This paper studied whether the removal of one ovary affects fertility compared to other abdominal or pelvic procedures in women. 

Infertility affects 7.4% of all US married couples. 5% of these infertility cases are caused by medical treatments like chemotherapy and surgery on women. Conservative surgery on genital organs is performed to treat disease but can still allow women to conceive. Unilateral ovariectomy (removal of one ovary) is regarded as a conservative surgical treatment typically used for women with being ovarian cysts (fluid filled sacs or pockets within or on the surface of the ovary). However, compared to other procedures, its effects on fertility outcome are still unknown.

The authors compared the long term effect of unilateral ovariectomy on fertility with respect to other abdominal or pelvic surgeries .

113 women who were assumed to be fertile and who underwent unilateral ovariectomy (31%), appendectomy (34.5%; removal of appendix) or cholecystectomy (34.5%; removal of gallbladder) were studied. Women eligible for the study did not have diseases affecting fertility and had no treatments that reduced fertility. They also had no previous abdominal or pelvic surgeries and did not use contraception after surgery. At least 10 years after their surgery, information about health and pregnancy outcome was obtained during a gynaecological check-up or telephone interview.

In total, there were 75 successful pregnancies (26 from unilateral ovariectomy, 23 from appendectomy and 26 from cholecystectomy). Overall, 66.3% of patients experienced at least one successful pregnancy. Comparing across the three surgeries, the percentage of patients who had at least one successful pregnancy was 48.5% in unilateral ovariectomy, 41% in appendectomy, and 53.8% in cholecystectomy.

In unilateral ovariectomy patients, 14.2% of patients had 2 successful pregnancies while 5.7% of patients had more than 2 successful pregnancies. In appendectomy, 18% of patients had 2 pregnancies. In cholecystectomy, 12.8% of patients had 2 successful pregnancies. One unilateral ovariectomy patient, one appendectomy patient and 2 cholecystectomy patients used assisted reproductive technology to become pregnant.

There were no pregnancies in patients older than 37 years in unilateral ovariectomy, 32 years in appendectomy and 36 years in cholecystectomy. The percentage of patients who reported at least one miscarriage was 28.5% in unilateral ovariectomy, 28.2% in appendectomy and 30.8% in cholecystectomy.

The authors concluded that there was no significant difference with regards to fertility in patients who had unilateral ovariectomy compared to other abdominal or pelvic surgeries.