What is Normal Fertility and When Does it Become Infertility?
What is Infertility?
Most people will have the strong desire to conceive a child at some point during their lifetime. Understanding what defines normal fertility is crucial to helping a person, or couple, know when it is time to seek help. Most couples (approximately 85%) will achieve pregnancy within one year of trying, with the greatest likelihood of conception occurring during the earlier months. Only an additional 7% of couples will conceive in the second year. As a result, infertility has come to be defined as the inability to conceive within 12 months. This diagnosis is therefore shared by 15% of couples attempting to conceive. We generally recommend seeking the help of a reproductive endocrinologist if conception has not occurred within 12 months. However, there are various scenarios where one may be advised to seek help earlier. These include:
- Infrequent menstrual periods: When a woman has regular menstrual periods, defined as regular cycles occurring every 21 to 35 days, this almost always indicates that she ovulates regularly. Ovulation of the egg occurs approximately 2 weeks before the start of the next period. If a woman has cycles at intervals of greater than 35 days, it may indicate that she is not ovulating an egg predictably, or even at all. Ovulation of the egg is essential for pregnancy. Therefore, we recommend an evaluation if menstrual cycles are infrequent or irregular in a couple attempting pregnancy.
- Female age of 35 years or older: For unclear reasons, egg numbers decrease at a rapid rate as women age. Furthermore, as aging occurs, egg quality, or the likelihood of an egg being genetically normal, decreases. Therefore we recommend a fertility evaluation if a couple has been attempting pregnancy for 6 months or more when the woman is 35 years of age or older.
- A history of pelvic infections or sexually transmitted diseases: Sexually transmitted infections, such as chlamydia or gonorrhea, can cause inflammation and permanent scarring of the fallopian tubes. The presence of open tubes is essential for natural conception, as sperm must traverse the tubes in order to reach and fertilize the ovulated egg. We recommend immediate evaluation for a couple attempting pregnancy when the woman has a prior history of pelvic infection. As part of the fertility evaluation, we will perform an HSG, a test designed to evaluate if the fallopian tubes are open.
- Known uterine fibroids or endometrial polyps: Uterine abnormalities, such as fibroids that indent the endometrial cavity and endometrial polyps, can impair how the endometrium (the lining of the uterus) and embryo interact to lower implantation and pregnancy rates. These abnormalities can also cause irregular bleeding between menstrual cycles. Evaluation should be pursued by 6 months of attempted pregnancy in women with a known history of these abnormalities or a history of bleeding between menstrual cycles. The main approach to correcting or removing these uterine abnormalities is by hysteroscopy, a surgical method by which a narrow scope with a camera is placed within the uterine cavity. Instruments can be introduced through the hysteroscope, allowing the surgeon to remove or correct any anatomic abnormalities.
- Known male factor semen abnormalities: If a male partner has a history of infertility with a prior partner, or if there are abnormalities on his semen analysis, then we advise earlier fertility evaluation, ideally within 6 months of attempting pregnancy.
What is Involved in the Fertility Evaluation?
History and physical examination – First and foremost, your fertility physician will take a very thorough medical and fertility history. Your doctor may ask you many of the following questions: How long have you been trying to get pregnant? How often are you having intercourse? Do you have pain with menstrual periods or intercourse? Have you been pregnant before? What happened with your prior pregnancies? Have you had any sexually transmitted infections or abnormal pap smears? How often do you have menstrual cycles? Do you have any medical problems or prior surgeries? Do you have a family history of medical problems? These and many other questions will help your physician design a specific evaluation and potential treatment for you. In addition to a careful history, a physical evaluation may also be performed.
Transvaginal ultrasound – Ultrasound is an important tool in evaluating the structure of the uterus, tubes, and ovaries. Ultrasound can detect uterine abnormalities such as fibroids and polyps, distal fallopian tube occlusion, and ovarian abnormalities including ovarian cysts. Additionally, transvaginal ultrasound affords the opportunity for your physician to assess the relative number of available eggs. This measurement is called the antral follicle count and may correlate with fertility potential.
Laboratory testing – Depending on the results of the evaluation discussed above, your physician may request specific blood tests. The most common of these tests include measurements of blood levels of certain hormones such as estradiol and FSH, which are related to ovarian function and overall egg numbers; TSH, which assesses thyroid function; and prolactin, a hormone that can affect menstrual function if elevated.
Hysterosalpingogram (HSG) – This test is essential for evaluating fallopian tubal patency, uterine filling defects such as fibroids and polyps, and scarring of the uterine cavity (Asherman syndrome). Many uterine and tubal abnormalities detected by the HSG can be surgically corrected.
