The birth control pill is a form of birth control that has been available on the market since the 1960s.
In the beginning, the pills contained large amounts of the hormones progesterone and estrogen, which was responsible for the high rate of side effects, including some serious ones, such as thrombosis, stroke and cardiovascular diseases.
Since the 1980s, however, the amount of hormones present in the birth control pill has been progressively decreasing, especially the concentration of estrogens. The current goal of the scientific community is to obtain effective contraception with a minimum amount of hormones.
This search for oral contraceptives that contain the least possible amount of hormones without losing contraceptive efficacy has given rise to the so-called minipill, a contraceptive pill composed only of the hormone progesterone. The minipill, unlike traditional oral contraceptives, does not contain the hormone estrogen in its formula.
In this article we will exclusively address the minipill, including explanations of the commercially available options, forms of use, indications, and side effects.
What is the minipill?
As mentioned in the introduction of this article, the minipill is a birth control pill composed exclusively of the hormone progestin, which is the synthetic form of progesterone.
The logic behind the development of the minipill is to allow women to have a birth control pill that is effective, but does not contain the hormone estrogen, which is responsible for most of the unwanted side effects of traditional pills.
there are 3 different minipill formulations, each with a different progestin:
- Norethisterone 0.35 mcg (trade names: Norestin, Micronor).
- Desogestrel 0.075 mcg (trade names: Cerazette, Nactali, Juliet, Kelly).
- Linestrenol 0.5 mcg (brand names: Exluton).
Except for Linestrenol, the other two progestins can also be found in traditional contraceptives, along with estrogen, such as Mesigyna (estradiol + norethisterone) and Femina (ethinyl estradiol + desogestrel), for example.
How it works?
The minipill exerts its contraceptive effect in several ways. Like the estrogen and progesterone pill, the minipill also works by preventing ovulation. However, this suppressing effect on ovulation is much weaker than traditional contraceptives.
The minipill is successful as a contraceptive method because it has at least two more effects on the female reproductive system. The progesterone pill thickens the cervical mucus, making life difficult for sperm, which cannot reach the tubes to find the egg.
Also, there is a third effect. Even if the woman ovulates, even if the sperm manages to reach the egg to fertilize it, the minipill also acts by making the inner wall of the uterus thinner, making the implantation of this possible fertilized egg difficult, thus preventing the occurrence of a pregnancy.
Therefore, for the minipill to fail, it takes at least 3 consecutive failures in its mechanism of action. When taken correctly, the success rate is as high as 99%.
In practice, however, the minipill’s success rate is around 92%. The problem is not exactly the failure of the progesterone pill, but rather the failure of patients to take the drug correctly.
As we’ll see below, for the minipill to work properly, it requires a little more discipline in terms of timing than traditional pills.
Who should take?
The minipill can be taken by virtually all women seeking contraception. However, it is especially helpful for those women who are most at risk for side effects caused by estrogen. Examples of this situation are women over 35, smokers, hypertensive, overweight, diabetics, migraine sufferers, women at higher risk of thrombotic events, etc.
The minipill does not increase cardiovascular risk or facilitate the development of thrombosis. It also doesn’t cause migraines, doesn’t usually alter libido or cause weight gain.
The minipill can also be used during breastfeeding as it does not interrupt milk production and does not harm the baby. We will explain later on how lactating women should take it.
The progesterone pill should not be indicated for women who have problems with lack of discipline with medications. If you are one of those people who keeps forgetting the time of medicine or who often fails to take the conventional pill, the minipill is not a good option. In these cases, the IUD is a much better alternative
How to take?
The minipill can be started at any time of the cycle, however, the best option is for the pack to be started on the first day of the cycle, that is, on the first day of menstruation. If the progesterone pill is started on the first day of the cycle, its contraceptive effect is immediate, and there is no need to use a complementary contraceptive method, such as a condom.
If, on the other hand, the minipill is started on any other day of the cycle, it is ideal to use a condom for the first 7 days if you have sex. It is likely that from the 2nd day on the pill you will already be protected, but in general, for safety, we suggest a 7-day break.
The minipill must be taken uninterruptedly. Each pack has 28 pills and there is no pause between one pack and another. The minipill must be taken at the same time each day. That’s its main drawback. A simple delay of more than 3 hours is enough for the pill to lose its protective effect.
What to do if the woman forgets to take the minipill at the correct time
If a woman forgets to take the minipill at the correct time, she should take it as soon as she remembers. The pill must always be at hand, preferably in the bag so that it can be taken at any time, even if the woman is away from home. If forgetfulness is longer than 3 hours, in the next 2 days any sexual intercourse must be done with a condom. After 48 hours, the mucus becomes thick enough to stop the sperm from progressing.
If the woman vomits within the first 3 hours after taking her daily dose, for safety reasons, proceed as a missed dose. The woman must take the pill again and give her 2 days of safety margin for her to take action again. Diarrhea is usually not a problem, unless it is very intense, with several stools a day. In this case, the minipill must be stopped until frame resolution.
How to switch from the conventional pill to the minipill
A woman who wants to change her contraceptive method must do so the day after the last pill in the pack. The patient finishes her traditional contraceptive pack today and starts the minipill tomorrow. This way there is no interruption of the contraceptive effect.
If the contraceptive is injectable, the minipill should be started on the day the next injection was due. If it is an IUD, the minipill must be started on the day of device removal.
How to take the minipill while breastfeeding
Breastfeeding women can start the minipill after the 6th week postpartum. In general, there is no ovulation during this period and not using a minipill in the first days minimizes any hormonal influence in the initial phase of milk production. After milk production is fully established, the minipill does not interfere at all.
In women who are not exclusive breastfeeding and alternate feedings with artificial formulas, the risk of ovulation before the first 6 weeks is greater, so the minipill should be started from the 3rd week on.
How to take the minipill after childbirth
If you are not breastfeeding, the minipill can be started the day after delivery. As women do not ovulate for the first 3 weeks after giving birth, the minipill can be safely started anytime within this range. If the progesterone pill is started within the first 21 days after delivery, no complementary contraceptive method is needed. However, if the minipill is started after day 21, an additional method should be used for 2 to 7 days.
How to take the minipill after an abortion
The minipill should be started the day after an abortion. No complementary contraceptive method is needed.
Do antibiotics cut the minipill’s effect?
As with estrogen and progesterone pills, antibiotics don’t cut the minipill’s effect. The only exception is an antibiotic called rifampicin (or its derivative rifabutin).
The main side effect of the minipill is menstrual irregularity. In some women there may be isolated blood loss throughout the cycle or menstrual cycles with a completely unpredictable schedule. Menstrual irregularities are more common in those women who do not take the minipill at the same time each day.
Most women who take the progesterone pill continue to menstruate, usually on a regular basis, but the flow is reduced. There are cases, however, of increased menstrual flow with the use of the progesterone pill.
Menstruation disorders are the main complaint of minipill users.
Another possible side effect is acne. This effect is very individual, but in women who already have problems with acne, the minipill can aggravate the condition.
- Progestin-only pills (POPs) for contraception – UpToDate.
- Progestin-Only Hormonal Birth Control: Pill and Injection – American College of Obstetricians and Gynecologists.
- Estrogen-free oral hormonal contraception: benefits of the progestin-only pill – Women’s health.