Week 1You're actually not pregnant yet—the clock starts ticking from the first day of your last period. So even though pregnancies are said to be 40 weeks long, you only carry your baby for 38 weeks. Read more about being 1 week pregnant.
Week 4Positive test: You're pregnant! You may be starting to feel bloated, crampy, tired and moody, and experiencing sore breasts, nausea/vomiting and a frequent need to pee. But don't worry if you're not—that's normal. Read more about being 4 weeks pregnant.
Week 5Though the embryo is only about the size of a grain of sand, the heart is pumping blood, most other organs have begun to develop, and arm and leg buds appear. You may be starting to experience "pregnancy brain." Read more about being 5 weeks pregnant.
Week 7The embryo doubles in size but is still less than a half-inch long. As your pregnancy hormones increase, morning sickness may be worsening. Or, you may be ravenous 24/7. Read more about being 7 weeks pregnant.
Week 8Your doctor may look or listen for the baby's heartbeat with an ultrasound. Once you see or hear it, your miscarriage risk drops to about 2 percent. He'll also give you an official due date—though very few women actually deliver on that day. Read more about being 8 weeks pregnant.
Week 10Your inch-long baby is now called a fetus. While the icky side effects of pregnancy may be starting to abate, your anxiety about having a healthy baby might be increasing. Read more about being 10 weeks pregnant.
Week 11Your cravings may run the gamut from cheeseburgers to chalk (really!). Weird nonfood cravings are known as pica and can reflect a deficiency in your diet. This week, nearly all of the fetus's organs are beginning to function, and genitals begin to take on male or female form. Read more about being 11 weeks pregnant.
Week 12Your uterus has begun to expand outside the protective pelvic bones. It will increase in size by almost 1,000 times by the end of your pregnancy! You may really be starting to show now, especially if it's not your first baby. Read more about being 12 weeks pregnant.
Week 14Your renewed energy (and end to morning sickness) may lull you into thinking you can take on a marathon, but follow this guideline: Work out only so hard that you can carry on a conversation without getting out of breath. Read more about being 14 weeks pregnant.
Week 18Just when you thought you couldn't possibly take any more pee breaks, you do. It's inevitable: As your baby grows, your bladder shrinks (or so it seems). Read more about being 18 weeks pregnant.
Week 19Now that you're feeling better, it's time to spend some quality time with your partner. So have sex! Unless you're having complications, it's safe for most women throughout pregnancy. Read more about being 19 weeks pregnant.
Week 20You're halfway there, which means your uterus has reached your navel! The nesting urge is probably kicking in. Have fun with it, but don't go overboard and exhaust yourself. Read more about being 20 weeks pregnant.
Week 21If you're 35 or older, have chronic high blood pressure or diabetes or are carrying multiples, you are at a higher risk of preeclampsia. It can occur this early, but usually doesn't set in until the third trimester. Read more about being 21 weeks pregnant.
Week 23Your doctor may soon advise you to steer clear of long-distance travel—not because it is unsafe, but because she wants you close by in case you go into labor. Read more about being 23 weeks pregnant.
Week 24If you are 30 or older, have a family history of diabetes, are Hispanic or obese, you are at increased risk for gestational diabetes. It typically has no symptoms. Read more about being 24 weeks pregnant.
Week 26Your to-do list is getting longer while you're getting more tired. Your fetus begins to sleep for longer periods now, often when you do. Its eyes open and are beginning to blink. Read more about being 26 weeks pregnant.
Week 27You may be distressed to see the numbers on the scale creep (OK, jump) up: From here on out, you'll probably be gaining about 1 pound a week. This still only translates to about 300 extra calories a day, though. Read more about being 27 weeks pregnant.
Week 28Welcome to the third trimester! Braxton Hicks ("practice") contractions usually start about now. They feel like an intermittent tightening in your abdomen. Read more about being 28 weeks pregnant.
Week 30You might find yourself increasingly breathless as your growing uterus crowds your diaphragm. It should ease a bit when the baby drops lower in your pelvis later in pregnancy. Read more about being 30 weeks pregnant.
Week 34You may be driving yourself—not to mention your mate—crazy making sure your house is spit-shined and the nursery is fit for a king (or queen). Keep it in perspective: All you really need is a car seat, a place for the baby to sleep, diapers and some basic clothes. Read more about being 34 weeks pregnant.
Week 35There's a good chance your body harbors Group B streptococcus bacteria without your knowing it. If it colonizes in the vagina and is left untreated, it can infect your baby at birth. Read more about being 35 weeks pregnant.
Week 36The baby may drop lower into your pelvis in preparation for delivery. This should make it easier to breathe—yet your pee breaks will become ever more frequent. Read more about being 36 weeks pregnant.
Week 37 Your breasts may be leaking colostrum—your baby's first food. Plus, you may feel so huge and uncomfortable that you're tempted to ask your doctor to induce you early. Read more about being 37 weeks pregnant.
Week 40 If you haven't delivered yet, your OB will monitor you more closely. Some docs will allow women to go two weeks past their due date; most will induce by then. Read more about being 40 weeks pregnant.