Pregnancy week by week

Choose any week from 4 to 42 from the menu, or step through them with the previous and next buttons. If you enter your due date, the guide jumps to the week you're in today and shows how far along you are in weeks and days.

Each week shows:

• A size comparison (a lime at 12 weeks, a banana at 20 weeks), plus the trimester.
• Length in inches with millimeters or centimeters in parentheses, labeled crown to rump or head to heel.
• Estimated weight in ounces or pounds with grams, from week 10 on.
• Your baby: what is developing this week.
• Your body: common changes and symptoms, and when to call.
• To-do this week: prenatal visits, screening windows and practical steps for the US system.

Every week also has its own page you can bookmark or share, for example 24 weeks pregnant, with the tests due that week and a full list of weeks. Nothing you enter is saved or sent anywhere.

Week	About the size of	Length	Weight
8	a raspberry	0.6 in (16 mm), crown to rump	–
12	a lime	2.2 in (5.6 cm), crown to rump	2.0 oz (58 g)
16	an avocado	4.7 in (12 cm), crown to rump	5.1 oz (144 g)
20	a banana	10.2 in (26 cm), head to heel	11.6 oz (330 g)
24	a 12-inch ruler	11.8 in (30 cm)	1.5 lb (665 g)
28	a butternut squash	15.0 in (38 cm)	2.6 lb (1,190 g)
32	a bunch of celery	16.5 in (42 cm)	4.2 lb (1,900 g)
36	a leek	18.5 in (47 cm)	6.1 lb (2,750 g)
40	a pumpkin	20.1 in (51 cm)	8.0 lb (3,620 g)

Why length jumps at 20 weeks: until week 19 your baby is measured from the top of the head to the bottom, because the legs are curled up. From week 20 the guide switches to head-to-heel length. So week 19 reads about 5.9 in (15 cm) and week 20 about 10.2 in (26 cm), even though your baby didn't double in a week.

These are rounded medians. Healthy babies vary a lot, and your provider tracks your baby's growth against your own scans and measurements.

Weeks	Length	Weight
4–8	NHS week-by-week guide	–
9–14	INTERGROWTH-21st crown-rump length standard (median)	Hadlock 1991, 50th percentile (weeks 10–13)
15–19	NHS, head to bottom	WHO fetal growth charts 2017, 50th percentile
20–40	NHS, head to heel	WHO fetal growth charts 2017, 50th percentile
41–42	no weekly figure	no weekly figure (NHS: the average baby is around 3 to 4 kg, about 6.6 to 8.8 lb, at 41 weeks)

The US-specific to-dos follow ACOG patient guidance on routine tests and genetic screening, CDC vaccine recommendations and the Office on Women's Health visit schedule.

Weeks are counted from the first day of your last period, not from conception. That means you are already about 2 weeks along when you conceive, and a home test usually turns positive around week 4. Week 12 here means 12 weeks 0 days through 12 weeks 6 days.

Trimester	Weeks (ACOG)	Often noticed
First	up to 13+6	Tiredness, nausea that usually starts before 9 weeks and eases by about 14 weeks for most people
Second	14+0 to 27+6	More energy for many; first movements, often between 16 and 24 weeks
Third	28+0 to birth	More discomfort, trouble sleeping, weekly visits near the end

Don't know your week? The pregnancy week calculator works it out from your last period, an ultrasound or an IVF transfer. For the full schedule of tests, see the prenatal visit schedule.

Don't wait for your next appointment. Call your OB-GYN or midwife, or go to labor and delivery, if you have:

• vaginal bleeding or fluid leaking from the vagina
• your baby moving less than usual, or a change in their usual pattern (you don't need to count to a set number of kicks; get to know what is normal for your baby)
• a severe headache, vision changes such as blurring or spots, pain under your ribs, or sudden swelling of the face or hands
• severe or constant belly pain
• a fever, severe vomiting, or itching that is intense, especially on the palms and soles

For chest pain, trouble breathing or heavy bleeding, call 911. This guide is informational and is not a substitute for medical advice from your provider.