OK, so technically you're not pregnant yet, but your due date is based on the first day of your last period, which is considered week one of your pregnancy.
What's happening to baby: Nothing yet, but as soon as fertilization occurs, your baby will begin undergoing thousands of changes over the next 40 weeks.
What's happening to Mom: As you prepare for this long journey, start cleaning up your diet, eliminating drugs, alcohol and caffeine, and ask your doctor about taking a prenatal vitamin.
Ovulation, which may occur this week, kick starts everything. Consider investing in an ovulation detector so you know exactly when ovulation occurs. For most women, it's between days 11 and 21 of your cycle.
What's happening to baby: Nothing yet!
What's happening to Mom: During ovulation (when your ovary releases an egg), your chances of conception increase. The uterine lining is developing to prepare for a fertilized egg.
You're pregnant! But a pregnancy test won't confirm it yet, so you have to wait it out. In the meantime, the guessing game can begin: Your baby's gender, eye color and hair color have already been determined. Who will he (or she) look like? Will she get your blond locks?
What's happening to baby: The fertilized egg, now a ball of cells, is called a blastocyst when it arrives in your uterus, attaching to the lining, where it will spend the next nine months. Right now, it's the size of the head of a pin.
What's happening to Mom: You probably won't feel anything, though some women do feel cramps and notice a heavier vaginal discharge.
At the end of this week, a pregnancy test may confirm your pregnancy. How will you share the news?
What's happening to baby: Your baby is still teeny tiny, and consists of layers of cells that will become his organs and tissues.
What's happening to Mom: You may notice some cramping and bleeding as your baby is implanting inside your uterus. And some women even feel pregnancy symptoms, many of which are similar to those you feel each month before your period begins (backache, headache, breast tenderness, etc.)
You've taken the test and gotten a positive result, but your doctor probably won't want to see you until you're eight or 12 weeks along. Until then, make sure you're eating right. Do ask for a prescription for a prenatal vitamin, and start taking it daily.
What's happening to baby: Your baby is only 0.118 inches long, from head to rump, and his heart is beating steadily, while his skeleton begins to form.
What's happening to Mom: Morning sickness usually begins around week six, but some women experience it earlier. To combat morning sickness, which can occur around the clock, eat several small meals during the day and avoid any foods with strong odors.
Are you itching to share your news? Many women wait until the end of the first trimester, when the risk of miscarriage is lower, but some can't resist telling family and at least a few close friends. Have you blabbed yet?
What's happening to baby: The brain, lungs, arms, legs and nervous system are all beginning to form.
What's happening to Mom: In addition to morning sickness, you may find yourself gaining or even losing weight, if that nausea means you're eating less. You may also have darkened areola and breast soreness.
Next week your doctor may want to see you for your first prenatal visit. Make a list of any questions you have, and ask your partner if he wants to join you.
What's happening to baby: Baby's organs, hair, eyelids and umbilical cord are all forming. Your little one is now about an inch long and weighs less than a single aspirin!
What's happening to Mom: You may have gained or even lost a few pounds, but no one can tell by looking at you that you're growing a baby in your belly. But you are, so take it easy if you're nauseous or tired.
Feeling sleepy? The first trimester is a time of exhaustion for many moms-to-be. Steal naps whenever -- and wherever -- you can. Your body is working overtime and you deserve the rest!
What's happening to baby: Your baby is now the size of a bean. His ears, bones, fingers, toes, eyes, ears, lips and nose are all in the process of forming.
What's happening to Mom: You've got up to 50 percent more blood circulating in your body and your uterus is now the size of a grapefruit (it will get much, much bigger).
Between exhaustion and morning sickness, exercise may be the last thing on your mind, but experts do recommend that pregnant women stay active. It can help prevent excess weight gain, boost energy and help you get your Zzzs. So take a daily walk, hit the gym or try prenatal yoga to stay in shape.
What's happening to baby: Your baby is now the size of a grape, and the tail at the bottom of his spinal cord is now gone. The heart now has four chambers, just like yours.
What's happening to Mom: You may feel more fatigued, thanks to hormonal changes, trouble sleeping and morning sickness. If you are having difficulty sleeping, you might want to change your sleeping position.
You're a quarter of the way there, and you may not even feel pregnant yet! Don't worry, that will soon change, as baby -- and you -- start gaining weight and you feel those first amazing kicks.
What's happening to baby: Your baby is now the size of a lime, and his head is much bigger than the rest of his body.
