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Oral Contraceptive Pills: Benefits, Types, How To Use, Effectiveness, Adverse Effects And Other Details

Contraception is defined as an act of preventing undesired pregnancy. Among many contraceptive methods like contraceptive devices, procedure, medicines and behaviour, oral contraceptive pills are among the commonly prescribed contraceptives to women of reproductive age, due to its high safety and effectiveness.

Pic Credit: Hand photo created by jcomp -

According to a study published in 2014, around 100 million women worldwide use pills as a method of contraception. Pills were introduced in the early 1960s, giving women a chance for the first time in history to actively take part in family planning. [1]

In this article, we will discuss oral contraceptive pills, their benefits, types, uses, how do they work, adverse effects and other details.


What Are Oral Contraceptive Pills?

Oral contraceptive (OC) pills, commonly known as ‘the pill' or birth control pills or hormonal pills, contain hormones (one or both progesterone and oestrogen) that helps block the release of eggs from the ovaries or thicken the mucus from the cervix to prevent the fertilisation of eggs and sperm and thus, preventing pregnancy. [2]

The OC pills are taken by mouth and come in different types. They are to be taken only after consulting a medical expert as they know which types of OC pills will work best for you, depending on your age, health and pre-existing conditions.

Benefits Of Oral Contraceptive Pills

Some of the benefits of oral contraceptive pills include: [3]

  • Prevents unwanted pregnancy.
  • Do not interrupt sex.
  • Reduces the risk of ovarian cancer and endometrial.
  • Can be used during breastfeeding.
  • Reduces the risk of acute pelvic inflammatory diseases.
  • Protect against ectopic pregnancies.
  • Decreases the risk of iron deficiency anaemia.
  • Decreases the risk of benign breast cancer.
  • Protects against uterine fibroids.
  • Prevents the progression of ovarian cysts.
  • Protect against gonorrhoea.

Types Of Oral Contraceptive Pills

There are two main types of oral contraceptive pills: hormonal and non-hormonal. Hormonal pills include combined hormonal contraceptives and progestin-only (PO) contraceptives, along with emergency contraceptive pills (ECP), while non-hormonal pills include Centchroman. [4]

Hormonal Oral Contraceptive Pills

1. Combined hormonal contraceptives

These pills release a small amount of progesterone and oestrogen into the blood and should be taken daily, whether you have had intercourse or not. Its failure rate is 0.3 pregnancy per 100 women.

Combined pills make for the highest OC pills used by women between ages 15-45 years. They come in several forms such as: [5]

  • Monophasic pills: Contains equal amounts of progesterone and oestrogen in each active pill.
  • Biphasic pills: Contains the same amount of oestrogen in each pill, but the progesterone dose is high in pills from the mid of the cycle.
  • Triphasic pills: Contains three different doses of oestrogen and progesterone that varies every seven days.
  • Four-phasic pills: Contains four different doses of the hormones for a cycle of 28 days.
  • Ninety-one-day pills: Contains active pills for 84 days and the remaining seven pills are inactive and are taken during menstruation. It causes periods after every three months.
  • 2. Progesterone-only contraceptives

    They provide a constant dose of just one hormone progesterone. The PO pills are also taken daily by women and contain only active pills. They release a small dose of progesterone each day and are mainly prescribed to women above 40. [6]

    3. Emergency contraceptive (EC)

    It comes in a pack of single tablets and is suggested to be taken to prevent pregnancy in an emergency situation like unprotected sex. The EC is taken within 72 hours. [7]

    Non-Hormonal Oral Contraceptive Pill

    It contains a drug called Centchroman under the trade name "Chhaya". Centchroman is the first nonsteroidal OC pill that does not contain artificial hormones but anti-implantation agents that help prevent pregnancy by interfering with the implantation of the blastocyst in the uterus and not by disturbing the balance of hormones. [8]

    A single pill is given twice a week for the first three months and then once a week thereafter.


How Do Oral Contraceptive Pills Work?

The progesterone hormone in the combined pills is the main hormone that helps in preventing pregnancy. The hormone prevents ovulation (release of an egg from the ovary into your fallopian tube) by preventing follicular development.

Progesterone in the pills also signals the hypothalamus to lower the pulse frequency of gonadotropin-releasing hormone (GRH) which is responsible for the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the hormones that cause an egg to grow and to be released for ovulation. [9]

When the production of these two hormones is lowered, the development of a follicle (a fluid-filled sac that contains an immature egg) stops and its release is also prevented, thus, preventing ovulation.

Progesterone also makes the cervical mucus thick so as to inhibit the sperm from sliding to the cervix and meet with an egg for fertilisation. It also thins the lining of the endometrium to prevent the implantation of an egg after fertilisation.

