{"id":5390,"date":"2019-06-24T17:52:51","date_gmt":"2019-06-24T17:52:51","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/20-10-infertility-3\/"},"modified":"2023-11-30T23:28:53","modified_gmt":"2023-11-30T23:28:53","slug":"20-10-infertility-3","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/20-10-infertility-3\/","title":{"raw":"18.10\u00a0Infertility","rendered":"18.10\u00a0Infertility"},"content":{"raw":" \r\n\r\n[h5p id=\"652\"]\r\n\r\nFigure 18.10.1 Families all have something in common.<\/em>\r\n
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Family Portrait<\/h1>\r\n<\/div>\r\nWhat do all these families (Figure 18.10.1) have in common?\u00a0 They were born!\u00a0 Every person on this planet was conceived, carried in utero and then born.\u00a0 While families come in all shapes, sizes and styles, we all came into existence in the same way.\u00a0 Virtually all human societies past and present \u2014 value having children. Indeed, for many people, parenthood is an important life goal. Unfortunately, some people are unable to achieve that goal because of infertility.\r\n
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What Is Infertility?<\/h1>\r\n<\/div>\r\n[pb_glossary id=\"4813\"]Infertility[\/pb_glossary]<\/strong> is the inability of a sexually mature adult to reproduce by natural means. For scientific and medical purposes, infertility is generally defined as the failure to achieve a successful pregnancy after at least one year of regular, unprotected sexual intercourse. Infertility may be primary or secondary. Primary infertility applies to cases in which an individual has never achieved a successful pregnancy. Secondary infertility applies to cases in which an individual has had at least one successful pregnancy, but fails to achieve another after trying for at least a year. Infertility is a common problem. The government of Canada reported that in 2019, 16% of Canadian couples experience infertility, a number which has doubled since the 1980s. If you look around at the couples you know, that means that almost 1 in 6 of them are having issues with fertility.\r\n
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Causes of Infertility<\/h1>\r\n<\/div>\r\n[pb_glossary id=\"5280\"]Pregnancy[\/pb_glossary] is the result of a multi-step process. In order for a normal pregnancy to occur, a woman must release an [pb_glossary id=\"5099\"]ovum[\/pb_glossary] from one of her [pb_glossary id=\"3487\"]ovaries[\/pb_glossary], the ovum must go through an [pb_glossary id=\"5101\"]oviduct[\/pb_glossary], a man\u2019s [pb_glossary id=\"2506\"]sperm[\/pb_glossary] must fertilize the ovum as it passes through the oviduct, and then the resulting [pb_glossary id=\"2471\"]zygote[\/pb_glossary] must implant in the [pb_glossary id=\"5102\"]uterus[\/pb_glossary]. If there is a problem with any of these steps, [pb_glossary id=\"4813\"]infertility[\/pb_glossary] can result.\r\n\r\nA couple\u2019s infertility may be due to a problem with either the male or the female partner. As shown in the circle graph below (Figure 18.10.2), about 40% of infertility cases are due to female infertility, and about 30% are due to male infertility. The remaining 30% of cases are due to a combination of male and female problems or unknown causes.\r\n\r\n[caption id=\"attachment_5342\" align=\"aligncenter\" width=\"900\"]\"18.10.2 Figure 18.10.2 This graph shows that infertility affects males as often as females, and that the cause of infertility often is unexplained.<\/em>[\/caption]\r\n

Causes of Male Infertility<\/h2>\r\nMale infertility occurs when there are no, or too few, [pb_glossary id=\"2506\"]sperm[\/pb_glossary], or when the sperm are not healthy and motile and cannot travel through the female reproductive tract to fertilize an egg. A common cause of inadequate numbers or motility of sperm is varicocele, which is enlargement of blood vessels in the [pb_glossary id=\"5089\"]scrotum[\/pb_glossary]. This may raise the temperature of the [pb_glossary id=\"3486\"]testes[\/pb_glossary] and adversely affect sperm production. In other cases, there is no problem with the sperm, but there is a blockage in the male reproductive tract that prevents the sperm from being ejaculated.\r\n\r\nFactors that increase a man\u2019s risk of infertility include heavy alcohol use, drug abuse, cigarette smoking, exposure to environmental toxins (such as pesticides or lead), certain medications, serious diseases (such as kidney disease), and radiation or chemotherapy for cancer. Another risk factor is advancing age. Male fertility normally peaks in the mid-twenties and gradually declines after about age 40, although it may never actually drop to zero.\r\n