What's happening to Mom: You're gaining weight, and may have switched over to maternity wear, or maybe you're wearing pants and skirts with elastic waists. If you're at a healthy weight, experts recommend you gain 25 to 35 pounds. That doesn't mean you're eating for two: It means you should take in an extra 300 calories or so a day.
You're almost at the end of your first trimester, which means your utter exhaustion and morning sickness should go away soon.
What's happening to baby: Baby is moving all over the place, but you can't feel it yet. He now weighs half an ounce or so, and his bones are starting to harden.
What's happening to Mom: If you're dealing with headaches, blame rising hormone levels, increased blood volume, stress and lack of caffeine.
You may get your first look at baby this week at your first trimester ultrasound. The American Congress of Obstetricians and Gynecologists recommends nuchal translucency ultrasound around this time to measure your baby's risk of Down syndrome.
What's happening to baby: This week, your baby's facial features take on a more normal appearance as the eyes and ears move closer to their final positions. Your baby's kidneys may have begun to secrete urine and nerve cells are multiplying at a rapid rate. Your baby is developing more complex reflexes and may begin sucking. Stimulating certain points of your uterus may cause your baby to move, but you won't feel the movement for several more weeks.
What's happening to Mom: You probably don't need maternity clothes at this point, but your uterus has expanded to the point where your doctor can feel it in your lower abdomen. You may begin to notice changes in your skin including a darkening of the areola and the appearance of dark patches on your face and neck.Your skin may look great, with that pregnancy glow, or you may be dealing with breakouts or mask of pregnancy (dark splotches on your face, thanks to increased pigmentation).
By now, if you're having twins (or more!), you should know it, as either a blood test or ultrasound can confirm a multiple pregnancy.
What's happening to baby: Your baby, who now weighs 1 ¼ ounces, has fingerprints and a soft layer of hair covering his skin. This hair may still be visible at birth, but will eventually go away.
What's happening to Mom: Your health care provider will want to see you every four weeks to check your weight, blood pressure and urine; measure your uterus; and listen to the baby's heartbeat. Don't miss a single appointment!
With the fatigue, morning sickness and weight gain of the first trimester, your boss may have already figured out that you'll soon be taking a leave of absence, but you still have to make the announcement. Plan what you'll say ahead of time, then go in and share your exciting news!
What's happening to baby: This week, baby weighs a bit less than 2 ounces (a bar of soap weighs 3 ounces) and continues to grow at an astonishing rate.
What's happening to Mom: Your risk of miscarriage is lower now that you're in the second trimester. You should have some of your energy back, and you may even be starting to show. Enjoy the second trimester: You'll feel more like yourself, without the struggles of the first and third trimesters.
Sleep is much easier in the second trimester; just try not to sleep on your back, as it can decrease circulation to your heart.
What's happening to baby: Your little bundle of joy now measures nearly 5 inches long, and her eyes and ears continue to develop. If you could sneak another peek at baby, you might see her sucking her thumb!
What's happening to Mom: Around this time, your doctor may offer you a triple screen or a quad screen to test for Down syndrome, trisomy 18 (a genetic disorder that infants usually don't survive) and neural tube defects (problems with the development of the brain or spinal cord).
You'll likely be seeing your doctor for another checkup soon, so be sure to share any questions or concerns you might have.
What's happening to baby: Baby now weighs 2 ½ ounces. She looks more and more like a baby and her heart pumps some 25 quarts of blood every day.
What's happening to Mom: Sometime in the next few weeks, you should feel baby's first movement, called "quickening." By the end of your pregnancy, baby's gymnastics will be hard to ignore!
You're pregnant during flu season, the Centers for Disease Control and Prevention recommends that you get a flu shot to keep you and your baby healthy. Your ob/gyn might be able to vaccinate you.
What's happening to baby: Baby now weighs 4 ounces and is developing fat under her skin. As your pregnancy progresses, she'll add to these fat stores, which will give her energy and keep her warm when she enters the world.
What's happening to Mom: Your breasts are getting ready to provide milk to your baby, so you may notice that they're growing larger and that more veins are visible.
You're nearly halfway through your pregnancy. How's your partner holding up? Tell him specific ways he can help you as your pregnancy progresses, whether you want him to come to your doctor's appointments, help out more around the house or just rub your aching back.
What's happening to baby: Grow baby, grow! She's now more than 6 inches long and her ears are working. She might even be able to hear loud noises, in addition to the sound of your beating heart and growling stomach.
What's happening to Mom: You know the dangers of high blood pressure, but you may also experience low blood pressure during your pregnancy, as your circulatory system expands at this time. Ward off any dizziness by making sure you don't stand up too quickly.
