When it comes to fertilization and conception, there are two terms that doctors commonly use: in vitro and in vivo. Each has a different meaning and implications for fertility. Understanding a couple’s options when it comes to conceiving can help.
In vitro and in vivo are both Latin terms. When translated, in vivo means “in life.” In vitro means “in glass.” While these terms apply to fertility treatments, they also apply to the scientific world in general. For example, when scientists perform an in vitro study, they are performing studies using test tubes, petri dishes, and other instruments. Scientists often using in vitro studies to isolate a small part of a larger organism. This could include specific types of cells. Other in vitro studies may focus on bacteria and viruses. While in vitro studies have many clinical applications, they don’t always translate perfectly into how a cell will respond or act when it is in a living person’s body. In vitro studies are important to clinical research, as are in vivo studies. In vivo studies involve experiments with humans and other animals. Many ethical concerns exist as to how to safely and effectively perform in vivo studies. Not all experiments can be performed if they have the potential to cause serious harm to people.
In the field of reproductive medicine, the concepts of in vivo vs. in vitro are very important. In vivo fertilization refers to fertilization that occurs in the human body using sexually reproductive organs. Another name for this is “natural” reproduction. This is in contrast with in vitro fertilization, where fertilization occurs in a lab and outside of the human body.
While in vitro fertilization may not take place as a “natural” form of fertilization, it does involve using the same components as in vivo fertilization. During in vitro fertilization, a doctor prescribes fertility medications to a woman. She takes these medicines as a means to encourage her body to do what is called “superovulation.” This is when her Fallopian tubes release more than one egg in a fertility cycle. The effect is beneficial because a doctor will use a special technique that involves extracting the eggs using a needle. The eggs are then preserved in a special substance known as a “medium” that allows the eggs to be transferred to a laboratory. A man will then produce his sperm, usually via masturbation, that is also transferred to a laboratory.
A laboratory technician will combine the sperm and egg with the goal of fertilizing the egg. In about five days, the fertilized egg will ideally become an embryo. The embryo or embryos, in some instances, are then transferred to a woman’s uterus via a special technique performed in a doctor’s office. Ideally, the fertilized embryo will implant into the uterus and pregnancy will occur.
According to “Parents” magazine, a women is born with all the eggs she will have across her lifetime. This number is somewhere between 1 and 2 million eggs. As she ages, a woman has fewer available eggs, and the eggs tend to be less healthy or viable. Regardless of an in vivo or an in vitro approach, a woman only has a slim period of time when she can get pregnant – about one week out of the month.
For women, age plays a great deal into whether or not they become pregnant. When doctors attempt to determine fertility, they will often take into account the age of the mother when predicting the likelihood that she will get pregnant. This is due to the decline in egg availability and quality. According to “Parents’ magazine, the likelihood that a woman will get pregnant if she attempts to conceive “in vivo” include:
Most women do not seek in vitro fertilization unless they have already had difficulty conceiving, usually after they have been trying to get pregnant for a year. According to the American Pregnancy Association, the likelihood of a life birth rate with an IVF cycle includes:
However, a person should keep in mind these statistics are per IVF cycle and the earlier-mentioned statistics are for women trying to get pregnant over the course of a year.
Regardless of the chances for success related to age, a woman should always talk to her doctor about her individual chances for conceiving. A woman may have certain benefits and drawbacks that could impact her ability to conceive.
American Pregnancy Association: In Vitro Fertilization (IVF)
Reproduction: Early History of In Vitro Fertilization
Santa Barbara Independent: In Vitro Fertilization, Part I: A Brief History
VeryWell: In Vitro Definition