Sleeping on your front won't affect how teenage breast development or make them smaller. However, if your breasts are feeling sore you might.
Find out when and how your breasts start to develop during puberty. and signs · Breast cancer and teenage girls · How breasts develop during puberty.
Gynecomastia is a condition in which breast tissue forms in guys, usually due to normal hormonal changes during puberty. Hormones are chemicals produced.