How are you holding up? If you're dealing with back pain, headaches or other nagging pains, talk to your doctor before you take any medication to make sure they won't harm your baby.
What's happening to baby: Baby weighs in at about 7 ounces this week, and he is starting to grow hair!
What's happening to Mom: You may start experiencing round ligament pain, a sharp pain in your stomach or hip caused by stretching of the round ligament, which supports your uterus.
Right about now, you're likely going in for an ultrasound, and you might be able to find out baby's gender, if you're so inclined. If you do, you can really step up your nursery-planning and name-choosing!
What's happening to baby: Baby now weighs 9 ounces and she might be putting pressure on your lungs and bladder.
What's happening to Mom: Your 20-week ultrasound is a chance for your doctor to see how the baby's growing, check out the placenta, amniotic fluid, look for birth defects and, of course, determine the baby's gender.
How's the name game going? Check out the top 10 names from 2010, courtesy of the Social Security Administration.
What's happening to baby: Baby is now big enough to be measured from his head to heel. He's now roughly 8 ½ inches long and is producing meconium, which will become his first poop when he's born.
What's happening to Mom: Swollen ankles, hands and feet are common in pregnancy -- after all, you've got a lot of extra fluid in your body right now! But if you notice sudden swelling in your hands and face, call your doctor. These are symptoms of preeclampsia, or dangerously high blood pressure.
If you'd like to fit in a babymoon, or one last pre-baby getaway, better do it soon. It's best to travel before you reach 28 weeks. If you fly, be sure to drink plenty of fluids and get up and move around every hour or so.
What's happening to baby: Baby weighs 14 ounces and is looking more and more like a newborn: Her eyes are fully formed, her lips are becoming more noticeable and she even has eyebrows! At 22 weeks pregnant, an expectant mother is in the middle of her second trimester and may start to feel some movement in the womb. The baby is approximately 10 inches and nearly a pound. Her organs are developing at a rapid rate and she may now be moving her limbs and exploring her face. Lips, eyelids and eyebrows are more defined and although her eyes have formed, the iris lacks pigment.
What's happening to Mom: Thanks to a surge of hormones, there are lots of changes for mom too. Her hair is more lustrous and her nails are growing at a more rapid rate. Stretch marks usually appear around this time and skin may take on different textures or shades due to increased melanin. Nipples and areolas often get darker and larger. Some women's feet begin to swell at this point, often going up a half or whole shoe size. Your growing uterus is nearly an inch above your belly button, and you're probably feeling pretty good: not too uncomfortable, and with energy to spare!
Do leg cramps wake you up at night? They're a common pregnancy complaint. Getting regular exercise and stretching your legs before you hit the sheets may help prevent them.
What's happening to baby: Your baby has hit the 1-pound mark! If you're having a boy, his testes are making their descent; if you're having a girl, she's already developed her uterus and ovaries.
What's happening to Mom: You're probably running to the bathroom more than ever, as your growing uterus continues to put pressure on your bladder.
Many moms- and dads-to-be give their baby a cute, weird or amusing nickname like Peanut, Lemon or Chaka Khan before she's born. Does your baby have an in utero nickname?
What's happening to baby: Baby is slightly more than a foot long, and her lungs and brain are growing quickly.
What's happening to Mom: In the next few weeks, you'll be screened for gestational diabetes. You'll have to fast overnight, then swallow a super-sweet drink to test your blood sugar. If it's high and you're diagnosed with gestational diabetes, you'll have to follow a special diet and may also need medication. Untreated, gestational diabetes can cause problems for your baby, such as trouble breathing and other health problems.
Many moms-to-be have cravings throughout their pregnancies, whether it's for something they can't have, like a glass of wine, something they'd never normally eat, like a burger for a vegetarian or something that's just plain weird: Pickles and ice cream, anyone? Some women even crave dirt, chalk or other non-edibles. If you're among this last group, contact your doctor.
What's happening to baby: Your 13-inch-long baby is busy packing on weight, so when she arrives, she'll have that irresistible baby fat. She's also probably moving around quite a bit -- when she's not sleeping!
What's happening to Mom: Your uterus is now the size of a soccer ball. And you may notice some seemingly unrelated to pregnancy symptoms, like a stuffy nose, snoring or frequent nosebleeds. These things actually are pregnancy-related, as the increased blood flow throughout your body can restrict airflow in your nose and airway.
You're almost there -- just 14 weeks to go! If your baby were born now, there's a very good chance he'd survive: 80 percent of babies born at this time do, according to the March of Dimes.
