What do the moon and sun have in common

They are locked together in stable orbits due to gravity - All have gravity -  All of them are in the Milky Way -  The Moon orbits the Earth, the Earth orbits the Sun - Because they appear to be the same size in the sky, the Sun, Earth and Moon work together to create eclipses - Earth depends on both the Sun and the moon for life as humans know it to exist.

Explanation:

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.