Contraception, also known as birth control is a means to prevent pregnancy. Contraception empowers women to control their fertility and plan the stages in their lives. It also protects women from the negative effects of unplanned pregnancy, including abortion.
For pregnancy to occur, four events must occur: ovulation must happen; sperm must be deposited in the genital tract; the sperm must fertilise the egg in the fallopian tube, and finally the fertilised egg must implant in the cavity of the uterus.
Different methods of contraception work to block one of these four events from taking place, thereby preventing pregnancy.
Methods to prevent ovulation are mostly hormone based, such as oral contraceptives, patch, injection and implant. To prevent sperm from meeting the egg, the barrier method of using condoms has to be employed or the natural methods of withdrawal method and the calendar rhythm method can be practiced. To prevent the fertilized egg to be implanted in the uterus, an intrauterine contraceptive device must be inserted.
Making a choice of contraceptive method
There are many forms of contraception which a woman has to choose from. That choice depends on the particular situation the woman is in, her age, relationship status, her fertility wishes and lifestyle preferences. In addition, family history of certain illness, frequency of sexual activity as well as a woman’s comfort level using a particular method of contraception are considerations which come into play when making this choice. The length of interval between planned pregnancy is also another important consideration. Although most types of contraception allow fertility to resume the moment almost immediately after the contraceptive method is stopped, some (like the implants and the injectables) may take a few months before fertility is resumed. Finally, the cost and reliability of a particular method also needs to be considered when making a choice.
Below is a short write-up on the most common example from each of the different categories of contraception.
Prevention of ovulation
The most common example of hormonal based contraception is the combined oral contraceptive (COC). COC works by preventing the release of eggs from the ovaries. It is 98-99% effective if taken daily at the correct timing. The pros of this method, which make it attractive to most women seeking contraception, is that it regulates the menstrual cycle, lessen both the menstrual flow and symptoms of pre-menstrual syndrome. Furthermore, research has demonstrated that the oral contraceptive pill also reduces the risk of developing ovarian and endometrial cancer. Missing a pill or two will decrease the efficacy of this method, which makes it less attractive for women who tend to be forgetful. The pill is not recommended for women over 40 years of age who smoke, or for women with high blood pressure, diabetes, liver or kidney disease or high cholesterol.
Prevent sperm from meeting the egg
The male condom is an example of barrier method of contraception; it is also the most common form of contraception in Singapore. The condom is a latex sheath which is used to cover a man’s penis to prevent sperm from entering the woman’s vagina. The main drawback of the condom is that it is highly dependent on the partner for usage. Also, condoms can break or slip off, making their reliability low. However, condoms have the additional benefit of being the only method of contraception that protects against most sexually transmitted infections. Hence a combination of condoms and another method of contraception may be more appropriate if you have multiple partners.
Prevent the fertilized egg from being implanted in the uterus
Intrauterine device (IUD) and intrauterine system (IUS) are devices that are placed in the uterine cavity to prevent implantation of fertilised egg or embryo. Intrauterine devices (IUD) provide contraceptive protection for 3 to 5 years depending on its make. Although IUD may increase menstrual bleeding and cramping in the first few months after insertion, these symptoms will usually abate after a few months.
Intrauterine systems (IUS) are similar to IUDs except they release a daily dose of 20 micrograms levonorgestrel (a type of hormone) into the cavity of the womb. Not only does it prevent implantation of the embryo, it also causes thickening of the cervical mucus, and suppresses growth of the endometrium. The IUS lasts for five years, and over time, slowly reduces menstruation, making it well suited for women who experience heavy menses. The failure rate of the IUS is the lowest amongst all types of contraception, making it the most reliable.
Dr. Chee Jing Jye would be able to discuss the various options of contraception with you and determine which is most suited for you based on your own unique situation.