What's happening to baby: By the 26th week of pregnancy the fetus has grown to about one or two pounds. The baby has also begun to inhale and exhale amniotic fluid, an important part of developing his or her lungs. During the 26th week, the baby's ears have developed enough to allow him or her to hear noises outside of the womb. If it is a boy, his testicles will begin to make their descent to the scrotum, a process which typically takes two or three days.
What's happening to Mom: How much weight have you gained so far? If you were at a healthy weight pre-pregnancy and haven't been going overboard when it comes to food, you've likely gained 16 to 22 pounds, but every woman is different. Your health care provider will let you know if you're gaining too much -- or too little -- weight. The 26th week of pregnancy can also often bring with it an increase in blood pressure and a few hormonal changes that can cause lower back pain.
As your second trimester comes to an end, start looking into labor and child care classes, consider taking a tour of the hospital (if it's offered) and ask your mom friends for pediatrician recommendations.
What's happening to baby: He or she may get hiccups more and more often as your pregnancy progresses, and you'll be able to feel her hiccupping. The fetus has grown to about two pounds and 14 inches in length. He or she is also able to open and close their eyes for the first time and the baby will begin to develop to more regular sleep cycle.
What's happening to Mom: Along with all the changes your body is going through, you may also be developing stretch marks on your belly or breasts. Unfortunately, you can't prevent them, but they will become less noticeable after the baby is born. More changes will begin to take place in the body. She will often experience more leg cramps because of baby weight that has been tacked on to her body. The expecting mother may also notice that she has a little less energy than she did during her first trimester.
You're in the home stretch now! Welcome to the third trimester. Swollen fingers and hands may mean you can no longer wear your wedding and engagement rings. Don't want to go without? Slip them on a chain and wear them as a necklace.
What's happening to baby: Baby weighs about 2 ½ pounds, and she will be adding weight quickly in the next several weeks. Her brain is hard at work, becoming more complex and growing more tissue.
What's happening to Mom: In the next few weeks, you may be fighting off leg cramps, constipation, hemorrhoids, sleeplessness and other annoyances. Take it easy as much as you can, and remember, it will all be over soon!
Your doctor may suggest that you do kick counts -- taking time every day to see how often your baby is moving. Ideally, you should feel at least 10 movements (everything counts, from harsh kicks to barely-there flutters) in two hours.
What's happening to baby: He weighs nearly 3 pounds, has eyelashes and has opened his eyes!
What's happening to Mom: As your skin stretches to accommodate your growing belly, you may be dealing with itchy skin. Ease the itch by keeping your belly moisturized.
If you're planning on donating or storing your baby's cord blood, you should get the paperwork in order before you deliver your baby. The American Academy of Pediatrics encourages donating the blood rather than paying the hefty fees for for private storage.
What's happening to baby: Baby's eyes are quickly maturing: She can tell the difference between light and dark and can focus on light. By the 30th week, the average fetus will weigh about three pounds. More than a pint of amniotic fluid surrounds the fetus, though the amount of liquid will decrease as the baby grows and takes up more room in the womb. The fetus will begin to mimic breathing by pushing up the diaphragm up and down.
What's happening to Mom: At this point, Mom may have trouble sleeping and can feel clumsier than usual. Mood swings are also common during the 30th week of pregnancy, as are bouts of depression. Are you getting nervous about labor? Talk to your doctor about your options for pain relief and ask her any questions you might have.
By now, you should have a rough idea of who's going to take over your workload while you're out of the office. Brief your boss, employees and coworkers about what needs to be done while you're on your maternity leave, in case you deliver earlier than expected.
What's happening to baby: Baby is 15 ½ inches long and may weigh about 4 pounds by now.
What's happening to Mom: At this point in your pregnancy, your breasts are bigger and may have stretch marks. They may also be leaking a yellowish liquid. It's nothing to worry about: The colostrum, or pre-milk, that's coming from your breasts now will also come out in the first few days after your baby is born before changing over to the milk that will nourish your baby, if you decide to breastfeed.
You may be feeling Braxton Hicks contractions by now. These "practice" contractions can last for up to two minutes as your uterine muscles tighten. When you feel them, don't panic, just do some deep breathing. And if you're at all concerned that it's the real thing, call your doctor.
What's happening to baby: Baby weighs roughly 4 ½ pounds and is practicing breathing in preparation for her birth.
What's happening to Mom: As baby grows bigger, your uterus may begin putting pressure on your diaphragm, making it harder for you to breathe. This is another reason to take it easy in these final weeks of pregnancy.
Take a few minutes now, while you have the time, to call your insurance company and find out what -- if anything -- they need from you, your employer or your doctor before or after your baby arrives.
