How Big Is Your Baby This Week? This Fetal Development Guide Will Tell You

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We want our babies to be sweet and healthy, so maybe that’s why we like to compare their fetal development to fruit (and the occasional veggie). Get to know your baby bump better with this weekly guide to baby’s size and monthly check-in on baby’s amazing physical growth while in the womb. And keep in mind, healthy babies come in all shapes and sizes, so guides like this are just for fun.

photo: Public Domain Pictures via Pixabay

First Trimester

Whether your bump is bumping or nonexistent, your baby is experiencing a lot of growth during this first trimester. The brain, nerves and spinal cord start forming, as do those cute baby fingers and toes, and baby’s heart begins to beat (you’ll hear it at your prenatal check-ups!).

Let’s see how big baby is, starting at week 4. Why week 4? Because conception is usually tracked from the first day of your last period, so you’re generally not pregnant until week 3, when fertilization occurs.

photo: Skitterphotos via Pixabay

4 weeks—poppy seed
At this stage, baby is a blastocyst, a rapidly dividing ball of cells that will become the embryo and placenta.

5 weeks—sesame seed

6 weeks—pomegranate seed

7 weeks—blueberry

photo: couleur via Pixabay

8 weeks—raspberry
Your baby’s nose, upper lip and taste buds are forming, and the tail is nearly gone.

9 weeks—cherry

10 weeks—kumquat

11 weeks—fig

photo: Tesa Photography via Pixabay

12 weeks—lime
This is the week when fingernails generally form and baby’s face begins to look more human, with eyes and ears moving into their typical spots and a clear profile you’ll soon see during your ultrasounds.

13 weeks—small lemon

Second Trimester

In this trimester, your baby will likely begin to move and hear, along with other exciting developments.

14 weeks—peach

15 weeks—apple

photo: Ponce Photography via Pixabay

16 weeks—avocado
By the four-month mark of pregnancy, babies can usually make a fist and suck their thumb. They can move their eyes and have begun to develop toenails.

17 weeks—pear

18 weeks—bell pepper

19 weeks—mango

photo: StockSnap via Pixabay

20 weeks—banana (in length)
You’ve hit the halfway point on your pregnancy, and you may be able to feel baby’s fluttery movements! Your baby is now regularly sleeping and waking and is drinking several ounces of amniotic fluid a day.

21 weeks—carrot (in length)

22 weeks—papaya

23 weeks—eggplant

photo: Couleur via Pixabay

24 weeks—ear of corn (in length)
Babies are skinny and wrinkly at this stage but will start to plump up soon. Their skin is now starting to become more opaque (it had been translucent).

25 weeks—rutabaga

26 weeks—zucchini

27 weeks—cauliflower

photo: Hans via Pixabay

28 weeks—kabocha squash
Baby can now bat their eyes at you through partially open eyelids, covered in eyelashes. Babies start to develop more fat at this stage and are practicing breathing, both in preparation for life outside the womb.

Third Trimester

In the final trimester in the womb, your baby should increase their weight significantly, so you’re likely to feel and see more of their movements.

29 weeks—butternut squash

30 weeks—cabbage

31 weeks—coconut

photo: Dezalb via Pixabay 

32 weeks—Napa cabbage
Baby is starting to sprout hair on their head and losing the soft hair that has covered their body (known as lanugo). Their formerly wrinkly skin is smoothing out.

33 weeks—pineapple

34 weeks—cantaloupe

35 weeks—honeydew melon

photo: BlackRiv via Pixabay

36 weeks—romaine lettuce
Baby’s liver and kidneys should now be working, and baby has grown so much, they take up most of the amniotic sac. You will likely feel lots of stretches and rolling movements.

37 weeks—Swiss chard (in length)

38 weeks—rhubarb stalk (in length)

39 weeks—small pumpkin

photo: FruitnMore via Pixabay

40-42 weeks—watermelon

It’s go time! At this point, baby’s lungs are continuing to develop so they can give you that big, healthy cry at birth.

Eva Ingvarson Cerise


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