13 Weeks Pregnant - End Of First Trimester

The end of the first trimester

Your baby's kidneys are now producing urine and they are practicing making breathing movements even though they are getting the oxygen they need from the placenta. Their head is about a third the size of their body. Their first hair is now appearing on their head and eyebrow hair is developing.

Your baby's development

Baby as big as a peach

Length 8 cm Weight 23 g

Your baby's development

Your baby measures around 8cm from the top of their head to their bottom.

In the following weeks your baby’s proportions will start to resemble a newborn. At the moment their head is quite large and makes up a third of their body size.

When awake, they are very active; stretching, kicking, turning, reaching and grasping with their tiny fingers. Internally, their kidneys are starting to work by sending urine to the bladder.

Fine downy hair begins to develop on your baby's skin. Their sucking and swallowing reflexes are becoming stronger and your baby’s skeleton and skeletal muscles now hold them more erect.

Your body

Although your baby’s arrival is months away, your breasts and milk ducts are already preparing for breast feeding. They'll soon start producing thin yellow liquid called colostrum. This is packed with nutrients and will be the first milk that nourishes your baby before your regular milk starts to flow.

Your breasts may feel lumpy as they change and grow in size however, the tenderness of the first trimester is likely to diminish.


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Please Note: These pregnancy week-by-week articles, are meant to give you a general sense of the growth and development going on within you. However, it’s important to remember that every baby develops differently, even during pregnancy.

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