Understanding Birth Control Pills | Gleneagles Hospitals
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Women’s Health

Understanding Birth Control Pills

26 March 2024 · 4 mins read

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Understand the types, effectiveness, benefits, and side effects of birth control pills.

Birth control pills are effective oral contraceptives containing synthetic versions of hormones that work together to prevent pregnancy when taken correctly and consistently. Millions of women worldwide use birth control pills to prevent unwanted pregnancies.

This informational guide will explore the types of birth control pills available, how they work, and other aspects to determine if they are a suitable choice for you.

Types of Birth Control Pills

Combination pills

Combination pills contain a combination of synthetic oestrogen and progestin hormones. They prevent ovulation and create unfavourable cervical and uterine environments to obstruct fertilisation and prevent pregnancy.

Types of combinations pills:

  • Monophasic pills contain the same dose of hormones in each active pill and are used in 1-month cycles. They come in packs of 21 days with a 7-day break (21/7) where either no pill or a placebo is taken. This results in a withdrawal bleed. An alternative would be the 24/4 regimen with four days of placebo or low-dose oestrogen.
  • Phasic pills contain different doses of oestrogen and progestin for a 1-month cycle meant to mimic hormonal fluctuations during the menstrual cycle.
  • Extended-cycle pills aredesigned to be taken for up to 3 months (84/7), after which there will be a 7-day interval with either a placebo or no pills. The usage of these pills results in periods occurring only four times a year.

Progestin-only pills

Progestin-only pills or "minipill" is used by those who cannot or prefer not to use contraceptives with oestrogen. The main progestins are norethindrone and drospirenone.

A pack of progestin-only pills contains 28 pills. Depending on the type of progestin-only pill, the required timing is either a 3-hour window or a 12-hour window. It is essential to take the pill consistently at approximately the same time each day to ensure its effectiveness.

Progestin-only pills prevent pregnancy by suppressing ovulation, inhibiting sperm migration, thinning the endometrium, and thickening the cervical mucous.

A progestin-only pill is safe to be used when breastfeeding.


Being on birth control pills can make you miss your period or have lighter periods. This is due to the alterations of hormones, which can affect the menstrual cycle.

However, missing a period while on the pill does not necessarily indicate pregnancy. Other factors that can contribute to a missing period include strenuous exercise, changes in diet, stress, and having other health conditions.

Effectiveness and Benefits of Birth Control Pills

Birth control pills are excellent at preventing unwanted pregnancy when taken correctly and consistently daily. You can remember to maintain your consistency in taking the pills by using a tracker like a birth control app to schedule reminders.

In addition to preventing pregnancy, birth control pills have several other benefits for women, such as treating acne, alleviating premenstrual syndrome (PMS) symptoms, minimising the risk of infections in the ovaries, fallopian tubes, or uterus, reducing the risk of endometrial and ovarian cancer, and preventing anaemia (iron deficiency).

Side Effects of Birth Control Pills

Like all medications, birth control pills can cause side effects in some women. However, several women also report experiencing no symptoms at all.

The most common side effects of birth control pills include the following:

  • Nausea
  • Breast tenderness
  • Irregular or sporadic bleeding or spotting
  • Amenorrhea (absence of menstruation)
  • Headaches
  • Worsening of migraines
  • Mood changes – depression, anxiety, or irritability
  • Weight gain – the hormones in birth control pills can cause fluid retention, leading to temporary weight gain. This is usually short-term and goes away on its own.

Although rare, some risks include deep vein thrombosis, high blood pressure, stroke, heart attack, breast cancer, and cervical cancer.

Your doctor may recommend switching to a different birth control pill if the side effects have not ceased after a few months.

Make an Appointment at Gleneagles Hospitals

When used consistently each day, the birth control pill is a fairly effective method of preventing pregnancy. Before deciding on the brand of pill that works best for you, discuss your queries and concerns regarding the pill with a healthcare professional.

Get in touch with us to book an appointment with our team of gynaecologists today, or find out more about our Obstetrics and Gynaecology Services at your nearest Gleneagles Hospital.


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