I have a left ovarian cyst of 11cm.i am 10wks pregnant now and my ob tells me i have to have surgery at 16-20wks.will this surgery harm my baby?

Probably not: A cyst that size requires surgery because it can twist on itself and therein the blood supply to the ovary can be cut off and the ovarian tissue will die. This will also result in severe pain. Your OB is right to wait until the second trimester- this is the safest time in the pregnancy to have the surgery done.

See below: Any abdominal surgery on a pregnant patient could potentially harm the child by causing premature contractions or spontaneous abortion. The chances of this happening is very small, and you will be monitored closely during the immediate post-operative period. The agents used by anesthesia will not affect the development of the child at this stage of your pregnancy.