Most women find that combined hormonal contraception (CHC) provides reliable cycle control.

Indeed the combined oral contraceptive pill (COCP) is often prescribed for the management of menstrual disorders such as menorrhagia and dysfunctional uterine bleeding.¹

However, although new formulations with low doses of oestrogen offer health benefits, they may provide less satisfactory cycle control.² The risk of bleeding may also be related to the dose and type of progestogen. Unfortunately, methodological differences between studies have also made it difficult to compare rates of breakthrough bleeding between different preparations.¹

Epidemiology

Irregular bleeding whilst taking combined hormonal contraception (CHC) is a common problem with up to 30% of women experiencing breakthrough bleeding or spotting during the first cycle of treatment.³ Such bleeding occurs unpredictably⁴ and may cause significant disruption and anxiety for users.⁵ Irregular bleeding is thus one of the most common reasons for discontinuation of CHC.⁶

Mechanism of action

Normal endometrial maturation depends on complex interactions between oestrogen and progesterone. Combined hormonal contraception (CHC) provides a continuous supply of oestrogen and progestogen to the endometrium. The low dose of oestrogen in modern CHCs is insufficient to maintain endometrial integrity³ and the opposing effect of progestogen promotes atrophy of glands and stroma. The resulting endometrium is thin, fragile and prone to bleeding.¹

Contraceptive efficacy

No relationship has been identified between serum steroid levels and bleeding.⁷ In the absence of missed or late pills, vomiting or drug interactions, reduced contraceptive efficacy has not been proven.⁸

Factors which influence bleeding

Patient factors¹

• Poor compliance with medication is the most likely cause of irregular bleeding.
• Cigarette smoking has anti-oestrogenic properties and may affect cycle control.

Combined hormonal contraception (CHC) formulation factors

• Combined oral contraceptive pills (COCPs) containing only 20 micrograms of ethinylestradiol (EE) cause more disrupted bleeding patterns than those containing higher doses.⁹
• Monophasic and biphasic formulations provide similar cycle control.¹⁰
• Triphasic formulations may offer better cycle control.
• First-generation progestogens, e.g. norethisterone, provide poorer cycle control than second-generation (levonorgestrel) and third-generation progestogens.¹¹
• Of third-generation progestogens, gestodene may afford better cycle control than desogestrel.¹¹
• CHC patches are associated with more irregular bleeding than COCPs during initial treatment, but rates are similar after three months of use.¹²

Management of breakthrough bleeding

Clinical assessment

Take a clinical history to assess:

• The woman's concerns.
• Correct use of the method (e.g. pill taking, patch use), use of interacting medication, illness altering absorption of orally administered hormones.
• Other symptoms (e.g. pain, dyspareunia, abnormal vaginal discharge, heavy bleeding, postcoital bleeding).
• Exclude sexually transmitted infections.
• Check cervical screening history.
• Consider the need for a pregnancy test.

Recommendations to prevent bleeding

• Use combined oral contraceptive pills (COCPs) containing 30 micrograms of ethinylestradiol (EE) combined with a second-generation progestogen as first-choice. Data do not support increasing the dose of oestrogen in women already using a 30 microgram COCP. Nevertheless, increasing the dose of EE to 35 micrograms may improve bleeding patterns for some women.
• There is no evidence that starting combined hormonal contraception (CHC) mid-cycle reduces the incidence of bleeding.¹³

Recommendations to reduce bleeding

Other considerations

Although CHC is a common cause of irregular bleeding, other unrelated causes must also be considered such as:³

• Chlamydia or other sexually transmitted infections.
• Intrauterine or ectopic pregnancy.⁸
• Endometrial or cervical polyp.³ The role of uterine polyps, fibroids or ovarian cysts as a cause of unscheduled bleeding is limited. Nevertheless, for all women using hormonal contraception with unscheduled bleeding, if such a structural abnormality is suspected, a transvaginal ultrasound scan and/or hysteroscopy may be indicated.¹⁴
• Cervical cancer.
• Endocrine abnormalities such as hypothyroidism, hyperthyroidism, hyperprolactinaemia.
• Bleeding disorders.³

Document references

1. No authors listed; Ovarian and endometrial function during hormonal contraception. Hum Reprod. 2001 Jul;16(7):1527-35. [abstract]
2. Kaunitz AM; Enhancing oral contraceptive success: the potential of new formulations. Am J Obstet Gynecol. 2004 Apr;190(4 Suppl):S23-9. [abstract]
3. Schrager S; Abnormal uterine bleeding associated with hormonal contraception. Am Fam Physician. 2002 May 15;65(10):2073-80. [abstract]
4. WHO (HRP); Rogers A. Progress in Reproductive Health Research. How does progestogen cause endometrial bleeding. 1999.
5. Hickey M, Fraser IS; Surface vascularization and endometrial appearance in women with menorrhagia or using levonorgestrel contraceptive implants. Implications for the mechanisms of breakthrough bleeding. Hum Reprod. 2002 Sep;17(9):2428-34. [abstract]
6. Ansbacher R; Low-dose oral contraceptives: health consequences of discontinuation. Contraception. 2000 Dec;62(6):285-8. [abstract]
7. First Prescription of Combined Oral Contraception, Faculty of Family Planning and Reproductive Health Care (2007)
8. Contraception - combined hormonal methods, Prodigy (Sept 2007)
9. Gallo MF, Nanda K, Grimes DA, et al; 20 mcg versus>20 mcg estrogen combined oral contraceptives for contraception. Cochrane Database Syst Rev. 2005 Apr 18;(2):CD003989. [abstract]
10. Van Vliet HA, Grimes DA, Helmerhorst FM, et al; Biphasic versus monophasic oral contraceptives for contraception. Cochrane Database Syst Rev. 2006 Jul 19;3:CD002032. [abstract]
11. Maitra N, Kulier R, Bloemenkamp KW, et al; Progestogens in combined oral contraceptives for contraception. Cochrane Database Syst Rev. 2004;(3):CD004861. [abstract]
12. Norelgestromin/ethinyl oestradiol transdermal contraceptive system (Evra), New Product Review, Faculty of Family Planning and Reproductive Healthcare (2003)
13. Yeshaya A, Orvieto R, Kaplan B, et al; Flexible starting schedule for oral contraception: effect on the incidence of breakthrough bleeding and compliance. Eur J Contracept Reprod Health Care. 1998 Sep;3(3):121-3. [abstract]
14. Management of Unscheduled Bleeding in Women Using Hormonal Contraception, Faculty of Sexual and Reproductive Healthcare (2009)
15. Van Vliet HA, Grimes DA, Helmerhorst FM, et al; Biphasic versus triphasic oral contraceptives for contraception. Cochrane Database Syst Rev. 2006 Jul 19;3:CD003283. [abstract]
16. Wagstaff AJ; Continuous-use ethinylestradiol/levonorgestrel 20microg/90microg: as an oral contraceptive. Drugs. 2007;67(16):2473-7; discussion 2478-9. [abstract]
17. Coffee AL, Sulak PJ, Kuehl TJ; Long-term assessment of symptomatology and satisfaction of an extended oral contraceptive regimen. Contraception. 2007 Jun;75(6):444-9. Epub 2007 Mar 23. [abstract]

Internet and further reading

• Selected practice recommendations for contraceptive use, World Health Organization, 2004
• Department of Health; Revised guidance for health professionals on the provision of contraceptive services for under 16s (July 2004).