The best time to evaluate the fetal anatomy by ultrasound is between 17-19 weeks. This is the best time to see if it is a boy or a girl. This is also the best time to see that everything is developing normally.
The ultrasound at 17-19 is referred to as the anatomy screening ultrasound. During this ultrasound there is a long checklist of things that will be evaluated. These include brain structures, facial features including looking for cleft lip and cleft palate, heart structures, baby’s stomach, bladder, kidneys, gender, arms, legs, fingers, and toes. The umbilical chord will be checked for the correct number of blood vessels. The amount of amniotic fluid will be measured. The placenta will be checked for development and position. The mother’s cervix, uterus, and ovaries will also be checked at this time.
Sometimes all of the structures cannot be seen at the same time due to the baby’s position. If this is the case, you may be asked to come back on another day to look again. This does not mean that anything is wrong with the baby, just that some of the things on the checklist could not be viewed.
The best time to see if the baby is a boy or girl is between 17-19 weeks. This is when the baby is big enough to see between the legs but not so big as to obscure the view. It is possible to see the gender of the baby as early as 15 weeks (in some cases 14), but the best views coma a few weeks later.