Week 21
Your baby's development
The amniotic fluid that has cushioned and supported your baby in the uterus now serves another purpose. The intestines have developed enough that small amounts of sugars can be absorbed from the fluid that is swallowed and passed through the digestive system to the large bowel. Almost all of your baby's nourishment, however, still comes from you through the placenta.
Until now your baby's liver and spleen have been responsible for the production of blood cells. But now the bone marrow spaces are developed enough to contribute to blood cell formation as well, and bone marrow will become the major site of blood cell production in the third trimester and after birth. (The spleen will stop producing blood cells by week 30, and the liver will stop a few weeks before birth.)
Your body
Is exercise safe during pregnancy? Exercise can be a great way to stay in shape during pregnancy and can even keep some symptoms — such as varicose veins, excessive weight gain, and backache — to a minimum. But pregnancy is not the time to start training for a triathlon — going slowly is the name of the game. Because ligaments become more relaxed during pregnancy, you're at higher risk for injury, so low- or non-impact exercise such as yoga, swimming, and walking are your best bets. Talk to your health care provider before beginning any exercise program while you're pregnant.
Week 22
Your baby's development
The senses your baby will use to learn about the world are developing daily. Taste buds have started to form on the tongue, and the brain and nerve endings are formed enough so that the fetus can feel touch. Your baby may experiment with this newfound sense of touch by stroking his or her face or sucking on a thumb, as well as feeling other body parts and seeing how they move.
Your baby's reproductive system is continuing to develop, too. In boys, the testes have begun to descend from the abdomen, and in girls, the uterus and ovaries are in place and the vagina is developed.
Your body
You may soon notice your uterus practicing for delivery with irregular, painless contractions called Braxton Hicks contractions. You may feel a squeezing sensation in your abdomen. Don't worry, though: Your baby may be able to feel the contraction as it squeezes the uterus, but Braxton Hicks contractions aren't dangerous or harmful. If, however, the contractions become more intense, painful, or frequent, contact your health care provider immediately because painful, regular contractions may be a sign of preterm labor.
Week 23
Your baby's development
Even though fat is beginning to accumulate on your baby's body, the skin still hangs loosely, giving your baby a wrinkled appearance. Your baby's daily workout routine includes moving the muscles in the fingers, toes, arms, and legs regularly. As a result, you may feel more forceful movements.
By now your baby weighs a little more than 1 pound (454 grams). If preterm labor and delivery were to occur this week, a baby could survive with expert medical care, but might have mild to severe disabilities. With increasing research and knowledge in the field of fetal medicine, the prognosis for premature babies (preemies) improves every year.
Your body
The closer you get to your delivery date, the more trouble you may have sleeping. Anxiety, frequent urination, heartburn, leg cramps, and general discomfort can translate into a short night's sleep for a pregnant woman. But your baby's health and your own depend on you getting adequate rest. Try a warm bath, soothing music, a relaxing book, or a cup of herbal tea to put you in the mood to snooze.
Many doctors recommend that pregnant women sleep on their sides, not their backs or stomachs, so that blood flow to the placenta is not restricted. If you find this uncomfortable, try placing a pillow between your knees to relieve the pressure of your weight while lying on your side.
Week 24
Your baby's development
Your baby is still receiving oxygen through the placenta. But once birth occurs, his or her lungs will start taking in oxygen on their own. In preparation for that, your baby's lungs are developing the ability to produce surfactant. Surfactant is a substance that keeps the air sacs in our lungs from collapsing and sticking together when we exhale, allowing us to breathe properly.
Because the inner ear — which controls balance in the body — is now completely developed, your baby may be able to tell when he or she is upside down or right side up while floating and making movements in the amniotic fluid.
Your body
An important prenatal test, glucose screening, is usually performed sometime during weeks 24 to 28. The glucose screening test checks for gestational diabetes, a temporary type of diabetes that occurs during pregnancy and can cause problems in the newborn, such as low blood sugar. Gestational diabetes may also increase the chances that a woman would need a cesarean section because it can lead to the big growth of babies.
