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The most important female hormones and their role in fertility 


13 July 2020

Hormones, both male and female, play a huge role in our reproductive systems. In women particularly they can affect whether or not an egg grows in the ovary and is released, the chances of conception and implantation, the survival of a pregnancy and even the ability to breastfeed after a baby is born.

When couples are having fertility problems, doctors will often test for hormone imbalances. While it can be fiddly and time-consuming to get the balance right, it is usually possible to treat hormone imbalances in both men and women.

Read on to learn about the most important female hormones for fertility, and be sure to talk to your doctor about a possible hormone imbalance if you’re having trouble conceiving. 


Follicle Stimulating Hormone (FSH) 


Follicle Stimulating Hormone, or FSH, is an important hormone for fertility in both men and women. It controls sperm production in men and, similarly, egg development in women. FSH, which is produced by the pituitary gland, stimulates the growth of follicles in the ovary in the first half of the cycle. It should be highest right before a woman ovulates (around week two of her cycle). If the hormone is too low, women could experience irregular ovulation or fail to ovulate all together. Too much of the hormone could indicate that the ovaries are of poor quality. 


Oestrogen 


Follicles release oestrogen as they grow in the ovaries, in turn causing the endometrium (womb lining) to thicken in preparation for pregnancy. As one follicle grows bigger than the rest and prepares for release, there is a surge in oestrogen, which prompts the pituitary gland to produce Luteinizing Hormone (see below). This causes a sudden growth spurt in the biggest follicle, resulting in its release. Oestrogen also promotes the secretion of a mucus inside the uterus that provides an ideal environment for sperm survival. Too little oestrogen and the endometrium may not be thick enough for the egg to implant in the uterus. Too much could decrease the window for implantation.  


Luteinizing Hormone (LH) 


Like FSH, Luteinizing Hormone, or LH, is also produced in the pituitary gland and important for both male and female reproduction cycles. In men, LH stimulates the production of testosterone, which is important for sex drive and sperm count. While the correct levels of FSH prompt follicle growth in women, LH causes the egg to actually be released from the ovary. This usually happens two weeks into a woman’s cycle. If fertilization of the egg subsequently occurs, LH will stimulate the corpus luteum (a mass of cells inside the ovary), which in turn produces progesterone to sustain the pregnancy. Again, LH levels need to be just right. Women with too much are often found to have polycystic ovary syndrome, while those with too little will likely fail to ovulate. You can test for this hormone yourself with at-home ovulation kits, which will tell you exactly when you’re due to ovulate and therefore at your most fertile. 


Progesterone


 If a follicle has formed into a corpus luteum, progesterone will be secreted into a woman’s bloodstream. This helps with implantation and also signals that a fertilized ovary should continue to produce progesterone on its own in order for the pregnancy to survive. If no egg has been fertilized, progesterone levels will drop and mensuration will begin. Low levels of progesterone can lead to problems with fertility and breastfeeding after a child is born. 


 So, there you have it, the most important female hormones for conception and fertility. Keep an eye on this blog for more insights and fertility tips.

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