Causes of Female Infertility<\/h2>\r\nFemale infertility generally occurs due to one of two problems: failure to produce viable [pb_glossary id=\"5099\"]ova[\/pb_glossary] by the [pb_glossary id=\"3487\"]ovaries[\/pb_glossary], or structural problems in the [pb_glossary id=\"5101\"]oviducts<\/span>[\/pb_glossary]<\/span>\u00a0or [pb_glossary id=\"5102\"]uterus[\/pb_glossary]. The most common cause of female infertility is a problem with [pb_glossary id=\"5239\"]ovulation[\/pb_glossary]. Without ovulation, there are no ova to be fertilized. Anovulatory cycles (menstrual cycles in which ovulation does not occur) may be associated with no or irregular menstrual periods, but even regular menstrual periods may be anovulatory for a variety of reasons. The most common cause of anovulatory cycles is [pb_glossary id=\"5577\"]polycystic ovary syndrome (PCOS)<\/strong>[\/pb_glossary], which causes hormone imbalances that can interfere with normal ovulation. Another relatively common cause of anovulation is primary ovarian insufficiency. In this condition, the ovaries stop working normally and producing viable eggs at a relatively early age, generally before the age of 40.<\/span>\r\n\r\nStructural problems with the oviducts or uterus are less common causes of female infertility. The oviducts may be blocked as a result of [pb_glossary id=\"5333\"]endometriosis[\/pb_glossary]. Another possible cause is pelvic inflammatory disease, which occurs when sexually transmitted infections spread to the oviducts or other female reproductive organs (see Figure 18.10.3). The infection may lead to scarring and blockage of the oviducts. If an ovum is produced and the oviducts are functioning \u2014 and a woman has a condition such as uterine fibroids \u2014 implantation in the uterus may not be possible. Uterine fibroids are non-cancerous clumps of tissue and muscle that form on the walls of the uterus.\r\n\r\n[caption id=\"attachment_5344\" align=\"aligncenter\" width=\"1024\"]\"18.10.3 Figure 18.10.3 An infection of the Fallopian tubes may cause scarring and blockage of the tubes, so sperm cannot reach eggs for fertilization.<\/em>[\/caption]\r\n\r\nFactors that increase a woman\u2019s risk of infertility include tobacco smoking, excessive use of alcohol, stress, poor diet, strenuous athletic training, and being overweight or underweight. Advanced age is even more problematic for females than males. Female fertility normally peaks in the mid-twenties, and continuously declines after age 30 and until menopause around the age of 52, after which the ovary no longer releases eggs. About 1\/3 of couples in which the woman is over age 35 have fertility problems. In older women, more cycles are likely to be anovulatory, and the eggs may not be as healthy.\r\n

Diagnosing Causes of Infertility<\/h1>\r\nDiagnosing the cause(s) of a couple\u2019s infertility often requires testing both the man and the woman for potential problems. In men, the [pb_glossary id=\"4885\"]semen[\/pb_glossary] is likely to be examined for the number, shape, and motility of sperm. If problems are found with sperm, further studies are likely to be done, such as medical imaging to look for structural problems with the testes or ducts.\r\n\r\nIn women, the first step is most often determining whether [pb_glossary id=\"5239\"]ovulation[\/pb_glossary] is occurring. This can be done at home by carefully monitoring body temperature (it rises slightly around the time of ovulation) or using a home ovulation test kit, which is available over the counter at most drugstores. Whether or not ovulation is occurring can also be detected with blood tests or ultrasound imaging of the ovaries. If ovulation is occurring normally, then the next step may be an X-ray of the oviducts and uterus to see if there are any blockages or other structural problems. Another approach to examining the female reproductive tract for potential problems is laparoscopy. In this surgical procedure, a tiny camera is inserted into the woman\u2019s abdomen through a small incision. This allows the doctor to directly inspect the reproductive organs.\r\n
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Treating Infertility<\/h1>\r\n<\/div>\r\nInfertility often can be treated successfully. The type of treatment depends on the cause of infertility.\r\n

Treating Male Infertility<\/h2>\r\nMedical problems that interfere with sperm production may be treated with medications or other interventions that may lead to the resumption of normal sperm production.\u00a0If, for example,\u00a0an infection is interfering with sperm production, then antibiotics that clear up the infection may resolve the problem. If there is a blockage in the male reproductive tract that prevents the [pb_glossary id=\"5150\"]ejaculation[\/pb_glossary] of sperm, surgery may be able to remove the blockage. Alternatively, the man\u2019s sperm may be removed from his body and then used for artificial insemination of his partner. In this procedure, the sperm are injected into the woman\u2019s reproductive tract.\r\n

Treating Female Infertility<\/h2>\r\nIn females, it may be possible to correct blocked Fallopian tubes or uterine fibroids with surgery. Ovulation problems, on the other hand, are usually treated with hormones that act either on the [pb_glossary id=\"2938\"]pituitary gland[\/pb_glossary] or on the ovaries. Hormonal treatments that stimulate ovulation often result in more than one egg being ovulated at a time, thus increasing the chances of a woman having twins, triplets, or even higher multiple births. Multiple fetuses are at greater risk of being born too early or having health and developmental problems. The mother is also at greater risk of complications arising during pregnancy. Therefore, the possibility of multiple fetuses should be weighed in making a decision about this type of infertility treatment.\r\n

Assisted Reproductive Technology<\/h2>\r\nSome cases of infertility are treated with\u00a0[pb_glossary id=\"5345\"]assisted reproductive technology (ART)[\/pb_glossary]<\/strong>. This is a collection of medical procedures in which ova are removed from the woman\u2019s body and sperm are taken from the man\u2019s body to be manipulated in ways that increase the chances of fertilization occurring. The eggs and sperm may be injected into one of the woman\u2019s oviducts for fertilization to take place in vivo<\/em>\u00a0(in the body). More commonly, however, the eggs and sperm are mixed together outside the body so fertilization takes place\u00a0in vitro<\/em> (in a test tube or dish in a lab). The latter approach is illustrated in Figure 18.10.4. With in vitro <\/em>fertilization, the fertilized eggs may be allowed to develop into embryos before being placed in the woman\u2019s uterus.\r\n\r\n[caption id=\"attachment_5346\" align=\"aligncenter\" width=\"508\"]\"18.10.4 Figure 18.10.4 This figure shows one way ART procedures may be used to treat infertility. An egg is removed from the female reproductive tract, injected with sperm from her partner, and allowed to develop into an embryo in the lab. Then, the embryo is placed inside the woman\u2019s uterus for implantation and development during the remainder of gestation.<\/em>[\/caption]\r\n\r\nART has about a 40% chance of leading to a live birth in women under the age of 35, but only about a 20%t chance of success in women over the age of 35. Some studies have found a higher-than-average risk of birth defects in children produced by ART procedures, but this may be due to the generally higher ages of the parent \u2014 not the technologies used.\r\n

Other Approaches<\/h2>\r\nOther approaches for certain causes of infertility include the use of a surrogate mother, a gestational carrier, or sperm donation.\r\n