Sharon Perkins - Getting Pregnant For Dummies

A popular test now is called carrier screening. Many people carry a number of gene defects for recessive diseases. For a recessive disease to produce the actual disease, a person has to inherit an abnormal gene form both parents. Thus, many people have unknown gene errors and are disease free, but could have children that develop the genetic disease if the partner also has the gene defect. The advances in genetic testing now permit testing people for many gene defects. Knowing this, a couple can determine whether their children would be at risk for developing the disease. Using IVF and preimplantation genetic diagnosis, the couple can avoid creating a child with the disease.

As if testing your genes is not enough, scientists are now looking at how we can change your genetic structure, or the genetic structure of your embryos! While it sounds more like science fiction than real medicine, there are some new ideas in the field of genetics that may someday help conquer infertility.

An expanding area of research for genetic diseases focuses on how the genetic code is actually read. It turns out that while there is a core code, inherited unchanged from generation to generation, the cell is able to modify how the code is read based upon environmental and developmental conditions. Cells do this by adding molecules to the core code, which is called epigenetics. For example, one theory of how endometriosis forms is that molecules called methyl groups can either be added or removed from the core genetic code, creating new instructions from the genetic code that leads to the formation of endometriosis. Endometriosis is a very complex disease, and this is not the only reason a person develops endometriosis, but the process may add to the risk for developing endometriosis.

A cell requires considerable energy to perform the work it does. The energy is generated by a small structure within the cell called mitochondria. Mitochondria are similar to bacteria and have their own set of chromosomes. When errors occur in these genes, the mitochondria do not perform well. This can lead to devastating diseases. One treatment that is being developed is to take normal mitochondria from an embryonic cell and transfer it into the cell from an affected embryo.

A result of more sophisticated chromosome testing of preimplantation embryos is the discovery that not all embryos are either completely euploid or completely aneuploid. Some embryos have cells that have the correct number of chromosomes while other cells in the same embryo have the wrong number of chromosomes. This is called mosaicism. Currently, research is attempting to determine what percentage of mosaicism is safe for transfer of a mosaic embryo.

A final advancement is the ability to genetically modify the genetic code of an embryo. The technology uses a procedure called CRISPR (technically CRISPR-Cas9). The use of this for clinical medicine is quite a ways off, but the implications are immense. In theory, it may become possible to actually alter the genetic code. This could provide a way to cure inherited diseases or reduce genetic risk factors for a number of chronic diseases. The use of genetics to improve the human condition is called eugenics. The ability to alter the genetic code elevates the field of eugenics to a new level that could challenge both ethics and the legal system. So once again, just as IVF challenged the social environment of reproduction, genetic modification may challenge the social system in very difficult and complex ways.

The field of genetics is extremely complex and fluid. There are people who have advanced training in genetics. They are extremely important for explaining what the results of genetic tests mean and how to use the information from genetic testing to a person’s best advantage. Hospitals, fertility practices, and genetic testing companies have genetic counselors available for consultation. The internet is also a source of information. The bottom line is that genetics is an expanding part of medicine. Its role will become even more important as more is discovered about the genetic code and how it works.

Chapter 4

IN THIS CHAPTER

Altering your lifestyle for conception

Understanding sexually transmitted infections and diseases

Dispelling common myths

Getting that baseline physical

Even though you’re probably anxious to get started on baby making, take a little time to make sure that you’re in the best possible condition for conceiving a healthy baby. This means making sure that you’re not carrying an infection that may harm you or your baby and taking a look at your lifestyle habits, good and bad. In this chapter, we tell you how to get in shape physically if you’re trying to get pregnant and discuss some behavior that may be decreasing your odds of getting pregnant. We also take a look at how what you eat could influence your chance of conceiving.

“Everything in moderation” is certainly a good motto for habits, good and bad. Too much exercise can have a less-than-desirable effect, while coffee, drunk in moderation, can be benign. But, before you say yes to things that are better left in the “no” category, consider that some things are best eliminated entirely, particularly when you’re trying to conceive.

Smoking is bad for you. We all know it. Yet roughly 14 percent of women and 18 percent of men in the United States still smoke. While cigarette warning labels tell you they are addictive, they do not tell you that smoking impacts your reproductive health. Need some good reasons to quit? Here are a few:

Women who’ve smoked more than 100 cigarettes in their lifetime have a 14 percent greater risk of infertility.

Smokers take longer to conceive.

Smokers increase their relative risk for miscarriage by 1 percent for each cigarette they smoke a day. So, if you are 35 years old, you have a 20 percent chance of miscarriage (in general). If you smoke five cigarettes a day, you now have a 25 percent chance of miscarrying. But former smokers have the same risk of miscarriage as those who have never smoked, so quitting can really make a difference!

Smokers are two to four times more likely to have an ectopic pregnancy (one that implants in the fallopian tube rather than in the uterus, a topic we discuss in detail in Chapter 13) as smoking alters the structure and function of the tubes.

Smokers go through menopause earlier because smoking increases free radicals. Free radicals are substances that kill all cells, including eggs, decreasing the number of years pregnancy can occur. Smokers go through menopause three to four years earlier than nonsmokers. This could mean that a 38-year-old smoker is more like a 42-year-old nonsmoker, which, based upon age, would represent a significant decline in fertility.Smokers also have lower AMH (anti-muellerian hormone) levels than nonsmokers undergoing IVF. AMH is a protein made by egg units (follicles). More egg units means higher AMH, and in terms of eggs, more is always better than fewer. (We talk more about the impact of AMH in Chapter 11.)