When analyzing female fertility, hormones are the central players driving the entire process. Hormones are defined as chemical messengers that coordinate different bodily functions, released by glands, organs, and tissues, many of which make up the endocrine system (Cleveland Clinic, 2025). These chemical messengers involved in fertility regulate many functions from the menstrual cycle to ovulation and pregnancy. If you are trying to conceive, or simply want to understand the female reproductive system better, knowing how hormones work together within the body provides helpful insight into female reproductive health.
The first hormone we will focus on is the Follicle-Stimulating Hormone (FSH). FSH is produced by the pituitary gland, which is located at the base of the brain, and plays a crucial role in the menstrual cycle of a woman. At the beginning of a woman’s menstrual cycle, FSH levels start to rise, stimulating the growth of ovarian follicles in the ovary before the release of an egg from a follicle during ovulation (Evewell, 2025). In response to the release of FSH, these follicles begin to mature and start producing another important hormone – oestrogen. The continuously rising levels of oestrogen trigger a surge in luteinising hormone (LH), which leads to the release of a mature egg from the dominant follicle – a process known as ovulation (Evewell, 2025). FSH changes throughout the menstrual cycle is an important indicator of one’s ovarian reserve (the number and quality of eggs in the ovaries). With limited FSH, follicles may not mature properly, which can prevent ovulation and indicate potential issues such as hypothalamic amenorrhea. High FSH levels may indicate a diminished ovarian reserve.
The second crucial hormone which plays two main roles in a woman’s menstrual cycle is Luteinising hormone (LH). Produced by the pituitary gland, LH triggers ovulation and stimulates the production of progesterone in the body in preparation for pregnancy (Evewell, 2025). In the first part of the menstrual cycle, FSH stimulates the growth of the ovarian follicles, and as oestrogen levels rise, a surge in LH is witnessed (Evewell, 2025). The ‘LH surge’ triggers ovulation, where a mature egg is released from the dominant follicle. Following this, the egg travels down the fallopian tube where it may be fertilized by sperm. After ovulation occurs, the remains of the dominant follicle form a structure known as the corpus luteum, which is stimulated by LH to produce progesterone (Evewell, 2025). Progesterone is required for preparing the lining of the uterus for an implantation of a fertilized egg. In the case of pregnancy failing to occur, the corpus luteum breaks down, leading to a decrease in progesterone levels and the beginning of a new menstrual cycle (Evewell, 2025). If LH does not surge, this means no ovulation occurs and hence, no opportunity for fertilization.
The next hormone involved in female fertility is oestrogen. As mentioned above, oestrogen is produced in response to a release in FSH. Primarily produced by the ovaries, oestrogen works to regulate the menstrual cycle, promote the growth of uterine lining, and trigger the release of LH for ovulation (Evewell, 2025). The thickening of the uterine lining is crucial as it creates an environment that is rich in nutrients where a fertilized egg can implant. The rising oestrogen levels aligns with a decrease in FSH production to prevent overproduction of ovarian follicles (Evewell, 2025). After ovulation occurs, a rapid drop in oestrogen levels is seen and then an increase is observed again as oestrogen is produced by the corpus luteum (Evewell, 2025). If a pregnancy does not occur, oestrogen levels decline, causing the uterine lining to shed during menstruation.
Progesterone is produced by the ovaries after ovulation and prepares the uterus for a pregnancy (Evewell, 2025). The corpus luteum, made up of the remains of the dominant follicle, produces progesterone after ovulation, which signals for the body to prepare for a pregnancy. If fertilization fails to occur, progesterone levels decrease, and the uterine lining begins to shed (Evewell, 2025). Along with its role in preparing the uterine lining for the implantation of an embryo, progesterone also helps to prevent the muscles of the uterine from contracting, a process that could dislodge the implanted embryo. Progesterone also helps to prevent the body from rejecting the embryo. The drop in progesterone after failed fertilization helps to regulate the menstrual cycle and inhibit excessive release of FSH (Evewell, 2025). Low progesterone can lead to luteal phase defects, making it harder for the body to support a pregnancy.
Finally, Gonadotropin-Releasing Hormone (GnRH) and Human Chorionic Gonadotropin (hCG) are both important hormones for the menstrual cycle. GnRH is secreted by the hypothalamus and prompts the pituitary gland to release FSH and LH. GnRH is the hormone that sets the fertility cycle in motion, and disruptions in GnRH release, due to stress, extreme weight loss, or health conditions, can lead to irregular or absent menstrual cycles. hCG plays several roles in pregnancy, including pregnancy detection, supporting early pregnancy, stimulating foetal growth, preventing embryo rejection, and development of the placenta (Evewell, 2025). hCG is produced by the placenta after implantation and is the hormone that is detected during a pregnancy test. After implantation, the embryo begins to produce hCG which signals the corpus luteum to continue producing progesterone (Evewell, 2025). hCG plays an important role in fetal development; stimulating the ovaries that produce the essential hormones for fetal development – oestrogen and progesterone (Evewell, 2025).
Understanding how these hormones work and interact within the female body is the first step towards making informed reproductive health decisions. When these hormones are in balance, they support ovulation, fertilization, and the potential of pregnancy to form. When trying to conceive, manage a reproductive health condition such as PCOS, or gain more knowledge on female reproduction, hormone health is the key to understanding.
Professional, C. C. medical. (2025b, April 1). Hormones: What they are, Function & Types. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22464-hormones
Hormones & Fertility: IVF & Fertility Clinic London: The Evewell. Hormones & Fertility | IVF & Fertility Clinic London | The Evewell. (2025, April 9). https://www.evewell.com/support/fertility-hormones/