Ovularion ceases during pregnancy, and maturation of new follicles is suspended. The single corpus luteum found in graVidas functions maximally during the irst 6 to 7 weeks of pregnancy--4 ro 5 weeks postovulation. Thereafter, ir contributes relarively linie to progesrcrone production. Surgical removal of the corpus luteum before 7 weeks prompts a rapid fall in matenal serum progesrerone levels and spontaneous abortion (Csapo, 1973). Afrer this time, however, corpus lureum excision ordinarily does nO[ cause abortion.
An extrauterine decidual reaction on and jusr beneath the ovarian surface is common in pregnancy and is usually observed ar cesarean delivery. 1l1ese slighdy elevated clear or red patches bleed easily and may, on irst glance, resemble freshly torn adhesions. Similar decidual reactions arc seen on the uterine serosa and other pelvic, or even extrapelvic, abdominal organs (Bloom. 2010). These areas arise from subcoelomic mesenchyme or eniomcrcioric lesions that have been stimulated by progesterone. They histologically appear similar to progestin-stimulated intrauterine endometrial stroma (Kim. 2015).
The enormous caliber of the ovarian veins viewed at cesarean delivery is starding. Hodgkinson (1953) found that the diametcr of the ovarian vascular pedicle increased during pregnancy from 0.9 em to approximately 2.6 em at term. Again, recall that Aow in a tubular structure increases exponentially as the diameter enlarges.
This protein hormone is secreted by the corpus lureum, the decidua. and the placenta in a pattern similar to that of human chorionic gonadotropin (hCG) (Chap. 5. p. 102). Relaxin is also expressed in brain, hean, and kidney. Ie is mentioned here because its secretion by the corpus lureum appears to aid many maternal physiological adaptations, such as remodeling of reproductive-tract connective tissue to accommodate labor (Conrad. 2013; Vrachnis. 2015). Relaxin also appears importam in initiating augmented renal hemodynamics, lowering serum osmolality, and increasing arterial compliance, which are all associated with normal pregnancy (Conrad. 2014a). Despite its name, serum relaxin levels do nOt contribute to greater peripheral joint laxity or pelvic girdle pain during pregnancy (Aldabe. 2012; Marnach. 2003; V0l1estad. 2012).
These benign ovarian lesions reAect exaggerated physiological follicle stimulation, which is termed hyperreactio luteinalis. These usually bilateral cystic ovaries are moderately to massively enlarged. The reaction is usually linked to markedly elevated serum heG levels. Logically, theca-Iurein CYStS are found frequenrlywith gestational trophoblastic disease (Fig. 20-3. p. 391). They also can develop with the placentomegaly that can accompany diabetes, anti-D alloimmunization, and multi fetal gestation (Malinowski, 2015). Hyperreactio luteinalis is associated with preeclampsia and hyperthyroidism, which may contribure to elevated risks for fetal-growth restriction and preterm birth (Cavorerro. 2014; Lynn. 2013; Mlinowski. 2015). hese cystS also are encountered in women with otherwise uncomplicated pregnancies. In these cases, an exaggerated response of the ovaries to normal levels of circulating heG is suspected (Sarmento Gon,alves. 2015).