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. 2018 May 30;596(23):5535–5569. doi: 10.1113/JP274948

Figure 3. Circulating progesterone remains elevated throughout pregnancy in guinea pigs and humans.

Figure 3

Circulating progesterone (A) and corpus luteum (CL)‐dependence of pregnancy maintenance (B) reflect species differences in placental progesterone production throughout pregnancy. Bars indicate main source of circulating progesterone (white: CL, shaded: placenta). Ticks indicate that pregnancy can be maintained after removal of the ovary or CL, crosses indicate that either the CL or exogenous progesterone is required to maintain pregnancy. A is reproduced from Mitchell & Taggart (2009 with permission. Data in B are from Csapo & Pulkkinen (1978), Csapo et al. (1981), Al‐Gubory et al. (2000) and Bazer (2015).