Birth control pills contain 2 hormones – estrogen and progestin in various combinations, which are close to the natural sex hormones produced in each woman’s ovary. The tablets usually contain an estrogen component ethinyl estradiol and as a progestin component – levonorgestrel or norethindrone (these are synthetic analogs of progesterone). The contraceptive effect of combined oral contraceptives is explained by the presence of several mechanisms of action.
Combination oral contraceptives: mechanism of action
Birth control pills serve as one of the most reliable types of contraception. There are 2 types of modern drugs, the first consists of one hormone – a gestagen, and the second contains two hormones – estradiol (estrogen) and gestagen. The first option is recommended for women who are breastfeeding and over the age of 35 years, especially those who are smoking. And the second option is prescribed to most women since the action of the tablets is very similar to physiological and they cause fewer side effects than progestin-only tablets.
No doubt, the effectiveness of the drug is explained by the gestagen. In most cases, it suppresses ovulation or leads to insufficiency of the second phase of the cycle, the corpus luteum produces very little progesterone and the implantation and development of a fertilized egg become impossible. But you should not worry, the effect of birth control pills is reversible in the absolute majority of cases. That is, the woman will be able to conceive immediately or almost immediately after discontinuation of the drug.
The second hormone, estrogen, prevents the development of a dominant follicle, as well as prevents premature detachment of the endometrium. This helps to avoid intermenstrual secretions. Keep in mind that sometimes hormonal contraception pills fails and the body needs to get used to the hormonal contraceptive. Usually, the period of adaptation lasts up to three months. If this side effect lasts longer, you need to change the drug.
So, in short, birth control pills:
- inhibit ovulation (maturation and release of the egg);
- help to thicken mucus in the cervix, making it difficult for sperm to reach it;
- change the lining of the uterus, which prevents attaching a fertilized egg to it;
- reduce the motility of sperm in the fallopian tubes.
The combination of all these factors makes combined oral contraceptives the most effective method of preventing unwanted pregnancy.
When does birth control start working?
If a woman starts taking the first package of the drug as required by the instructions, that is, from the first day of the cycle, then they work right away. If the reception started from the fifth day of the period, then a woman should use additional contraceptive option during the first 7-14 days (preferably condoms) By the way, the contraceptive effect of the drug is preserved in the seven-day break in its use, during which menstruation begins. It turns out that’s how birth control pills work during this time period – the woman does not take them but she is reliably protected from unwanted pregnancy. This is the so-called sterile period, when a woman cannot conceive even when she is taking pills. This knowledge is used in the calendar method. But this option is much less reliable than hormonal contraceptives.
How long do birth control pills work? What happens if you miss a dose?
The effect of one pill is fully preserved for 24 hours. Then, over the next 12 hours, the contraceptive effect is slightly reduced but remains sufficient. After 24 hours, it begins to fall sharply, a woman can have intermenstrual bleeding and even conceive a child. If you miss a pill, you should follow the instructions found in the medication package insert.
How does emergency contraception work?
Today, women can also use emergency contraception. This is the last-generation contraceptive pill, which must be taken within 72 hours after unprotected sex. This option provides reliable protection from an unplanned pregnancy. The emergency contraceptive pill contains the same active hormonal component (an analogue of the natural female sex hormone progesterone), like other hormonal oral contraceptives. But the dosage of the hormonal component is much higher, which ensures its high efficiency.
Category: Birth control
Tags: birth control pills, contraception, Contraceptives, women's health