Guide to Female Hormones: When you’re trying to conceive, knowing how your menstrual cycle works can help you achieve your goal. Of course, few of us can remember all the details about our cycle, even if we’ve learned them before. Whether or not you’re trying to conceive at the moment, here’s an overview to help chart the course when it is time:
A normal, “non-pregnant” menstrual cycle can range anywhere between 25 to 35 days. The actual length of the cycle varies among women, and you can also experience different cycle lengths from time to time.
How long is your menstrual cycle and how does that effect you when you’re trying to conceive? If you’re unsure how to answer this question, you’re not alone. Day 1 of your menstrual cycle is the first day of your menstrual period, or the first day of full flow. The length of your menstrual cycle is the number of days between Day 1 of one cycle to Day 1 of the next cycle. There are specific days in your cycle when a woman is more fertile and has a higher chance of getting pregnant.
Your menstrual cycle is controlled by two hormones released by your brain’s pituitary gland--follicle stimulating hormone (FSH) and luteinizing hormone (LH)--and two hormones released by your ovaries -- estrogen and progesterone. Both hormones play a part in helping conception.
Growing the Follicles - Day 1 - "Hard to Conceive": On Day 1, the levels of all hormones are low. This initial phase of the menstrual cycle is also called the follicular phase, because follicles (each housing an egg) are growing and developing in the ovary. This is when you are "least fertile".
The growth of ovarian follicles is supported by FSH. As the follicles grow and mature, they release estrogen. So, the level of both FSH and estrogen start to rise. The increase in estrogen also causes the uterine lining to grow rapidly and thicken in preparation for a fertilized embryo to implant.
Ovulation: If your menstrual cycle is 28 days long, around Day 12 to13, your high blood estrogen level will kick in a surge of LH and help the largest follicle mature, which in turn, leads to the release of an egg. Typically, Day 12 to 13 of the menstrual cycle yields the greatest chance for conception. Also known as “ovulation,” this is the monthly event that you would closely monitoring when you are trying to conceive.
Trying to get Pregnant – Tip #1: Ovulation prediction kits (OPKs) detect the LH surge in your urine 24 to 36 hours before ovulation, because having sex with your partner during this time gives you the best chance to conceive.
Preparing the Uterus – “Luteal Phase” : As the egg is released, the follicle makes and releases progesterone, the master hormone required for implantation and getting pregnant. Progesterone is essential to prepare the uterine lining for embryo implantation and early pregnancy. The second part of your menstrual cycle between ovulation and your next period is called the “luteal phase”, which is around 14 days for women with 28-day cycles and can be characterized as the “X” fertile period of a woman’s menstrual cycle.
Trying to get Pregnant – Tip #2: The luteal phase tends to get shorter (fewer days) as you get older, which can make it more challenging for a woman to get pregnant. Some fertility patients may get a diagnosis of luteal phase defect in their menstrual cycle. It can refer to a variety of scenarios: Not enough progesterone is released; the uterine lining is not well-prepped; or the uterine lining is somehow not able to support an early pregnancy. Unfortunately, tests that identify each of these scenarios are not precise. Also, a woman can be found to have luteal phase defect in some of her menstrual cycles, while other cycles may be normal. So the diagnosis may be inexact. If your doctor is concerned that luteal phase defect is affecting your fertility, he/she may prescribe progesterone as luteal phase support-- starting on the third day after your LH surge of a period.
Back to the Beginning: If the egg is not fertilized, or the fertilized egg does not implant in this cycle, the woman was unable to conceive during this menstrual cycle and progesterone levels start to fall. By Day 26 to 28, all the hormones are back to their low levels. Without the support of the hormones, the uterine lining starts to shed. And the menstrual cycle returns to Day 1.
Trying to get Pregnant –Tip #3: If a woman does conceive during her menstrual cycle, the embryo implants to the uterine lining and the growing embryo will begin to make the pregnancy hormone, beta hCG (human chorionic gonadotropin). hCG stimulates the ovaries to continue to produce progesterone and support the pregnancy. The embryo is already trying to take care of itself.