Preface

The purpose of contraception is to prevent an egg from being fertilized by sperm or to prevent the implantation of a fertilized egg in the uterus. There are many methods of contraception. The ideal method of contraception will prevent pregnancy and protect against sexually transmitted diseases. It is essential to understand and approach each method according to the person's sexual needs. Unfortunately, many people of reproductive age do not have access to contraceptive counseling and services. In developing countries, most pregnancies occur in young and teenage women, unexpectedly and undesirably. Approximately 50% of these pregnancies are artificially terminated under unsafe conditions.

Contraception, especially hormonal contraception, has protective characteristics for those who take it, especially in young adolescence. Contraception was practiced for decades on an empirical basis, but the discovery of the contraceptive pill brought about a real revolution in this field. By using scientific techniques, we managed to prevent ovulation, which is the cornerstone of reproduction. Since the outbreak of AIDS, the usage of birth control pills has decreased because they do not offer any protection against sexually transmitted diseases. On the contrary, barrier contraception that offers protection from STDs prevents direct contact. The contraceptive pill continues to be a unique scientific achievement, which if combined with intrauterine devices creates a protective shield against unwanted pregnancy. The clinical implementation of oral contraception dates back to the 1960s, but its history goes back to the beginning of the 20th century when experimental data showed that the ovaries were organs with hormonal activity. Adolescence is a period in which many physical, emotional, and psychological changes occur in a relatively short time. In this context, one's sexuality, especially in young girls, is developed, with young women particularly vulnerable to possible unwanted pregnancies and STDs. The ever-decreasing age of onset of sexual relations that has been observed worldwide in recent years urges the need for proper sex education and informing teenagers about their contraceptive options. Undoubtedly, accessing information is extremely easy, but there are still many misunderstandings about the methods of contraception today.

The factors that determine whether pregnancy will take place include the fertility of both partners, the year of having intercourse in relation to the time of ovulation, the method of contraception used, and the endogenous efficiency as well as the correct usage of the method. It is impossible to approximate the effectiveness of a contraceptive method isolated from the other factors. Besides effectiveness, contraceptive methods are evaluated by their side effects, ease of implementation, reversibility, and acceptance by the population. The best way to determine the effectiveness of a contraceptive method is by long-term evaluation of a group of sexually active women who use the specific method for a particular period and observing how often pregnancy occurs. The failure rate of each contraceptive method expressed as pregnancies per 100 women per year, is determined by calculating the Pearl Index specific to each method. This involves dividing the number of pregnancies by the total number of months in the observed period for the pairs and then multiplying the resulting quotient by 1200. A method is considered effective when the number of unwanted pregnancies is less than 2 in 100 women who use the method for a year, moderately effective when the rate of unintended pregnancies is up to 10%, and less effective when the rate of unwanted pregnancies is more than 10%. The efficiency of a

method can thus be expressed with two values. The one value results from the set of pairs in which the contraceptive method is used as usual. Therefore, a particular method may be effective for one couple, but not for others. That is, it is a kind of average price effectiveness. The other value refers to the percentage of unwanted pregnancies when the method is used optimally, that is, when used correctly and consistently.

Currently, the World Health Organization (WHO) recommends a 24-month postpartum interval for a subsequent pregnancy. It is estimated that effective family planning globally could prevent 1 in 10 deaths among fetuses by helping women to give birth at least 2 years later because a short period of less than 12 months between pregnancies increases the risk of complications such as low birth weight, premature birth, stillbirth, and neonatal death. Defining contraceptive failure is not easy, as it depends on the population studied. Studies in a young population will suggest a higher failure rate than in an older age group, as fertility is higher in younger people. Consequently, caution is required when interpreting the relevant numbers. "Method failure" includes the inherent risk of failure provided the method is used properly. Percentages are measured in units per 100 women years to the number of women who would become pregnant if 100 of them used this method of contraception for one year. User failure is the failure rate when the method is not used correctly (missed tablets, delayed injections, drug interactions).

With proper guidance from family planning centers, if used consistently and correctly, hormonal contraception (combined hormonal methods, progestogen-only pills, injectables, implants, and intrauterine devices) and non-hormonal methods (copper intrauterine devices [Cu-IUD], sterilization in males and females) are more than 99% effective in preventing pregnancy.

#### **Panagiotis Tsikouras and Nikolaos Nikolettos** Professor, Department of Obstetrics and Gynecology, Democritus University of Thrace, Alexandroupolis, Greece

#### **Werner Rath**

Professor, Gynecology and Obstetrics in the Faculty of Medicine, University of Kiel, Kiel, Germany

#### **Friedrich Von Tempelhoff**

Professor, Gynecology and Obstetrics, St. Vinzenz Teaching Hospital, Hanau, Germany Section 1
