Increased estrogen levels cause the endometrium, or uterine lining, to thicken. This is similar to growing a dense, green grass, except you're growing a nutrient-rich uterine lining in preparation for receiving a fertilized egg instead of a lawn. The fertilizer is estrogen.
This is considered the Follicular phase (pre-ovulation), the phase were you can be highly pregnant (if you're aiming to get a baby).
Explanation:
There are increasing amounts of estrogen that stimulate a thickening of the lining of the uterus, known as the endometrium. This can be thought of as growing a thick, lush lawn, but instead of a lawn, you’re growing a nutrient-rich uterine lining in preparation to receive a fertilized egg. Estrogen is the fertilizer. The thickened endometrium or “bed of grass” is essential for a fertilized egg (egg + sperm = embryo) to attach or implant into the uterine lining. This is an essential process that occurs in preparation for an embryo (fertilized egg that will become a fetus) to attach or implant itself in the uterus and continue its development.
