A Week By Week Guide To Pregnancy

In general, your pregnancy will last an average of 40 weeks. First time mothers usually deliver around 41 weeks, while mothers who are carrying multiples generally deliver before 40 weeks. Here’s what you can expect during each:

Weeks 1-2: When using the gestational age method, week one begins when your period begins. Around day 14, you will ovulate.
Weeks 3-4: Conception takes place as the egg is fertilized – usually in the fallopian tubes – and travels to the uterus, where it implants into the uterine lining. You may experience some implantation bleeding or some mild cramping during this time, although your early pregnancy symptoms will be hard to distinguish from premenstrual symptoms, such as fatigue, mood swings and breast tenderness.
Week 5: The fertilized egg is now an embryo and the major systems are starting to develop. The first systems to develop are the heart and circulatory system.

Week 6: Your baby's heart begins to beat, while most other organs are starting to be formed. Arm and leg buds form, and the umbilical cord develops. You can also see where the baby's eyes and ears will be. If you haven't had morning sickness before, this is usually when it hits.
Week 7: The arms and legs are continuing to develop, as are the brain, eyes, intestines and other organs. The intestines will initially bulge into the umbilical cord during this week.
Week 8: Tooth buds begin to form in the baby's gums, and you can see the beginnings of fingers and toes. On an ultrasound, you can see the baby's heart beating. You may have started to noticed a difference around your waistline at this time, as your uterus is now about the size of an orange.
Week 9: There’s now room for the growing intestines to move out of the umbilical cord and into the baby's abdomen. The baby's bones and cartilage also begin to form. You may experience some heartburn and indigestion at this stage and it may be time for new bras with larger cups.
Week 10: The baby begins to move around, although these movements can’t yet be felt. Fingers and toes are developed, and joints at the shoulder elbow, wrist, knee and ankle are formed.

Week 11: This week, your embryo officially becomes a fetus. You may not even look pregnant yet, but the most critical stages of development are already complete. During this week, your baby will double in length, from one inch to two inches. During weeks 11 and 12, the placenta will begin to function and blood will begin to circulate through the umbilical cord. In most women this coincides with a decrease or end to morning sickness. From the size of a pear, your uterus has grown to the size of a grapefruit and you may begin to experience round ligament pain.
Week 12: Nearly all organs are finished forming. Nails and hair begin to grow and genitals differentiate. The kidneys begin to function and amniotic fluid begins to accumulate. As your uterus grows, it will shift forward off your bladder, so urinary frequency will lessen.
Week 13: Here, the first trimester ends and the baby begins to look more like a miniature person. You may still feel tired, but most early pregnancy symptoms will begin to disappear now.
Week 14: The baby is about 3 and one-half inches long and weighs about 2 ounces. Your baby is being fully nourished by the placenta now. Usually, the baby's heartbeat can be detected via Doppler at this stage, and the baby begins to “breathe” in amniotic fluid. The baby's hands can move and you may be noticing some constipation and more prominent veins in your breasts.
Week 15: The baby is now covered in soft, downy hair called lanugo, which will protect her skin until later in pregnancy. At this point, your uterus has grown enough that you can probably feel it just below your navel, and you may have begun to show.
Week 16: You may begin to feel the baby move at this point. Some women tend to experience nasal congestion or nose bleeds, and round ligament pain may continue.
Week 17: Your baby is growing rapidly and can now swallow, blink and suck her fingers. By this time, you’ve probably gained between 5 and 10 pounds of pregnancy weight.
Week 18: The baby weighs about 8 ounces now, and you may be able to see your tummy move from the outside when baby moves or has hiccups. Gender can sometimes be determined via ultrasound at this stage.
Week 19: Vernix, which protects the baby's skin, forms. You may also notice skin changes of your own, including dryness or pigment changes.
Week 20: You're at the halfway point. The baby's sleep and waking schedule is much like that of a newborn. Your uterus may press on your belly button, causing it to become an “outtie,” and you may develop a linea nigra.

Week 21: The baby continues to grow, though not as rapidly. You’re probably beginning to show if you haven't been already, and you may be experiencing some swelling in your feet and ankles. You’ve probably now gained about 10 to 15 pounds.
Week 22: Your baby's brain continues to grow rapidly at this stage, and the baby now weighs about one pound. You may begin to experience some back pain around this time.
Week 23: Bones develop in baby's middle ear. This is a good time to learn about childbirth classes and enroll in the ones that interest you.
Week 24: The baby begins to fill out. Your doctor may schedule you for an ultrasound or glucose tolerance test at this point.
Week 25: The baby's spine and pulmonary circulatory system begin to form. Your uterus is now about the size of a soccer ball – and you can definitely tell!
Week 26: Your baby now weighs about 2 pounds. Air sacs in the lungs are forming and brain wave activity begins. You may also begin to experience Braxton Hicks contractions around now.
Week 27: The baby's brain continues growing rapidly and the retinas begin to form. You may begin to experience difficulty breathing, as your uterus is now pressing against your diaphragm.
Week 28: The third trimester begins. The baby now weighs about 2 pounds and can recognize your voice. At this point, you’ve probably gained between 17 and 24 pounds. During the final trimester, you may experience leg cramps, itchy skin, hemorrhoids and increased swelling in your feet and legs. You’ll probably also begin seeing your health care provider every other week, instead of monthly.
Week 29: The primitive breathing functions are now controlled by baby's brain. The baby is becoming sensitive to sound and light, and can taste the amniotic fluid. This is a good time to start working on your birth plan.
Week 30: Your baby now weighs about 3 pounds. The lanugo begins to disappear and you may be having trouble finding comfortable positions for sleeping.

Week 31: Your baby's brain is continuing to develop. All of the major organs – except the lungs – are fully developed.
Week 32: Your baby now weighs 4 pounds. You may be experiencing increasing heartburn and constipation, along with other pregnancy discomforts at this point.
Week 33: The amount of amniotic fluid you have now will remain fairly constant until delivery. Brain growth means baby's head is about an inch larger, and you’ll gain about a pound a week for the rest of your pregnancy.
Week 34: The baby's eyes are now open when awake and closed when sleeping. Your baby begins to develop some immunity, and Braxton Hicks contractions become more frequent.
Week 35: Your baby weighs about 5 and one-half pounds and takes up most of the space in your uterus. Your cervix may begin to efface or dilate in preparation for the upcoming delivery.
Week 36: The baby may move into birthing position and drop into the birth canal. You’ll begin seeing your health care provider weekly at this point and should be aware of signs of premature labor.
Week 37: Your baby weighs about 6 and one-half pounds now and will continue to gain about one-half pound per week. You may notice increased vaginal discharge and you may begin to breathe easier as baby drops into the birth canal. Bu this point, you should be preregistered at the hospital and have your delivery bags packed and waiting for you.
Week 38: The baby continues to gain weight and Braxton Hicks contractions occur more frequently.
Week 39: The baby probably weighs over 7 pounds by this point. Surfactant is preparing the lungs for breathing after birth and you’re probably urinating frequently as your uterus presses on your bladder.
Week 40: Congratulations, you’re at term! Your baby could come at any time now – some health care providers schedule even inductions at this point.
Week 41: Most first time mothers deliver this week. If you haven’t yet delivered, your health care provider may schedule tests to make sure everything is alright with your baby.
Week 42-45: If your pregnancy goes this long, your health care provider will likely schedule tests to make sure your baby is fine, and may schedule an induction or Caesarean section delivery.