about themselves and usually explore their bodies by staring at their hands, touching their ears, cheeks or any other part of their body within reach.

From months 6 to 12, infants explore their world by touching and putting objects and toys into the mouth. As they progress through infancy, a budding curiosity and urge to experiment prompts them to use objects. Babies will pick up and inspect items, often by passing them from hand to hand, banging, dropping or throwing them. They will also put anything in their mouths at this stage.

Infant education experts generally recommend reading to babies beginning at age 7 months or younger. Reading and talking to infants helps develop their speech and thought. 

Large, bright picture books can engage infants and eventually they will connect the words heard with the pictures.

A major cognitive developmental milestone that occurs at around 9 months of age is the ability to recognize that objects exist even when they are out of sight (object constancy). Babies can exercise their growing cognitive skills by searching for objects (e.g., toys) that are hidden while they are looking. They usually express great delight, often by squealing, when these items are found. Although older infants may look for hidden objects, they are still unable to consider alternative locations.

Older infants can usually distinguish emotions by a person’s tone of voice, and are also able to locate sounds by turning their head. They generally attempt to repeat sounds they hear too, especially speech and animal sounds. Older babies can also associate the names of objects and are generally able to look at a correct picture when an image is named.

Many infants at this stage understand the meaning of some words, especially “no,” and other simple commands such as “come here.” They usually use simple gestures like shaking their head for “no” and waving their hands for “bye-bye.” Most babies can probably say “mama” and “dada” – and use these terms appropriately – and perhaps a couple more words by their first birthday.

Psychosocial development in infancy includes babies learning to interact with the world and people around them. Bonding is an essential component of healthy emotional and social development. Most healthy infants are ready to bond immediately after birth. Pediatric health experts recommend that parents feed and hold a newborn to initiate bonding right away. Parents should not be concerned if immediate bonding is not possible (e.g., premature birth or adopted infants).

Parents typically bond with their infant by touching gently and speaking to the baby frequently and in numerous other ways including during feeding, bathing and other caregiving activities. Providing babies with an environment rich in stimulation, comfort and loving attention bolsters healthy infancy development. Studies also show that babies who are spoken to and read to and otherwise engaged in plenty of verbal interaction by parents or other caregivers show more advanced language skills than infants who are not.

Crying is a newborn’s initial means of communicating. Parents and caregivers quickly learn to differentiate between an infant’s cries of hunger, pain and discomfort. Gradually, babies learn to communicate in other ways. For instance, a newborn’s face will brighten when they are cuddled or hear a soothing voice. Even when they are a few days old, a newborn may try to imitate a person sticking out his or her tongue.

Newborns usually smile when they are sleeping. However, at this time it is an involuntary reaction rather than an emotional response. By 2 or 3 months of age, a baby’s smile is a genuine expression of affection or pleasure. Soon, the baby will start reaching for a parent or other primary caregiver for attention or comfort.

By 3 months of age, healthy infants typically enjoy playing with others, especially their parents or caregivers. They may also cry when playing stops. Playing is an important way of stimulating a baby’s cognitive development and also how they learn to interact with others. At this stage, babies are more communicative and expressive with their faces and bodies. They typically try to imitate some movements and facial expressions.

By 7 months of age, many babies become shy or anxious with strangers. They may not want to stay with anyone other than their parents or primary caregivers and may even turn away from grandparents or other family members.

By 9 months of age, most infants are afraid of being left alone. They also usually experience separation anxiety and often show this by being clingy with parents and crying when parents leave. However, some older infants – especially those who can walk – may make brief exploratory journeys away from parents in familiar settings.

By the end of the first year, many babies develop an attachment to a favorite toy or object, such as a blanket. They also typically show specific preference for certain people, such as a familiar babysitter.

One-year-olds generally begin testing their parents with their behavior. This is a normal, healthy part of an infant’s emotional and social development. They are learning about how the parent will respond to behaviors, such as refusing to eat when being fed or crying when a parent leaves a room. It is important for parents to respond with patience because a loving, consistent and understanding attitude will help a baby develop confidence and a sense of security.

Throughout infancy, babies depend entirely on their parents and caregivers for basic needs as they begin to gradually explore their new environment. Almost any interaction with a baby can provide parents with opportunities for encouraging their infant’s growth and development. Showing them plenty of attention, basic care and love are the cornerstones for promoting healthy infancy development.  