Semen analysis – The semen analysis is the main test to evaluate the male partner. There are four parameters analyzed: 1) semen volume – should be at least 1.5 to 2 ml. A smaller amount may suggest a structural or hormonal problem leading to deficient semen production; 2) sperm concentration – normal concentration should be at least 20 million sperm per 1 ml of semen. A lower concentration may lead to a lower chance for conception without treatment; 3) sperm motility or movement – a normal motility should be at least 50%. Less than 50% motility may significantly affect the ability for sperm to fertilize the egg without therapy; and (4) morphology, or shape – there are three parts of the sperm that are analyzed for morphology: the head, midpeice, and tail. Abnormality in any of those regions may indicate abnormal sperm function and compromise the ability of sperm to fertilize the egg. Ideally, using strict morphology criteria, a minimum of 5 – 15% normal forms leads to a better ability for sperm to fertilize the egg. An abnormal semen analysis warrants a further evaluation usually by a reproductive urologist. Your physician will refer you to a reproductive urologist if appropriate.
What are the Common Causes of Infertility?
What Causes Infertility?
1) Advancing maternal age: Historically before the latter 20th century, women were conceiving in their teens and twenties, when age-related abnormalities with the egg were not evident. However, in our modern era, women are delaying child birth until their thirties and forties, which has lead to the discovery of the adverse effect of advanced maternal age on egg function. In fact, female age-related infertility is the most common cause of infertility today. For unknown reasons, as women age, egg numbers decrease at a rapid rate. And as aging occurs, egg quality, or the likelihood of an egg being genetically normal, decreases as well. Hence the ability to conceive a normal pregnancy decreases from when a woman is in her early 30s into her 40s. A woman is rarely fertile beyond the age of 45. This applies to the ability to conceive with her eggs, but not with donor eggs.
2) Ovulation disorders: Normal and regular ovulation, or release of a mature egg, is essential for women to conceive naturally. Ovulation often can be detected by keeping a menstrual calendar or using an ovulation predictor kit. There are many disorders that may impact the ability for a woman to ovulate normally. The most common disorders impacting ovulation include polycystic ovary syndrome (PCOS), hypogonadotropic hypogonadism (from signaling problems in the brain), and ovarian insufficiency (from problems of the ovary). If your cycles are infrequent or irregular, your doctor will examine you and perform the appropriate testing to discover which problem you may have and present the appropriate treatment options.
3) Tubal occlusion (blockage): As discussed previously, a history of sexually transmitted infections including chlamydia, gonorrhea, or pelvic inflammatory disease can predispose a woman to having blocked fallopian tubes. Tubal occlusion is a cause of infertility because an ovulated egg is unable to be fertilized by sperm or to reach the endometrial cavity. If both tubes are blocked, then in vitro fertilization (IVF) is required. If a tube is blocked and filled with fluid (called a hydrosalpinx), then minimally invasive surgery (laparoscopy or hysteroscopy) to either remove the tube or block/separate it from the uterus prior to any fertility treatments is recommended.
4) Uterine fibroids: Fibroids are very common (approximately 40% of women may have them) and the mere presence alone does not necessarily cause infertility. There are three types of fibroids: 1) subserosal, or fibroids that extend more than 50% outside of the uterus; 2) intramural, where the majority of the fibroid is within the muscle of the uterus without any indentation of the uterine cavity; and 3) submucosal, or fibroids the project into the uterine cavity. Submucosal fibroids are the type if fibroid that has clearly been demonstrated to reduce pregnancy rate, roughly by 50%, and removal of which will double pregnancy rate. In some cases, simply removing the submucosal fibroid solves infertility. Often, but not always, submucosal fibroids can cause heavy periods, or bleeding between periods. There is more controversy regarding intramural fibroids, where larger ones may have an impact and may necessitate removal. Subserosal fibroids do not affect pregnancy. Your physician will examine you carefully to determine if you have fibroids and if removal is necessary.
5) Endometrial polyps: Endometrial polyps are finger-like growths in the uterine cavity arising from the lining of the uterus, called the endometrium, These abnormalities are rarely associated with cancer (<1% in a woman before menopause), but polyps are can decrease fertility by up to 50% according to some studies. Removal of polyps by the minimally invasive procedure hysteroscopy is associated with a doubling of pregnancy rate. In some cases, simply removing the polyp solves infertility.
6) Male factors affecting sperm function: Male factor infertility has been associated as a contributing factor causing infertility in 40-50% percent of cases, and as the sole cause for infertility in 15-20% percent of cases. If a semen analysis is found to be abnormal, generally it is first repeated to confirm the abnormality. Once confirmed, the male partner is referred to a reproductive urologist, especially if the abnormality is severe. In some cases, the reproductive urologist can improve semen function by recommending certain lifestyle changes, by hormonal treatments, or by surgery. In most cases however, sperm function may not improve and therefore any attempts at pregnancy may require additional treatments or procedures performed by our clinic. Options include intrauterine insemination (also known as IUI) or IVF with intracytoplasmic sperm injection (also known as ICSI).