During the glucose screening test, you'll drink a sugary solution and then have your blood drawn. If your blood sugar levels are too high, you'll have further tests, which your health care provider will discuss with you. Gestational diabetes usually can be controlled by eating a well-planned diet and getting regular exercise, but sometimes medication, such as daily insulin, will be needed during the pregnancy.
Week 25
Your baby's development
You may notice that your baby has resting and alert periods. You'll notice fetal activity more readily when you are more sedentary. Your baby's hearing has continued to develop, too — he or she may now be able to hear your voice!
Your body
Pregnancy can cause some unpleasant side effects when it comes to digestion. Not only does the hormone progesterone slow the emptying of the stomach, but it also relaxes the valve at the entrance to the stomach so that it doesn’t close properly. This allows acidic stomach contents to move upward into the esophagus. The result: reflux (also known as heartburn) that can make eating your favorite meals a nightmare. The expanding uterus puts additional pressure on the stomach in the last few months of pregnancy. Try eating smaller, more frequent meals, and avoid spicy and fatty foods.
Week 26
Your baby's development
Although your baby's eyes have been sealed shut for the last few months, they will soon open and begin to blink. Depending on ethnicity, some babies will be born with blue or gray-blue eyes (which may change color in the first year of life) and some will be born with brown or dark eyes. Eyelashes are growing in, as is more hair on the head.
Your baby, weighing a little less than 2 pounds (907 grams), still looks wrinkly but will continue to gain weight steadily over the next 14 weeks until birth.
Your body
Your uterus provides a safe haven for your baby before birth. But what about after delivery? Your baby will be moving about your home in what seems like no time at all. Take the time now to safeguard your home by babyproofing. Covering electrical outlets, removing choking hazards, installing smoke alarms, and blocking off staircases are just some of the steps to ensuring your child's safety. Take every precaution you can think of, but remember: No amount of babyproofing can substitute for careful supervision of your child.
Week 27
Your baby's development
By this first week of the third trimester, your baby looks similar to what he or she will look like at birth, except thinner and smaller. The lungs, liver, and immune system still need to fully mature, but if born now, your baby would have a very good chance of surviving.
As hearing continues to develop, your baby may start to recognize your voice as well as your partner's. Sounds may be muffled, though, because the ears are still covered with vernix, the thick waxy coating that protects the skin from becoming chapped by the amniotic fluid.
Your body
Your body instinctively nourishes and protects your baby during pregnancy, but caring for a newborn is a learned skill. Consider signing up for childbirth classes through your local community center or hospital to learn about topics such as labor, options for pain relief, what to expect after delivery, common newborn problems, babyproofing, breastfeeding and formula feeding, and infant CPR. Learning all you can about birth and babies will help you feel more confident, especially if you're a first-time parent.
Week 28
Your baby's development
Your baby now weighs about 2 pounds, 2 ounces (1,000 grams) and measures about 10 inches (25 cm) from crown to rump. At your next prenatal appointment, your health care provider may tell you whether your baby is headfirst or feet- or bottom-first (called breech position) in the womb. Babies who are in the breech position may need to be delivered by cesarean section. Your baby still has 2 months to change position, though, so don't worry if your baby is in the breech position right now. Most babies will switch positions on their own.
The folds and grooves of your baby's brain continue to develop and expand. In addition, your baby continues to add layers of fat and has continued hair growth.
Your body
Your health care provider probably sent you for some blood tests early in your pregnancy. One thing blood tests measure is the Rh factor, a substance found in the red blood cells of most people. If you don't have it (if you’re Rh negative) but your baby does (is Rh positive), there is potential for your baby to have health problems, such as jaundice and anemia. Your doctor can prevent these problems by giving you a vaccine called Rh immune globulin at 28 weeks and again after delivery.
Week 29
Your baby's development
Your baby continues to be active, and those first few flutters of movement have given way to hard jabs and punches that may take your breath away. If you notice a decrease in movement, do a fetal kick count: your baby should move at least 10 times in an hour. If your baby moves less, talk to your health care provider.
Your body
During pregnancy, iron is important for replenishing the red blood cell supply. You should be eating at least 30 milligrams of iron each day. Because iron deficiency is common during pregnancy, your health care provider may recommend that you receive a blood test to check your iron level. If it's low, you may be prescribed an iron supplement.
