Second Trimester Weekly Pregnancy Calendar: Your Baby and Your Development

A pregnancy is, on average, forty weeks. Each and every week is a new and exciting experience. The following is a weekly pregnancy calendar to give a general idea of what to expect in the second trimester of each week of your pregnancy, as well as how your baby will be growing.

Month Four, Week Thirteen:

How your baby is growing:

Your baby now weighs about an ounce, and is about the length of your finger at approximately three inches long. It's ears have finished developing and it may even be able to hear you! Time to turn on the music. Studies indicate that playing classical music for infants and babies in the womb increases intelligence and reasoning skills later in life. Your baby has also completed developing the gallbladder, pancreas, bladder, kidneys and stomach. It is now busy working on the vocal chords and bone marrow. The intestines that formed earlier are moving from the umbilical cord and into your baby. Your placenta has caught up and now weighs about as much as your baby does.

How you may be changing:

Welcome to the second trimester! All that growing means more weight gain, but there is good news ahead. Most women wave good bye to their morning sickness and fatigue in the thirteenth week even if they are waving hello to some extra pounds. If you haven't let everyone in on the good news, now is an excellent time, before they've guessed you're pregnant. Also, the chance of miscarriage has significantly decreased. Now is also a good time to begin pregnancy yoga or water aerobics. This is not intended to cause weight loss but to maintain muscle tone which can be lost during pregnancy. You may also want to reach for the cocoa butter as your expanding abdomen will be less likely to develop stretch marks if it is well moisturized. Avoid expensive creams that promise miracles. They are a waste of money.

Month Four, Week Fourteen:

How your baby is growing:

Your baby's pancreas is making insulin, it's liver is producing more bile, and it's bone marrow is complete and sending out red blood cells. It is practicing breathing, and even urinating. Your baby's urine will create more amniotic fluid which will accommodate its growth, and it is growing. Your baby now measures about four inches long and weighs one and a half to two ounces. It's body has become covered in a fine layer of hair called lanugo, which will still be present at birth. Many women will have an ultrasound between this week and week sixteen which can finally answer the big question, boy or girl?

How you may be changing:

If your nipples hadn't darkened already they likely will be darker by the end of this week. This may be accompanied by a new dark line running down your navel. The linea negra occurs in most pregnancies and will disappear after you've given birth right along with those darkened nipples and Montgomery's tubercles. Your uterus is now the size of a grape fruit. If you've started prenatal care your practitioner will likely take blood this week, and lots of it, to test for a variety of things including chance of birth defects and anemia.

Month Four, Week Fifteen:

How your baby is growing:

Your baby is beginning to develop details as scalp hair pattern emerges and facial muscles develop. It will grimace and smile practicing expressions for later in life. This week baby may also begin sucking it's thumb or hiccuping. Your baby now weighs about two to three ounces and measures four and a half to five inches in length. All of your baby's organs are functional and it's nerves are now complete. If you could look inside you could see tiny blood vessels through it's thin skin. The heart is now pumping twenty quarts of blood a day through these tiny veins which will later increase to over three hundred at birth.

How you may be changing:

Your body's blood flow as now increased by an amazing twenty percent, and so has your waist line. Avoid trying to cram into your regular clothes and invest in some comfortable maternity gear. Hindering blood flow will only result in more swelling and discomfort. You may also notice a clear fluid leaking from your breasts around this week. This is because milk production can begin very early. If leaking becomes excessive just purchase some breast pads or trim pantiliners to fit. Your uterus has now pushed up and out of your pelvis giving that unmistakable basketball belly of pregnancy.

Month Four, Week Sixteen:

How your baby is growing:

Your new baby is now able to grasp at the umbilical cord and kick at you as coordination improves. This also means you may feel baby move in week sixteen, though it's less likely you'll recognize what it is if you're a first time mother. These first noticeable movements are called "quickening", and are quick to be exciting. If you can't feel your baby move yet, don't be frightened, many mothers don't feel their baby move for another five to six weeks. Your baby now weighs about three to four ounces and measures six and a half to seven inches, that means even at sixteen weeks your baby could fit in the palm of your hand!

