title: Missed pills: frequency, reasons, consequences and solutions.
abstract: OBJECTIVE
  Oral hormonal contraception is an effective contraceptive method as long as regular daily intake is maintained. However, a daily routine is a constraint for many women and can lead to missed pills, pill discontinuation and/or unintended pregnancy. This article describes the frequency of inconsistent use, the consequences, the risk factors and the possible solutions.
  
  
  METHODS
  The article comprises a narrative review of the literature.
  
  
  RESULTS
  Forgetting one to three pills per cycle is a frequent problem among 15-51% of users, generally adolescents. The reasons for this are age, inability to establish a routine, pill unavailability, side effects, loss of motivation and lack of involvement in the initial decision to use oral contraceptives. The consequences are 'escape ovulations' and, possibly, unintended pregnancy. Solutions are either to use a long-acting method or, for women who prefer to take oral contraceptives, use a continuous or long-cycle regimen to reduce the risks of follicular development and thus the likelihood of ovulation and unintended pregnancy. A progestogen with a long half-life can increase ovarian suppression.
  
  
  CONCLUSIONS
  For women deciding to use oral contraceptives, a shortened or eliminated hormone-free interval and a progestogen with a long half-life may be an option to reduce the negative consequences of missed oral contraceptive pills.
authors.affiliation: a Department of Obstetrics and Gynaecology , APHP Tenon Hospital, Pierre and Marie Curie University , Paris , France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Chabbert-Buffet
authors.affiliation: b Independent Researcher , Paris , France.
authors.forename: Christian
authors.initials: C
authors.lastname: Jamin
authors.affiliation: c Department of Obstetrics and Gynaecology , Araba University Hospital , Vitoria-Gasteiz , Spain.
authors.forename: Iñaki
authors.initials: I
authors.lastname: Lete
authors.affiliation: d Department of Obstetrics and Gynaecology , Infanta Sofía University Hospital , San Sebastián de los Reyes, Madrid , Spain.
authors.forename: Paloma
authors.initials: P
authors.lastname: Lobo
authors.affiliation: e Department of Clinical, Surgical, Diagnostic and Paediatric Sciences , Research Centre for Reproductive Medicine, Gynaecological Endocrinology and Menopause, IRCCS San Matteo Foundation, University of Pavia , Pavia , Italy.
authors.forename: Rossella E
authors.initials: RE
authors.lastname: Nappi
authors.affiliation: f Department of Obstetrics and Gynaecology , Citadelle Hospital, University of Liège , Liège , Belgium.
authors.forename: Axelle
authors.initials: A
authors.lastname: Pintiaux
authors.affiliation: g Department of Gynaecology and Gynaecological Oncology , Vienna General Hospital , Vienna , Austria.
authors.forename: Günther
authors.initials: G
authors.lastname: Häusler
authors.affiliation: h Gynmed Outpatient Clinic for Pregnancy and Family Planning , Vienna , Austria.|i Department of Women's and Children's Health , Karolinska Institutet , Stockholm , Sweden.
authors.forename: Christian
authors.identifier: http://orcid.org/0000-0001-6451-7349
authors.initials: C
authors.lastname: Fiala
mesh_terms: D000293:Adolescent; D000328:Adult; D003267:Contraception / Q000379:methods / Q000523:psychology / Q000706:statistics & numerical data*; D003278:Contraceptives, Oral, Hormonal / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D055118:Medication Adherence / Q000523:psychology; D034445:Ovulation Inhibition / Q000187:drug effects / Q000523:psychology; D011247:Pregnancy; D049168:Pregnancy, Unplanned / Q000187:drug effects; D011372:Progestins / Q000627:therapeutic use; D055815:Young Adult; D016903:Drug Monitoring
chemical_list: D003278:Contraceptives, Oral, Hormonal; D011372:Progestins
keywords: Compliance; efficacy; half-life; hormone-free interval; missed pill; nomegestrol acetate; non-compliance; progestogen; regimen