Week 30
Your baby's development
Now weighing about 3 pounds (1,400 grams) and measuring about 10.8 inches (27 cm) from crown to rump, your baby continues to gain weight and layers of fat. This fat makes the baby look less wrinkly and will help provide warmth after birth.
In preparation for respiration after birth, your baby will mimic breathing movements by repeatedly moving the diaphragm. Your baby can even get the hiccups, which you may feel as rhythmic twitches in your uterus.
Your body
Constipation is a common complaint of pregnancy. The pregnancy hormones that allow you to maintain your pregnancy also slow the digestive process considerably. Exercising regularly and eating foods high in fiber, such as vegetables and whole grains, are great ways to keep everything regular.
Week 31
Your baby's development
By now your baby is urinating approximately several cups of urine a day into the amniotic fluid. He or she is also swallowing amniotic fluid, which is completely replaced several times a day. Excess fluid in the amniotic sac (known as polyhydramnios) may mean that the baby isn't swallowing normally or that there is a gastrointestinal obstruction. Inadequate fluid in the amniotic sac (oligohydramnios) may mean that the baby isn't urinating properly and could indicate a problem with the kidneys or urinary tract. Your health care provider will measure your levels of amniotic fluid as part of your routine ultrasound.
Your body
Have you decided whether to breastfeed or formula feed your baby? Although the American Academy of Pediatrics (AAP) recommends breast milk as the best form of infant nutrition, the decision about how to feed your child is a personal one. Talk to your health care provider or a lactation consultant if you need more information before making your choice.
The milk glands in your breasts may have started to make colostrum by now. Colostrum is the pre-milk that provides your baby with calories and nutrients for the first few days before your milk comes in if you plan to breastfeed. For some women, it is thin and watery. For others, it is thick and yellowish. If you notice your breasts leaking colostrum, you can buy disposable or washable breast pads to protect your clothing.
Week 32
Your baby's development
The final touches are being placed on your baby masterpiece. Eyelashes, eyebrows, and the hair on your baby's head are evident. The lanugo hair that has covered your baby since the beginning of the second trimester is falling off, although some may remain on the shoulders and back at birth.
At about 4 pounds (1,800 grams) and 11.4 inches (29 cm) from crown to rump, your baby would have an excellent chance of survival outside the womb if you delivered now.
Your body
During your prenatal visits, your health care provider will monitor your blood pressure, urine, and any swelling that may develop, but symptoms such as sudden weight gain, swelling in the hands or face, headaches, or changes in vision can be signs of preeclampsia. This condition causes high blood pressure and protein in the urine. Be sure to tell your healthcare provider if you experience any of these symptoms, since this condition can affect both the mother and fetus during the second half of pregnancy.
Week 33
Your baby's development
In these last few weeks before delivery, the billions of developed neurons in your baby's brain are helping him or her to learn about the in-utero environment — your baby can listen, feel, and even see somewhat. Your baby’s eyes can detect light and the pupils can constrict and dilate in response to light. Like a newborn, your baby sleeps much of the time and even experiences the rapid eye movement (REM) stage, the sleep stage during which our most vivid dreams occur!
Your baby's lungs are almost completely matured. Fat will continue to be deposited on your baby's body for protection and warmth. Babies gain a good deal of their weight in the final few weeks before birth.
Your body
With labor and delivery only 2 months away, you may be considering how you'll cope with pain during childbirth. Among the things you'll want to learn about are the most commonly used techniques for pain relief. These include breathing techniques such as those taught in Lamaze classes, pain-relief medications given through injection, and epidurals, where doctors can give an anesthetic by means of a soft, thin catheter that's placed in your lower back. Whatever your ultimate choice, the more you know, the better informed your decision can be. Although you don't have to make a decision yet, talk to your health care provider now about your choices.
Week 34
Your baby's development
Maternal calcium intake is extremely important during pregnancy because the baby will draw calcium from the mother to make and harden bone. If a pregnant woman doesn't get enough calcium during pregnancy, it can affect her own bones because the developing fetus will take minerals from the mother's skeletal structure as needed.