How you may be changing:

Your weight gain will continue at about one to two pounds a week, and you now have over a cup of amniotic fluid in the amniotic sack. Many women gain as much as ten pounds by week sixteen, after you add in the increased blood volume and breast size. As the baby begins to move you'll find everyone and their mother just wants to touch and feel your growing belly. Be sure to speak up and be heard if this bothers you. Due to the hormones that are still overly active in your system, even if more stable than in prior weeks, you'll find yourself more emotional than ever before. You may find the simple stress of everyday life is beginning to bring you down. It's important you continue to express yourself, as well as what you do and don't want. People will understand, making a baby is hard work.

Month Five, Week Seventeen:

How your baby is growing:

Bring on the fat! All baby does this week is fatten up. A special kind of fat called brown fat is being deposited all over your little one to keep him/her warm after birth. This brown fat will account for two to six percent of your baby's weight at birth. This week your baby may also begin to move its eyes under the still fused eyelids in a sweeping motion as if dreaming. Loud noises may also startle your baby in your belly. Your baby is about seven to seven and a half inches tall now and finally weighs more than your placenta at about five ounces.

How you may be changing:

Your uterus is now about half way up your naval and you are unequivocally, visibly pregnant. You will notice, in addition to that extra sweat and snot from earlier weeks, you may now be experiencing excess vaginal discharge. This is normal unless the discharge becomes discolored, itchy, has an odd odor, or contains more than trace amounts of blood. Be sure to let your health care provider know if you notice any of these changes. All of these extra secretions will go away after you have the baby.

Month Five, Week Eighteen:

How your baby is growing:

Your baby's bones are now fully hardened and it is continuing to grow rapidly. Your baby will weigh about seven ounces and measure about seven and a half to eight inches long. This week the pads of the feet and finger prints will form. Your baby's retinas will also become light sensitive. If you shine a bring light on your belly, your baby may move away from it even though it's eye lids are still shut. Many babies become far more active at this point in their development where there is still plenty of room to move around.

How you may be changing:

You may be having issues sleeping at night because your growing belly puts pressure on your spine which can cause discomfort. Try propping yourself up with some pillows so you're sleeping on a slight incline. In later weeks this also ensures blood flow to your baby is optimal. Many women also begin to experience more advanced joint pain due to the excessive weight that their bodies are not used to carrying. Don't be afraid to sit down if you're tired even if you haven't been standing for very long. A nice warm bath will also do wonders for the pregnancy woes, but remember not to hit the hot tub. If water is too hot it could harm your baby.

Month Five, Week Nineteen:

How your baby is growing:

Your baby is really starting to put on the weight this week becoming about the size of a medium apple. At this point weight and height begin to vary more from baby to baby, but the average is about eight ounces in weight and between eight and nine inches long. Permanent teeth are forming behind your baby's milk teeth. If your baby is a girl her ovaries are now producing eggs which already contain your future grandchildren. No matter your baby's sex an increase in brain development can be marked this week as traits such as hand dominance are decided. Your baby also becomes more sensitive to emotional stimuli, and will respond negatively to arguments or stress.

How you may be changing:

That weight just keeps piling on. By now your back has likely begun to hurt from either the added weight in your belly, in your bra, or possibly both. As hard as it is try to maintain proper posture. This will strengthen your back muscles and eventually the pain will subside. You may find yourself still plagued with pregnancy worries at this point, and it's time to let them go. At nearly half way there your chances of losing the baby are now very slim. When in doubt do some reading or ask someone you trust. Dwelling on your worries will only stress you and your baby out.

