Pregnancy week by week
Your baby's size, weight and development for every week from 4 to 42, plus the scans and tests that usually happen along the way.
Halfway. Measurements switch to head-to-heel from here, which is why length seems to jump.
The top of your uterus is around your belly button.
Full guide to week 20Baby size by week
| Week | Size of | Length | Weight |
|---|---|---|---|
| Week 4 | a poppy seed | 1 mm | < 1 g |
| Week 5 | a sesame seed | 2 mm | < 1 g |
| Week 6 | a lentil | 4–6 mm | < 1 g |
| Week 7 | a blueberry | 1 cm | < 1 g |
| Week 8 | a raspberry | 1.6 cm | 1 g |
| Week 9 | a green olive | 2.3 cm | 2 g |
| Week 10 | a kumquat | 3.1 cm | 4 g |
| Week 11 | a fig | 4.1 cm | 7 g |
| Week 12 | a lime | 5.4 cm | 14 g |
| Week 13 | a peapod | 7.4 cm | 23 g |
| Week 14 | a lemon | 8.7 cm | 43 g |
| Week 15 | an apple | 10.1 cm | 70 g |
| Week 16 | an avocado | 11.6 cm | 100 g |
| Week 17 | a turnip | 13 cm | 140 g |
| Week 18 | a bell pepper | 14.2 cm | 190 g |
| Week 19 | an heirloom tomato | 15.3 cm | 240 g |
| Week 20 | a banana | 25.6 cm (head to heel) | 300 g |
| Week 21 | a carrot | 26.7 cm | 360 g |
| Week 22 | a spaghetti squash | 27.8 cm | 430 g |
| Week 23 | a large mango | 28.9 cm | 500 g |
| Week 24 | an ear of corn | 30 cm | 600 g |
| Week 25 | a rutabaga | 34.6 cm | 660 g |
| Week 26 | a scallion bunch | 35.6 cm | 760 g |
| Week 27 | a head of cauliflower | 36.6 cm | 875 g |
| Week 28 | an eggplant | 37.6 cm | 1.0 kg |
| Week 29 | a butternut squash | 38.6 cm | 1.15 kg |
| Week 30 | a large cabbage | 39.9 cm | 1.3 kg |
| Week 31 | a coconut | 41.1 cm | 1.5 kg |
| Week 32 | a jicama | 42.4 cm | 1.7 kg |
| Week 33 | a pineapple | 43.7 cm | 1.9 kg |
| Week 34 | a cantaloupe | 45 cm | 2.1 kg |
| Week 35 | a honeydew melon | 46.2 cm | 2.4 kg |
| Week 36 | a head of romaine | 47.4 cm | 2.6 kg |
| Week 37 | a bunch of Swiss chard | 48.6 cm | 2.9 kg |
| Week 38 | a leek | 49.8 cm | 3.1 kg |
| Week 39 | a mini watermelon | 50.7 cm | 3.3 kg |
| Week 40 | a small pumpkin | 51.2 cm | 3.5 kg |
| Week 41 | a jackfruit | 51.7 cm | 3.6 kg |
| Week 42 | a watermelon | 51.9 cm | 3.7 kg |
Sizes: approximate averages from Hadlock fetal growth formulas and ACOG patient education. Crown-rump length to week 19, crown-heel from week 20.
Frequently asked questions
How big is my baby this week?
Find your week in the table: it lists typical length and weight, with a fruit or vegetable for scale. Lengths up to week 19 are crown to rump (head to bottom); from week 20 they are crown to heel, which is why the numbers jump at 20 weeks.
Are these sizes exact?
No. They are averages from fetal growth references such as Hadlock's ultrasound formulas. Healthy babies vary, and by the third trimester the normal range spans several hundred grams either way.
When will I feel the baby move?
Usually between 16 and 24 weeks. People who have been pregnant before often notice flutters earlier. By the third trimester, a change in your baby's usual pattern of movement is a reason to call your maternity unit the same day.