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How big is my baby during pregnancy?

Your baby is constantly growing and developing throughout your pregnancy. This chart will give you a general idea of how big your baby is at different stages during your pregnancy.

This chart is for information purposes only. Your midwife will give you the most accurate measurement of your baby. There are two ways to measure the size of your baby:

By measuring the size of your bump, this is known as measuring the fundal height. They will measure from your pubic bone to the top of your uterus, to make sure your baby’s growth is on track for your stage of pregnancy. .
Your baby’s size can also be measured when you go for an ultrasound scan, such as your 12 week dating scan or a growth scan if your midwife thinks it’s necessary.

If you have any questions about the size of your baby and stage of pregnancy, please speak to your community midwife. We cannot give advice on individual pregnancies, particularly as we do not have access to your maternity notes.

We would love to support you with your antenatal classes though. We have options to suit all budgets and locations UK-wide. Click on the links below for more information:

Pregnancy: baby growth chart

PREGNANCY / WEEK	BABY’S LENGTH / CM	BABY’S WEIGHT / G	BABY’S LENGTH / IN	BABY’S WEIGHT / OZ
Week 4	0.036 – 0.10 cm	–	up to 0.04 in	< 0.04 oz
Week 5	0.13 cm	–	0.05 n	< 0.04 oz
Week 6	0.32 cm	–	0.13 in	< 0.04 oz
Week 7	1.27 cm	–	0.5 in	< 0.04 oz
From 8 – 19 weeks your baby’s measurement is from crown to rump
Week 8	1.60 cm	1 g	0.63 in	0.04 oz
Week 9	2.30 cm	2 g	1.22 in	0.07 oz
Week 10	3.10 cm	4 g	1.22 in	0.14 oz
Week 11	4.10 cm	7 g	1.61 in	0.25 oz
Week 12	5.40 cm	14 g	2.13 in	0.49 oz
Week 13	7.40 cm	23 g	2.91 in	0.81 oz
Week 14	8.70 cm	43 g	3.42 in	1.52 oz
Week 15	10.10 cm	70 g	3.98 in	2.47 oz
Week 16	11.16 cm	100 g	4.57 in	3.53 oz
Week 17	13.00 cm	140 g	5.12 in	4.94 oz
Week 18	14.20 cm	190 g	5.59 in	6.70 oz
Week 19	15.30 cm	240 g	6.02 in	8.47 oz
From 20 weeks your baby’s measurement is from crown to heel
Week 20	25.60 cm	300 g	10.08 in	10.58 oz
Week 21	26.70 cm	360 g	10.51 in	12.70 oz
Week 22	27.80 cm	430 g	10.94 in	15.17 oz
Week 23	28.90 cm	501 g	11.38 in	1.10 lb
Week 24	30.00 cm	600 g	11.81 in	1.32 lb
Week 25	34.60 cm	660 g	13.62 in	1.46 lb
Week 26	35.60 cm	760 g	14.02 in	1.68 lb
Week 27	36.60 cm	875 g	14.41 in	1.93 lb
Week 28	37.60 cm	1005 g	14.80 in	2.22 lb
Week 29	38.60 cm	1153 g	15.20 in	2.54 lb
Week 30	39.90 cm	1319 g	15.71 in	2.91 lb
Week 31	41.10 cm	1502 g	16.18 in	3.31 lb
Week 32	42.40 cm	1702 g	16.69 in	3.75 lb
Week 33	43.70 cm	1918 g	17.20 in	4.23 lb
Week 34	45.00 cm	2146 g	17.72 in	4.73 lb
Week 35	46.20 cm	2383 g	18.19 in	5.25 lb
Week 36	47.40 cm	2622 g	18.66 in	5.78 lb
Week 37	48.60 cm	2859 g	19.13 in	6.30 lb
Week 38	49.80 cm	3083 g	19.61 in	6.80 lb
Week 39	50.70 cm	3288 g	19.96 in	7.25 lb
Week 40	51.20 cm	3462 g	20.16 in	7.63 lb

Digital and group antenatal courses

We have a number of different antenatal courses available to help you prepare for labour, birth and your baby’s arrival. The courses are practical and evidence-based. They’re taught by practising midwives and will give you the knowledge and tools to approach birth and parenting with confidence. Find out more via the links below:

£45