PTH and ovarian cancer: However, tumor markers should be used with caution in the diagnosis of ovarian cancer during pregnancy.[7] During normal pregnancy, especially in the first and last trimester, decidua and granulosa cells produce CA125, reducing its diagnostic value for ovarian cancer.[8] In the present case, the 21-year-old patient was in the last trimester of pregnancy; she had a slightly elevated level of PTH and normal serum calcium levels at diagnosis.