What Is Female Fertility? How Is it Measured?
“Female fertility” refers to a woman’s ability to conceive a child and carry that pregnancy to term. The female reproductive system is complex, requiring many parts to function properly together, but female fertility can be broken down into three major components:
Hormones like follicle stimulating hormone (FSH), anti-Müllerian hormone (AMH), and luteinizing hormone (LH) are directly involved in the healthy development of eggs in women’s ovaries, as well as their release (ovulation). Reproductive hormones regulate our menstrual cycles, preparing the uterus for possible arrival of an embryo each month and shedding the lining when that doesn’t happen. Other hormones that you might not think are involved in reproduction—thyroid hormones, for instance—also play important roles in female fertility.
The hormonal aspects of female fertility can be easily measured via blood tests. What’s My Fertility screening looks at two hormones to determine your risk of fertility problems caused by premature ovarian aging: FSH and AMH.
- AMH (anti-Müllerian hormone) is a hormone secreted by the cells of the developing follicles (sacks that contain eggs) in the ovaries. AMH is a strong indicator of awoman's ovarian reserve. As women age, the number of follicles gradually decline, and AMH levels decline with age as well. In essence, we can assess how well a woman’s ovaries are functioning by evaluating her AMH levels.
- FSH (follicle stimulating hormone) is a hormone released by the pituitary gland. FSH stimulates the growth of follicles, and has a role in the maturation of oocytes. The measurement of FSH levels in the blood is one of the most widely used tests to assess a woman's ovarian function. FSH actually rises as ovarian reserve levels fall--higher levels of FSH are an indicator that a woman’s ovarian reserve is below where it should be for her age.
After ovulation, an egg travels from the fallopian tubes to the uterus, and--if sperm is present--it may become fertilized along the way, and settle in the uterus for the 40 weeks of gestation. For a successful pregnancy, the structures of organs like the fallopian tubes, uterus, and cervix must be anatomically able to allow conception to happen and sustain a pregnancy. Abnormalities in the anatomical structures can lead to impaired fertility.
When the two fallopian tubes are blocked by scar tissue or fluid, for example, the ovulated egg cannot meet the sperm. An anatomical problem with the uterus, like a fibroid in an inopportune location, can prevent a fertilized egg from implanting. Anatomical problems are assessed via imaging, such as with a hysterosalpingogram (HSG) or hysterosonogram (HSN).
What’s My Fertility can't screen for an anatomical abnormality, but it's important to note that women with some types of anatomical infertility--for example, tubes blocked due to endometriosis--often also have POA. If What's My Fertilityscreening identifies POA risks for you, it's a good idea to consult a doctor about what your risk status may mean for anatomical issues as well.
#3: Immune system
You may be surprised to learn that the immune system has anything to do with female fertility, but this is one of the important factors to consider. When a fetus starts developing in the uterus, the mother’s immune system has to tolerate the fetus—which is 50% “foreign” to the mother, genetically speaking—in order to resist attacking it as an invader. Women with hyperactive immune systems often have trouble developing this selective tolerance, and experience miscarriages or implantation failures. This is also why women with autoimmune disorders sometimes have difficulty getting pregnant.
Not all fertility specialists test for immune system function, but those that do a thorough workup use blood tests to determine whether a woman’s immune system is functioning normally. Because POA appears to be associated with immunological problems, What’s My Fertility’s screening also takes your immune system into account.
Putting it all together
Typically, female fertility peaks during a woman’s early to mid-20s, and starts declining rapidly by the time she’s in her mid-30s. This age-related decline in female fertility is directly related to what experts call ovarian reserve, i.e., the ovaries’ ability to develop good-quality eggs that would result in healthy pregnancies.
Of course, all three components of female fertility have to work together in order for a pregnancy to occur and be carried to term, but the ovarian reserve is one of the most important (and most often overlooked) aspects of female fertility. This is why What’s My Fertility focuses on this aspect.