The vernix coating on the baby's skin is becoming thicker, whereas lanugo hair is almost completely gone.
By now most babies will be in position for delivery. Your health care provider can tell you if your baby is positioned head- or bottom-first. Babies born at 34 weeks usually have fairly well-developed lungs, and their average size of 5 pounds (2,250 grams) and 12.6 inches (32 cm) from crown to rump allows them to survive outside the womb without extensive medical intervention.
Your body
Fatigue is a common complaint of late pregnancy. Difficult sleeping, aches and pains, weight gain, and anxiety about labor, delivery, and taking care of a newborn may contribute to your exhaustion. Rest as much as you can and take naps if possible.
Week 35
Your baby's development
Your baby already weighs about 5 pounds, 5 ounces (2,400 grams), but this week begins your baby's most rapid period of weight gain — about 8 to 12 ounces (226 to 340 grams) each week! Fat is being deposited all over your baby's body, especially around the shoulders.
Because of this increasing size, your baby is now cramped and restricted inside the uterus — so fetal movements may decrease, but they may be stronger and more forceful. If your baby is in a headfirst position, his or her head will rest on your pubic bone in preparation for labor.
Your body
The bond you may already feel with the baby growing inside of you will only grow stronger once your baby is born. Bonding — the intense attachment that develops between you and your baby — is not something that only occurs within minutes or days after birth. It may happen later and it may develop over time. Bonding not only makes you want to protect your baby and shower him or her with affection, but it also fosters your baby's sense of security in the world outside your womb.
Week 36
Your baby's development
The wrinkly, tiny fetus you may have seen on earlier ultrasounds has given way to an almost plump baby. There is fat on your baby’s cheeks, and powerful sucking muscles also contribute to your baby's full face. Your baby now weighs a little under 6 pounds (2,721 grams).
The bones that make up your baby’s skull can move relative to one another and overlap each other while your baby’s head is inside your pelvis. This phenomenon is called molding, and it helps the baby pass through the birth canal. Don't be surprised if your baby arrives with a pointy or misshapen head! After a few hours or days, your baby's head will be back to a rounded shape.
Your body
Starting this week, you may begin to see your health care provider every week. Your doctor or midwife may give you an internal exam to determine if cervical effacement (thinning of the cervix) or dilation (opening of the cervix) has begun. You may experience engagement (also known as lightening), which is when the baby drops into the mother's pelvis in preparation for labor. Your appetite may return because the baby is no longer putting as much pressure on your stomach and intestines, and if you've been experiencing heartburn, the baby's descent may somewhat alleviate it.
Week 37
Your baby's development
This week, your baby is considered full-term! But your baby hasn't stopped growing yet. He or she continues to develop fat at the rate of half an ounce (14 grams) a day. In general, boys weigh more than girls at birth.
Your baby has developed enough coordination to grasp with the fingers. If shown a bright light, your baby may turn toward it in your uterus.
Your body
After this week, you may lose the mucous plug that sealed off your uterus from infection. The mucous plug can be lost a few weeks, days, or hours before labor and is thick, yellowish, and may be tinged with blood (the mucous plug is also called bloody show). As the cervix dilates in preparation for the labor, the plug is discharged from the body. Be sure to speak with your health care provider about any discharge you may be having.
Week 38
Your baby's development
Your baby weighs about 6 pounds, 6 ounces (2,900 grams) by now and measures about 13.4 inches (34 cm) in length from crown to rump. Fat is still accumulating, although growth is slower now. You may notice that your weight gain has decreased or ceased.
Since your baby has had the muscles to suck and swallow amniotic fluid, waste material has been accumulating in his or her intestines. Cells shed from the intestines, dead skin cells, and lanugo hair are some of the waste products that contribute to meconium, a greenish-black substance that constitutes your baby's first bowel movement.
If you're having a boy, his testicles have descended into the scrotum, unless he has a condition called undescended testicle. If you're having a girl, the labia are now completely developed.
Your body
Because your baby is engaged in your pelvis, your bladder is extremely compressed, making frequent bathroom trips a necessity.
