17 weeks pregnant

Major developments and increased movement in week 17 of pregnancy

Now weighing roughly 150g (just over 5oz) and measuring around 13cm from crown to rump, your baby’s body is growing bigger and becoming more in proportion with their head. 

Their hair, eyebrows and eyelashes are growing longer, and they can also open and close their mouth and move their eyes, which are still shut. Although your baby is also putting on a bit of weight, they still don’t have much fat but their special fat-storing ‘adipose tissue’ is beginning to form.

Internally, your baby’s major body systems are becoming established. By the 17th week of pregnancy, their heart may be beating around 140–150 bpm – much faster than the average resting adult, whose bpm ranges from 60–100. Their respiratory system is developing too, and their chest will rise and fall as they start practising how to breathe.

The future benefits of vitamin D for your baby

Vitamin D forms an important part of a healthy pregnancy diet. It regulates the levels of calcium and phosphate in your body and supports the growth and development of your baby’s bones. Vitamin D is especially important for normal bone development, as a deficiency can cause your baby’s bones to soften, which can lead to rickets, in extreme cases. Furthermore, the vitamin D you consume during your pregnancy will also help build up your baby’s personal store, which they will rely on in the first few months of life.

The most efficient way to get vitamin D is through exposure to the UVB rays in sunlight. However, in Ireland we only get around 6 months of effective sunlight each year during the summer. This means that getting enough vitamin D through skin exposure to sun alone may not be enough to support your baby during pregnancy.

You can increase your vitamin D intake by making sure you eat certain foods, but the best way to make sure you’re getting enough is to take it as a supplement. It’s recommended that you get 10 micrograms of vitamin D each day during pregnancy.