Evaluation of Serum Estrogen Progesterone Ratio in the Three Trimesters of Pregnancy in Wistar Rat

Estrogen and Progesterone are two major hormones of pregnancy. As soon as a spermatozoon fertilizes an ovum, hormonal changes begin in preparation for implantation and subsequent maintenance of pregnancy. The aim of the study was to determine if there are changes in Estrogen/Progesterone ratios (E/P) during pregnancy in different trimesters of pregnancy in Wistar rats. Twenty female Wistar rats were categorized into four different groups of five rats each. Group one (non-pregnant rats) served as the control. Groups two, three and four were pregnant rats in days 5, 12 and 19corresponding to first, second and third trimesters of pregnancy respectively. Blood samples collected from the four groups were subjected to ELISA method for the assay of serum estrogen and progesterone levels. There were statistically significant (p<0.05) increases in progesterone in the second and third trimesters when compared with non-pregnant Wistar rats (5.70±1.35pg). There was a statistically significant increase in estrogen levels in the three trimesters of pregnancy. Also, there was a significant correlation between estrogen and progesterone in the second and third trimester of pregnancy but not in the control and first trimester. The E/P ratio in the control was significantly (p<0.01) higher than that of the second and third trimester but not for the first trimester. Conclusively, the E/P ratios are altered during pregnancy and knowledge of this is relevant in hormone therapy in assisted pregnancy technology.