Pregnancy week by week
Pick a week to see your baby's average size as a fruit or vegetable, the length and weight, what's developing, how you may feel and one practical tip.
Pregnancy is counted in 40 weeks from the first day of your last period, in three trimesters. Each page here gives the average size, length and weight for that week, from published growth charts.
These are averages. Every baby grows at their own pace.
First trimester
Week 4a poppy seed
Week 5a sesame seed
Week 6a lentil
Week 7a blueberry
Week 8a raspberry
Week 9a cherry
Week 10a strawberry
Week 11a fig
Week 12a lime
Week 13a peachSecond trimester
Week 14a lemon
Week 15an apple
Week 16an avocado
Week 17a pear
Week 18a bell pepper
Week 19a mango
Week 20a banana
Week 21a pomegranate
Week 22a papaya
Week 23a grapefruitWeek 24an ear of corn
Week 25an aubergine
Week 26a coconut
Week 27a cauliflowerThird trimester
Week 28
Week 29
Week 30
Week 31
Week 32
Week 33
Week 34
Week 35
Week 36
Week 37
Week 38
Week 39
Week 40- NHS: Your pregnancy week by week
- ACOG: How your fetus grows during pregnancy
- Hadlock FP et al. Radiology 1991 (weights); Robinson HP, Fleming JE. Br J Obstet Gynaecol 1975 (early lengths)
Questions
How are pregnancy weeks counted?
From the first day of your last period. Week 4 is about two weeks after conception, and the due date falls at 40 weeks.
Where do the sizes come from?
From published fetal growth charts (Hadlock for weights from week 10, Robinson and Fleming for early lengths), cross-checked against the NHS. They are averages, so your own scans may differ.
Which trimester am I in?
The first trimester runs to the end of week 13, the second from week 14 to week 27, and the third from week 28 until birth.
Start with today
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