Estrogen in combined pills serves three main purposes: lower the pulse frequency of GRH, prevents irregular shedding and bleeding and thus, manages menstruation. [10]


How To Use Oral Contraceptive Pills?

Combination pills come in a monthly pack of 21, 24, 28 and 91 days. Progesterone-only pills come in a pack of 28 while emergency contraceptives contain just a single pill.

Combinational pills are suggested to be taken daily with each pill a day and at the same time. If you missed a tablet for more than 24 hours, chances are that its efficacy could be reduced and the failure rate may increase. They should be taken as:

  • 21-day pack: One tablet each for 21 days and no tablet for seven days. During these seven days, your periods will come. Start another pack after a week.
  • 28-day pack: It contains two different coloured pills. Here, 21 pills are of the same colour containing active hormones while the remaining seven are of different colours taken during the seven days when you bleed. A new pack is started the next day after the completion of a packet.
  • 91-day pack: It contains a total of 91 tablets of two different colours. The tablets for 84 days are single coloured and are to be taken daily at the same time of the day. The remaining seven tablets are of another colour and are to be taken for a week after 84 days during which you will bleed. This pack is meant to cause a period after every three months.
  • Progesterone-only pills come in a pack of 28 which needs to be taken daily within 3-12 hours of the same time each day. There is no hormone break of pills in this pack, therefore, start a new pack as soon as one pack ends.

    Note: Oral contraceptive pills should be taken even if there is no intercourse. Also, if you vomit within two hours of taking the medicine, another pill should be taken as soon as possible.

    Effectiveness Of Oral Contraceptive Pills

    • Combined hormonal contraceptives: With timely use, its effectiveness is 0.3 pregnancy per 100 women, while with improper use, the effectiveness increased to 8 pregnancies per 100 women. Meaning, with improper use, 8 out of 100 women may still get pregnant.
    • Progesterone-only contraceptives: With timely use, its effectiveness on breastfeeding women is 0.3 pregnancy per 100 women and on non-breastfeeding women, 0.9 pregnancy per 100 women. With typical use, it increases to 1 in the prior while 3-10 in the latter.
    • Emergency contraceptive pill: Its effectiveness per 100 women is 2 pregnancies for combination pills and 1 pregnancy for progesterone-only pill. [4]

Factors That May Affect Oral Contraceptive Pills

Though birth control pills provide an effective way to prevent undesired pregnancy, certain factors can interfere with OC pills and reduce their effectiveness or cause certain side effects, even if you take them on time every day. The factors include:

  • Antibiotics like rifampin. However, there are very few episodes of such interaction. [11]
  • Antiretrovirals for HIV. [12]
  • Herbs like St. John's Wort
  • Heart diseases
  • Pre-existing chronic diseases such as diabetes for longer periods.
  • Overweight or obesity
  • Severe migraine problems
  • Smoking habits
  • Other medications you are on.
  • Breast cancer
  • Whether you are breastfeeding.
  • Disease of the liver of the gallbladder.
  • Any recent episode of miscarriage or abortion.
  • Other Uses Of Oral Contraceptive Pills Apart From Contraception

    Some of the other clinical benefits of OC pills include: [13]

    • Endometriosis
    • Polycystic ovary syndrome
    • Acute acne problems
    • Heavy bleeding
    • Premenstrual syndrome
    • Amenorrhea due to low weight, stress or exercise
    • Menstrual cramps
    • Primary ovarian insufficiency
    • Menorrhagia

Adverse Effects Of Oral Contraceptive Pills

Starting on OC pills may cause certain mild to moderate side effects which may disappear with continuous use. It includes:

  • Nausea
  • Abdominal cramps
  • Low sex drive
  • Increase in vaginal discharge
  • Headache
  • Breast tenderness
  • Some OC pills can cause severe headaches and frequent vomiting. Also, in some patients, there is an increased risk of venous thromboembolism or blood clots. Therefore, if you observe any of the symptoms, consult a medical expert soon for a change of the pills. If you have a history of heart disease or blood clots, it is better to talk to your doctor beforehand so that they can prescribe OC accordingly. [14]

    Other Negative Aspects Of Oral Contraceptive Pills

    • As it should be taken timely, it may cause difficulties in remembering to take it at the same time daily
    • OC pills may not protect against sexually transmitted diseases compared to barrier methods like condoms. But, it can make the mucus of the cervix thick so that pathogens cannot pass to the uterus and cause infection.
    • It can cause break through periods sometimes when their timings are interfered.
    • To Conclude

      Oral contraceptive pills should be taken only after consulting a medical expert.

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