Pregnancy week by week

Pick a week to see your baby’s size and development, what’s happening to your body, and what checkups are coming up.

First trimester Weeks 1–13

From conception to a fully formed, tiny fetus. The most rapid change of the whole pregnancy.

  1. Prenatal development at week 1 Week 1A new cycle begins
  2. Prenatal development at week 2 Week 2Ovulation — and maybe conception
  3. Prenatal development at week 3 Week 3A ball of cells finds its home
  4. Prenatal development at week 4 Week 4Poppy seed
  5. Prenatal development at week 5 Week 5Sesame seed
  6. Prenatal development at week 6 Week 6Lentil
  7. Prenatal development at week 7 Week 7Blueberry
  8. Prenatal development at week 8 Week 8Raspberry
  9. Prenatal development at week 9 Week 9Cherry
  10. Prenatal development at week 10 Week 10Strawberry
  11. Prenatal development at week 11 Week 11Fig
  12. Prenatal development at week 12 Week 12Lime
  13. Prenatal development at week 13 Week 13Lemon

Second trimester Weeks 14–27

Growth, movement and senses. Often the most comfortable stretch for parents.

  1. Prenatal development at week 14 Week 14Peach
  2. Prenatal development at week 15 Week 15Apple
  3. Prenatal development at week 16 Week 16Avocado
  4. Prenatal development at week 17 Week 17Pear
  5. Prenatal development at week 18 Week 18Bell pepper
  6. Prenatal development at week 19 Week 19Mango
  7. Prenatal development at week 20 Week 20Banana
  8. Prenatal development at week 21 Week 21Carrot
  9. Prenatal development at week 22 Week 22Papaya
  10. Prenatal development at week 23 Week 23Grapefruit
  11. Prenatal development at week 24 Week 24Ear of corn
  12. Prenatal development at week 25 Week 25Cauliflower
  13. Prenatal development at week 26 Week 26Zucchini
  14. Prenatal development at week 27 Week 27Head of lettuce

Third trimester Weeks 28–40

Weight gain, brain and lung maturation, and getting into position for birth.

  1. Prenatal development at week 28 Week 28Eggplant
  2. Prenatal development at week 29 Week 29Butternut squash
  3. Prenatal development at week 30 Week 30Cabbage
  4. Prenatal development at week 31 Week 31Coconut
  5. Prenatal development at week 32 Week 32Napa cabbage
  6. Prenatal development at week 33 Week 33Pineapple
  7. Prenatal development at week 34 Week 34Cantaloupe
  8. Prenatal development at week 35 Week 35Honeydew melon
  9. Prenatal development at week 36 Week 36Papaya (large)
  10. Prenatal development at week 37 Week 37Winter melon
  11. Prenatal development at week 38 Week 38Pumpkin (small)
  12. Prenatal development at week 39 Week 39Mini watermelon
  13. Prenatal development at week 40 Week 40Watermelon
Average baby size by week
WeekSize of aLengthWeight
Week 4Poppy seed≈ 2 mm embryonic disc—
Week 5Sesame seed≈ 2 mm crown to rump< 1 g
Week 6Lentil≈ 6 mm crown to rump< 1 g
Week 7Blueberry≈ 10 mm crown to rump< 1 g
Week 8Raspberry1.6 cm crown to rump1 g
Week 9Cherry2.3 cm crown to rump2 g
Week 10Strawberry3.1 cm crown to rump4 g
Week 11Fig4.1 cm crown to rump7 g
Week 12Lime5.4 cm crown to rump14 g
Week 13Lemon7.4 cm crown to rump23 g
Week 14Peach8.7 cm crown to rump43 g
Week 15Apple10.1 cm crown to rump70 g
Week 16Avocado11.6 cm crown to rump100 g
Week 17Pear13 cm crown to rump140 g
Week 18Bell pepper14.2 cm crown to rump190 g
Week 19Mango15.3 cm crown to rump240 g
Week 20Banana25.6 cm head to heel330 g
Week 21Carrot26.7 cm head to heel398 g
Week 22Papaya27.8 cm head to heel476 g
Week 23Grapefruit28.9 cm head to heel565 g
Week 24Ear of corn30 cm head to heel665 g
Week 25Cauliflower34.6 cm head to heel778 g
Week 26Zucchini35.6 cm head to heel902 g
Week 27Head of lettuce36.6 cm head to heel1.0 kg
Week 28Eggplant37.6 cm head to heel1.2 kg
Week 29Butternut squash38.6 cm head to heel1.4 kg
Week 30Cabbage39.9 cm head to heel1.5 kg
Week 31Coconut41.1 cm head to heel1.7 kg
Week 32Napa cabbage42.4 cm head to heel1.9 kg
Week 33Pineapple43.7 cm head to heel2.1 kg
Week 34Cantaloupe45 cm head to heel2.3 kg
Week 35Honeydew melon46.2 cm head to heel2.5 kg
Week 36Papaya (large)47.4 cm head to heel2.7 kg
Week 37Winter melon48.6 cm head to heel3.0 kg
Week 38Pumpkin (small)49.8 cm head to heel3.2 kg
Week 39Mini watermelon50.7 cm head to heel3.4 kg
Week 40Watermelon51.2 cm head to heel3.6 kg