Safety is another important component of infant health and development. Newborns and babies up to 5 months old should always be put to sleep on their back to reduce risk of sudden infant death syndrome (SIDS). Parents and other caregivers should use a firm mattress and avoid placing fluffy blankets, stuffed animals, pillows or any material in an infant’s crib that can cause smothering.

Vehicle safety should be enforced at all times, even when traveling short distances. Babies should always be strapped into a rear-facing or convertible car safety seat placed in the back seat of a vehicle before driving.

Infants should never be left unattended – even for short periods – or with young siblings or pets, especially on surfaces (e.g., bed, changing table) where they may wiggle or roll over and fall, or in or near water (e.g., bathtub). Older infants who can crawl or walk are at increased risk for accidents and injuries. Therefore, potentially dangerous areas of a home, such as the windows, stairs and kitchen entrances should be blocked off by using special gates or guards. Any household rooms that are not childproof should be kept locked at all times. Preferably, parents should childproof a home prior to their baby’s birth.

To prevent poisoning, all household cleaners, chemicals and medicines should be stored out of an infant’s reach. Furniture with sharp edges should be removed or soft guards should be put on these to prevent injuries. Small objects (e.g., coins, safety pins, toys) or plastic bags also should be kept out of a baby’s reach to prevent choking. One should never carry hot liquids or foods when holding a baby, and dangerous appliances (e.g., irons) need to be kept out of their reach.

All households with infants should have a well-stocked first-aid kit as well as a list of important phone numbers (e.g., Poison Control Centers, neighborhood hospitals). Parents and caregivers may also learn to perform cardiopulmonary resuscitation (CPR) on infants by taking special classes.

Other ways parents and other caregivers can promote healthy infancy development include:

• Encourage bonding. Spend time cuddling, holding, rocking, caressing and kissing a baby. This will help newborns feel safe, secure and loved.
  
  
• Support age-appropriate physical activity. For instance, give newborns enough space so that they are able to stretch and move their arms and legs. These movements can help them strengthen and tone muscles. It is also important to let newborns turn and lift their heads by changing their positions regularly.
  
  As they get older, around age 2 to 3 months, place infants on their stomachs while awake to develop neck and back muscles. Also, allow babies who can crawl or walk to explore the home by placing them on the floor. However, do not leave them unattended and make sure the home is childproof.
  
  
• Stimulate learning and play. Play music to stimulate an infant’s hearing. Provide babies toys with different textures that encourage them to explore with their fingers. However, make sure the toys are safe and age-appropriate. Most toy manufacturers label new toys for specific age groups. Also sing, recite rhymes and do finger plays (e.g., peek-a-boo) with a baby.
  
  
• Nurture language development. Talk and read often to a baby – and name objects while pointing to pictures in a book. Use simple words that apply to an infant’s everyday life. Various studies indicate that simple conversation lays the groundwork for a baby’s language development – even before they can understand a word.
  
  
• Manage separation anxiety. One can help infants cope with this common fear by making sure they are well rested and fed before leaving them with a babysitter or other caregiver. It may also help to distract a baby, such as with a favorite toy, at such times.
  
  
• Take care of personal health. Because parenting can be physically, mentally and emotionally draining, it is recommended that parents take time to take care of themselves. This can be done by eating a well-balanced, healthful diet and getting adequate rest and exercise.

Preparing questions in advance can help parents have more meaningful discussions with physicians regarding their infant’s conditions. Parents and other caregivers may wish to ask their baby’s pediatrician the following questions regarding infancy development:

1. My newborn rarely feeds and often falls asleep while I am feeding him/her. Is this a sign of an illness?
   
   
2. I’m not producing enough milk to continue nursing my newborn. Will switching to formula cause any digestive problems?
   
   
3. My infant always vomits after feedings. Is this a sign of disease?
   
   
4. My newborn often seems cross-eyed. Is this normal?
   
   
5. My 3-month-old makes no attempt to lift the head when lying face down. Is something wrong?
   
   
6. My 9-month-old has not started crawling yet. Is this normal?
   
   
7. What milestones should I watch for and at what ages?
   
   
8. How long should I wait after noticing a developmental delay before calling?
   
   
9. Will my second child develop at the same rate as my first?
   
   
10. I have twins. Should they reach milestones at the same time?