Month Five, Week Twenty:

How your baby is growing:

This week the lanugo becomes covered in a white protective coating called vernix. Vernix is sort of like a wet suit for your baby to protect it's skin from the moisture of your womb. Some babies are born with a bit of vernix still present. The average baby is now about ten inches long and weighs close to ten ounces. Your baby is also now aware of night and day. It will begin to develop sleep and activity time cycles. You'll notice your baby will be most active at certain times of the day, and these habits will likely continue into infancy, so pay attention.

How you may be changing:

Congratulations! You've made it half of the way there. Assuming you give birth on your due date, that is. Many women say it's in week twenty that they have the most energy. Consider using this boost to prepare your nursery or do some shopping for baby and for yourself. You may really be needing those new clothes as your belly begins to bulge even more. Sometimes during pregnancy your belly button may begin to protrude. You may also notice a slight difficulty breathing as your uterus pushes up on your lungs. This shortness of breath will likely continue until your baby drops down into the pelvis during your last few weeks.

Month Six, Week Twenty One:

How your baby is growing:

Your baby now probably weighs around thirteen ounces and could measure anywhere between seven and eleven inches. From this point on your baby's main objective is to put on weight. This means weights will vary even more from baby to baby. Your baby's eyebrows, eyelashes, and eye lids are now fully formed. Though they are still sealed the eyes become more active. During this week taste buds will develop, and the baby may begin to turn to a head down position in which it will remain until your labor. Not all babies turn early in the pregnancy, and some don't turn at all.

How you may be changing:

That excess energy from last week may flow into week twenty-one. Walking or light exercise can be a wonderful way to ensure your body stays toned and healthy during pregnancy. If you experience swelling of the hands after or during walking don't worry. This is from excess fluid in the body pooling in the hands because they've been in a downward position so long. Swelling is actually likely to become common in your whole body due to that excess fluid. You may even find the need for bigger shoes at this time. Your exercise routine should avoid heavy lifting and include kegels. The stronger your pelvic floor is, the easier your labor will be.

Month Six, Week Twenty Two:

How your baby is growing:

In week twenty-two continued growth is pretty much all that occurs. Your baby will likely reach about fifteen ounces this week and grow to be between ten and twelve inches long. Your baby's organ systems are all now becoming functional. It has distinct lips and full sets of teeth under it's gums. Your baby looks like a far smaller version of how it will appear when it comes out. The baby will continue to be very active this week practicing for life outside the womb.

How you may be changing:

Many women experience an increase in sex drive around this week, and increased blood flow can make sex itself more enjoyable. Don't worry about sex hurting your baby either. It's safe and sound in the amniotic sack. Some women find the vaginal area becomes so sensitive from this increase in blood flow, however, that sex can be painful. No matter the circumstance you should keep open communication with your significant other. Sex is an important part of every relationship, and when two people love one another enough to bring life into this world, they can certainly come to an agreement on sex during pregnancy.

Month Six, Week Twenty Three:

How your baby is growing:

A lot more body growth occurs this week as your baby gains more fat and those tiny muscles strengthen. Most babies reach the one pound mark by week twenty-three, and could be up to a foot tall. Your baby's hair color will also begin to develop this week darkening to blond, red, brunette or black as it will be at birth. Though hair and eye color will often change as your baby grows. In fact eye color doesn't normally settle until six months of age. During the months to come your baby's weight will double.

How you may be changing:

You've continued gaining weight too! At this point most mothers have gained upwards of fifteen pounds. Your health care provider will track your growth both by weight, and by measuring the size of your uterus. These measurements can sometimes recalculate an incorrect due date if you were unsure of the date of your last menstrual cycle. The dizziness and light-headedness from earlier weeks may return, and if it does this time you may want to let your doctor know. It can be a sign of anemia or a lack of iron in all that new blood. Many women become anemic while pregnant and it can cause complications during labor.