Have you and your partner made a decision about circumcision? Circumcision is a surgical procedure to remove the foreskin of the penis in male babies. For some parents the decision to circumcise is a religious one. For others, the choice is not as easily made. Talk to your health care provider about the issues surrounding circumcision, including pain relief options for the baby.
Week 39
Your baby's development
Umbilical cords, which carry nutrients from the placenta to the baby, vary in size but average about 22 inches (55 cm) long and half an inch (1-2 cm) thick. Sometimes the umbilical cord can become wrapped around a baby’s neck. Generally, this doesn’t cause problems, although a cesarean delivery could be required if it causes pressure on the umbilical cord during labor or delivery.
Most of the vernix that covered your baby's skin has disappeared, as has the lanugo. Your body has been supplying the baby with antibodies through the placenta that will help the baby's immune system fight infection for the first 6-12 months of life.
Your body
Braxton Hicks contractions may become more pronounced. Also called "false labor," these contractions may be as painful and strong as true labor contractions but do not become regular and do not increase in frequency as true contractions do.
Another sign of labor, the rupture of your amniotic sac, could happen any day now. When their water breaks, some women experience a large gush of water and some feel a steady trickle. Many women don’t experience their water breaking until they’re well into labor. Others need to have their water broken by their health care providers to get their labor started or to speed it up. If you think your water has broken or you are experiencing regular contractions, contact your health care provider.
Week 40
You baby's development
After many weeks of anticipation and preparation, your baby is here! Or maybe not — only 5% of women deliver on their estimated due dates, and many first-time mothers find themselves waiting up to 2 weeks after their due date for their baby to arrive.
A baby born at 40 weeks weighs, on average, about 7 pounds, 4 ounces (3,300 grams) and measures about 20 inches (51 cm). Don't expect your baby to look like the Gerber baby right off the bat — newborns often have heads temporarily misshapen from the birth canal and may be covered with vernix and blood. Your baby's skin may have skin discolorations, dry patches, and rashes — these many variations are completely normal.
Because of the presence of your hormones in your baby's system, your baby's genitals (scrotum in boys and labia in girls) may appear enlarged. Your baby, whether a boy or a girl, may even secrete milk from the tiny nipples. This should disappear in a few days and is completely normal.
Right after birth, your health care provider will suction mucus out of your baby's mouth and nose, and you'll hear that long-awaited first cry. Your baby may then be placed on your stomach, and the umbilical cord will be cut. A series of quick screening tests, such as the Apgar score, will be performed to assess your baby's responsiveness and vital signs, and he or she will be weighed and measured. If your pregnancy was high risk, or if a cesarean section was necessary, a neonatologist (a doctor who specializes in newborn intensive care) will be present at your delivery to take care of your baby right away. If your baby needs any special care to adjust to life outside the womb, it will be given — and then your newborn will be placed in your waiting arms.
Your body
This week you'll experience the moment you've been anticipating — your introduction to your baby! Before you can meet your baby, though, you have to go through labor and delivery. You may have learned about the three stages of birth in your prenatal classes. The first stage of labor works to thin and stretch your cervix by contracting your uterus at regular intervals. The second stage of labor is when you push your baby into the vaginal canal and out of your body. The third and final stage of labor is when you deliver the placenta.
If you don't go into labor within a week of your due date, your health care provider may recommend you receive a nonstress test, which monitors fetal heart rate and movement to be sure that the baby is receiving adequate oxygen and that the nervous system is responding. Talk to your health care provider to find out more about this test.
If your labor isn't progressing, or if your health or your baby's health requires it, your health care provider may induce labor by artificially rupturing the membranes or by administering the hormone oxytocin or other medications. If your pregnancy is high risk, or if there are any other potential complications, you may require a cesarean section delivery.
Some women know ahead of time that they will be delivering via cesarean section and are able to schedule their baby's "birth day" well in advance. If you're one of them, you've probably been able to prepare yourself emotionally and mentally for the birth — which can help to lessen the feelings of disappointment that many mothers who are unable to deliver vaginally experience. But even if you have to undergo a cesarean section that wasn't planned, rest assured that you'll still be able to bond with your baby. It might not be the birth experience you imagined, but your beautiful newborn has arrived nonetheless. The months of waiting are over! Good luck with your baby!