Estrogen is the hormone that dominates the first part of the menstrual cycle in females, while progesterone tends to dominate the second part, just after ovulation. Both hormones must be kept in balance in order to be able to conceive, which is why there is a negative effect of too little or excessive estrogen on fertility. Having too little of this hormone can cause the uterus lining to be too thin to carry a pregnancy, and can even stop ovulation altogether. Too much estrogen can cause a drop in libido, and may even lead to reproductive issues like PCOS or endometriosis. The effects of estrogen on fertility can also be observed in men, as some exhibit an excessive amount of this hormone.
The first half of the menstrual cycle is controlled by estrogen, which allows the body to ovulate toward the middle of the cycle. If there is not sufficient estrogen, the body will likely not ovulate, or release eggs. A woman can usually tell that she is not ovulating regularly when she does not notice much cervical mucus throughout her cycle, and also stops getting her period every month, which makes it clear that there is a negative effect of insufficient estrogen on fertility. Additionally, she may have hot flashes, night sweats, and headaches. Low estrogen levels are typically caused by being too thin, exercising too much, or having an underlying medical condition that does not allow the release of eggs.
While there is an obvious effect of too little estrogen on fertility, it is also known that too much estrogen can impair fertility, as well. About halfway through the cycle, just after ovulation, the hormone progesterone should take over, and the cycle will either end in pregnancy, or the breakdown of the uterine lining via menstruation. Too much estrogen can lead to too little progesterone, and may also cause medical issues that are not conducive to regular ovulation, such as endometriosis, PCOS, uterine fibroids, and uterine cancer. Additionally, estrogen dominance can reduce libido greatly, usually leading to less intercourse and fewer chances to conceive. Excessive estrogen is typically caused by being overweight, having a poor diet, and experiencing too much stress.
Men have a small amount of estrogen in their bodies, often balanced out by a lot of testosterone. Some men make too much of this hormone, or take it artificially to solve certain medical issues. Unfortunately, there is a negative effect of estrogen on fertility in men, such as low libido and low sperm count. Therefore, it is important to get this problem fixed to make conception likely.