What's happening to baby: Baby now measures about 16 ½ inches from head to foot, and is steadily gaining weight.
What's happening to Mom: Got heartburn? Blame your ever-expanding belly. To prevent it, eat smaller meals more often throughout the day, and avoid heartburn triggers, such as citrus foods, soda and fried or spicy foods.
Once you get baby's car seat, call your local police or fire department. In many states, they'll install the seat for you, or will check to make sure you've done it correctly to ensure that your baby is safe when riding in the car.
What's happening to baby: He weighs about 5 pounds and is roughly 17 ½ inches long. Baby's bones are starting to harden, except for the bones in his skull, which stay soft until after birth, to make delivery possible.
What's happening to Mom: As you wait for baby to arrive, you're probably feeling more uncomfortable than ever and not sleeping well. Many moms-to-be worry that their water will break at work or in public. But it's not that dramatic for most women, and, luckily, it usually happens at night when you're sleeping. If you start leaking an odorless fluid, call your doctor.
This week, your doctor may test you for group B streptococcus, a bacteria you may carry that can cause health problems in your baby. If you test positive, you'll get antibiotics during delivery to reduce the risk of passing it to baby.
What's happening to baby: Her lungs are nearly fully developed, and she may weigh up to 6 pounds by now! She's likely in position for delivery, too.
What's happening to Mom: As baby's arrival gets closer, you'll get some relief from your breathing problems as baby drops into your pelvis. This stage, called lightening, makes it easier to breathe, but now baby is putting more pressure on your bladder, which may mean more trips to the restroom than ever before. Lightening can also increase pressure on your bladder.
It's hard to imagine it now, but many women actually miss being pregnant: The constant attention from strangers, feeling those comforting kicks throughout the day and night and the built-in excuse to indulge in chocolate.
What's happening to baby: Baby weighs anywhere from 5 ¾ to 6 ¾ pounds and may be as long as 19 inches. The little hairs that were covering her entire body are starting to go away as she prepares for her arrival.
What's happening to Mom: Talk to your doctor about what to expect during delivery. You may not be planning for a Cesarean section, but you should be prepared in case it happens. According to data from the Centers for Disease Control and Prevention, a full 31 percent of all deliveries are C-sections.
This week, your baby is officially full-term. You made it! Of course, it's best for him to stay where he is until he's ready, and in some cases, that may mean another four weeks.
What's happening to baby: He's now weighing in at around 7 pounds. If he's in breech position, your doctor may be able to turn him around so he's in the head down position.
What's happening to Mom: You probably won't gain much more weight after this week. In the next few weeks, you may lose your mucus plug, which blocks the cervix throughout your pregnancy, keeping your baby safe from bacteria. You may not even notice when you pass the mucus plug, but it means your cervix is beginning to dilate, a process that can take hours, days or weeks.
It's time for final preparations: If you haven't packed your hospital bag yet, do it now. Make sure you have a car seat ready to bring baby home from the hospital and give your partner a list of people to call and e-mail once baby arrives.
What's happening to baby: These last few weeks, baby is mainly just gaining weight and her brain and lungs are still maturing. By now, she may weigh up to 7 ½ pounds. The baby has also developed a firmer grasp and his or her organs have developed enough to sustain life outside the womb. Fingernails have also begun to develop.
What's happening to Mom: In these last few weeks, you're likely still experiencing back pain, sleeping fewer hours than ever and dealing with swelling, mainly in your feet. Excessive swelling should be reported to the doctor if it does not subside. Any odd symptoms such as severe headaches or excessive weight gain should also be reported to a doctor immediately.
Once your baby arrives, you'll have little time for cooking, so consider freezing a few make-ahead meals, like lasagna and casseroles. Later, you'll be glad you did.
What's happening to baby: Baby weighs anywhere from 6 ½ to 8 pounds and is 18 to 20 1/2 inches long. The fat her body is developing will help her regulate her body temperature outside the womb.
What's happening to Mom: You're likely seeing your doctor weekly now, and pelvic exams will help him or her determine baby's position and whether (or how much) your cervix is dilated.
Welcome, baby! Your little one should make his appearance any day now, and you're likely desperate to meet him! Enjoy every minute.
What's happening to baby: At birth, he'll weigh between 6 ¾ and 10 pounds and will be between 19 and 21 inches long, though, of course, every baby is different. Several months after birth, the soft spots on his skull will begin to harden.
What's happening to Mom: You're probably anxious, excited and ready to meet the little person growing inside of you. Try to be patient if you go past your due date -- you'll have the rest of your life to spend time with your baby.