Many females get myopic during pregnancy. That is why we do not recommend LASIK for pregnant females unless their prescription is stable.
In my experience in most, but not all female, the myopia regresses after cessation of breast feeding.
Dr. O.
It's not unusual to have a change in refraction due to the hormonal influences of pregnancy. Just google key words "pregnancy and myopia" to find information. Vision tends to stabilize 6 months after birth.