Figure 1.

Fetal progesterone concentrations at d75 gestation. (a) Progesterone concentrations from the control ewes (n = 10) and their fetuses (n = 20). (b) Maternal progesterone was increased after the progesterone treatment (C = 10; P = 10). (c) Fetal female controls (n = 10) had higher progesterone concentration than fetal male controls (n = 10). Maternal progesterone administration had no effect on female fetuses (n = 13) but increased male fetal progesterone concentration (n = 7). (d) The difference in progesterone concentration was present in control male and female co-twins (n = 3). The sexually dimorphic effect of maternal progesterone treatment was seen in male/female co-twin pairs (C = 3; P = 3). Box plot whiskers are lowest and highest observed values, box is the upper and lower quartile, with median represented by line in box. Unpaired, two-tailed Student’s t test was used for comparing means of two treatment groups with equal variances accepting P < 0.05 as significant. Maternal progesterone was analysed using unpaired, one-tailed Student’s t test. The effect of progesterone treatment on female and male fetuses was analysed using two-way ANOVA with Tukey post hoc test. Co-twin fetal serum progesterone level between male and female was analysed using a paired two-tailed Student’s t test and between progesterone and control a one-tail unpaired Student’s t test (*P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001).