Curious about my baby in tummy if she /he's normal,what is the best way to know if your baby is ok

#pregnancy im a bit curious about the baby in a tummy,how i find out if my baby is normal like their siblings.because im afraid if i saw somebody giving birth to her child with a physical problem.like for example her baby has a ceased on their head or no ears.sometimes bingot.what is the sign of unhealthy baby in a tummy.i know that ultrasound can detect what is the problem of a baby.but some parents they dont afford to pay the 3d ultrasound its because its too.expensive i hope someone can answer my over thinking question in my head.