Progestin only pill

How They Work; Pros and Cons

Composition

Norethindrone 0.35mg (Micronor 28).

Mechanism of Action

Endometrial suppression and thickening of cervical mucus is the primary mechanism of action of the POP.
Ovulation is also inhibited in 60 percent of women taking the POP.

Dosage

The POP is taken daily and at the same time of day (within three hours) to ensure a reliable effect. The pills should be started on the first or second day of the menstruation cycle, and then daily (nonstop) thereafter. There is no pill free interval. All twentyeight pills in a package contain active medication.

Advantages

1. No absolute contraindications- the POP may be used in women with contraindications to the combined oral contraceptive pill (OCP) such as thromboembolic disease and myocardial disease 
2. May be used in women over 35 who smoke, during breastfeeding and if the combined pill is discontinued before major surgery 
3. No estrogen- related side effects 

Disadvantages/Side Effects

1. Intermenstrual bleeding 
2. Functional ovarian cysts 
3. Amenorrhea 
4. Headache 

Efficacy

Progestin-only pills have a theoretic contraceptive effectiveness of 90 to 99 percent. The failure rate is lowest in highly motivated women. The effectiveness drops off dramatically with missed or delayed pills. The Pearl Index is 0.3-4 (failure rate for 100 women using the method for one year).

Contraindications/Poor candidates

Absolute

None except known or suspected pregnancy or the presence of undiagnosed vaginal bleeding.

Relative

1. Any serious side effect occurring on the OCP and not clearly due to estrogen. 
2. When pregnancy would be devastating to a woman with underlying medical or obstetrical problems. 

Follow-up

Early on to dispel concerns.Three months has been the traditional time for the first follow-up visit however an earlier follow-up appointment may improve adherence especially in first time users.

Missed Pills

If even one pill is forgotten or vomited, a back-up method of contraception (condoms) must be used for at least 48 hours and some experts recommend a backup method for a full week until the hostile mucus effect has been restored. The user should continue to take her tablets as prescribed.