It's called the fontanel if I'm not wrong. They look fragile but they are actually very well-protected by a strong membrane. The bones in baby’s skull will build up enough minerals to completely fuse together and those gaps will close. The back fontanel will close first; generally when baby is between 2 to 4 months old. The front will continue to grow well into the second year. It differs from baby to baby though. But the membrane protecting it us pretty sturdy so I reckon there's nothing to worry about.
If it is bulging, I would think that it would be good to check with the doctor. The soft spot at the back would usually close by 4 months. Soft spot usually look kind of flat or a little sunken. Perhaps you can check with your doctor at the next checkup.
Promo terbesar expert care sudah dimulai, diskon hingga Rp.100.000 sedang berlangsung di shopee, ada juga voucher diskon 100% alias gratis bagi bunda yang beruntung. Buruan cek di https://shope.ee/9UfEMMqqTg (id-15709)
Back of the head? Overall. Baby skull is still very soft. It will only harden once they turn 2 year old
back of the head i don't know. but if you meant on the top it's the fontanel.