Month Six, Week Twenty Four:

How your baby is growing:

This week your baby gets wrinkly. This is because skin grows faster than your baby's body can deposit brown fat to fill it in. More fat is deposited this week than before however, and your baby will likely weigh around one pound five ounces. Some babies reach the foot tall mark this week while some remain just below or above the mark. Good news! If your baby is born prematurely at this point it has a chance at survival outside the womb with intensive care. As your babies lungs mature more fully in the coming weeks that chance will only grow.

How you may be changing:

The top of your uterus has now reached your naval and you probably feel the full effect of your pregnancy. This also likely means the addition of heartburn caused by the uterus pushing on the stomach. Antacids are your friend. Though you've entered the safe zone for premature birth, you've only just entered it and survival still has a pretty low success rate. Premature birth tends to happen more in the summer months because of dehydration, so be sure to drink plenty of water and call your doctor immediately if you suspect a premature birth.

Month Seven, Week Twenty Five:

How your baby is growing:

Another great week for growth. The average baby is now around one pound nine ounces and measures upwards of a foot. Your baby has been working on motor skills this week and can now touch its toes, make fists, and kick with more accuracy than you may think, so watch out. Being previously plugged, baby's nostrils also open up this week. If your significant other places their ear on your belly at this point they may be able to hear the tiny heart beat, but they also may get kicked in the head in response to the pressure.

How you may be changing:

Welcome to the final stretch! Your third trimester will soon begin. The bad news? Many women experience a reintroduction of those pregnancy symptoms from the first trimester. Especially fatigue, but who wouldn't be tired carrying that belly around? You may find difficulty in tying your shoes or bending over. Don't be afraid to ask for help. You'll soon be seeing your prenatal care provider more often, and you may be feeling your running out of time. Now is an excellent time for a baby shower to help you get more of those important baby items you need.

Month Seven, Week Twenty Six:

How your baby is growing:

Mommy, we have sound! Your baby's ears finished up developing this week allowing them to hear a wider variety of sounds. The eyes are nearly complete now as well and the lungs have begun to create alveoli. Soon they will begin secreting a substance called surfactant to keep the lung tissue separated. The lungs are one part of your baby that can complicate premature births, so this big step in their advancement is wonderful thing. Your babies veins are still visible through it's skin this week, but it is beginning to turn opaque. Almost all babies have hit that foot tall mark by now and weigh around one and a half to two pounds.

How you may be changing:

Sleeping can be a chore at this point. If you do not already sleep propped by pillows now is the time, because the weight of your baby is now heavy enough to constrict blood flow. Some women find laying on a particular side most comfortable. It's common folk lore that the side you find comfortable during pregnancy will be the side your baby likes to sleep on later in life. You'll be tested for gestational diabetes soon, a temporary condition that many pregnant women develop. Most of the time gestational diabetes will go away after the baby is born. The test requires that you fast for twelve hours prior but aside from that it is painless. An icky tasting drink and one more blood pull complete the test.

Month Seven, Week Twenty Seven:

How your baby is growing:

Your baby now has an eighty-five percent chance of survival outside the womb and looks pretty much like it will when it comes out. The lungs, liver, and immune system haven't fully formed but they are well on their way. Most babies hit the two pound mark this week and measure between twelve to fifteen inches long. In this home stretch your baby's weight will sometimes triple as it plumps up for outside life. Some babies start to become less active as their space fills in, but some rebel and move more. These movements can be painful, but won't likely cause any damage. Some women do report bruising.

How you may be changing:

Most women really begin to pile on the weight from this point on. Just remember that you are not getting "fat" per say you are creating a new life and every pound adds to the health of your new baby. The space inside for your baby has halved from it's growth, and you may actually be able to see it's kicks and jabs on the outside of your belly. This can be an exciting experience. You may begin to see stretch marks this week. Remember that while staying hydrated and using lotions can help reduce stretch marks, their appearance is primarily determined by genetics. Think of them as battle scars of pregnancy.

Be sure to check out all the trimesters of your pregnancy to come for more tips, advice and forewarning for your pregnancy.