Dear student,
Two changes that occur during menstruation and pregnancy includes :
1. Changes in the hormonal levels inside the body. During menstruation, the level of all the hormones like estrogen,, LH, progesterone lowers down. Similarly, in case of pregnancy, the level of hCG increases during 4th to 20th week and progesterone and estrogens increases during 26th to 40th week of pregnancy.
2. During menstruation, since the uterus sheds its lining, their is bloating of the abdomen and cramps during that period.
In pregnancy, since the uterus carries the baby, therefore with each month the uterus enlarges as the baby grows till the ninth month. There is increase in weight of the mother.
Regards.