Viewpoint - Depot progestogen

Progestogen injectables should not be overlooked as a contraceptive option, explains Dr Diana Mansour.

Depot medroxyprogesterone acetate (DMPA) is licensed for long-term contraceptive use.

No additional contraceptive measures are required if it is started within the first five days of the menstrual cycle. It can be given any time in the cycle as long as the clinician is reasonably sure that the woman is not pregnant, however an additional contraceptive method or abstinence is required for a further seven days.1

Ovarian cysts: DMPA reduces incidence due to inhibited ovulation (SPL)

Contraceptive action
DMPA inhibits ovulation through suppression of luteinising hormone and to a certain extent follicle-stimulating hormone.

This progestogen also causes secretory changes in the endometrium preventing blastocyst implantation, increases cervical mucus viscosity inhibiting sperm penetration, and adversely affects sperm motility and function. It is therefore highly effective when given regularly, with less than four women per 1,000 becoming pregnant over a two-year period.1

There is also no evidence of increased risk of congenital abnormalities if it were to fail.2

Advantages
There are a number of advantages to DMPA. It is safe, convenient, non-intercourse related requiring little user dependence and can be used by breastfeeding women. It is discrete and free from estrogen-associated risks such as venous thromboembolism.

DMPA has a number of important non-contraceptive benefits, including an improvement of symptoms in women who suffer from cyclical complaints, ovulation pain and painful, heavy periods.

NICE has supported the use of DMPA in women suffering with heavy menstrual bleeding3 because amenorrhoea rates are high with this method - 55 per cent of users are bleed-free at 12 months and 68 per cent at two years.2

It is also useful in women with sickle cell disease as there is evidence suggesting a reduction in sickle cell crises.4 Although DMPA does not prevent the acquisition of STIs, like other hormonal contraceptives it may provide some protection against upper genital tract sequelae such as pelvic inflammatory disease.

The risk of extra-uterine pregnancies and development of functional ovarian cysts is reduced because DMPA inhibits ovulation.

There is some evidence that fibroid formation and growth is less common in long-term users5 with endometrial cancer risk reduced fivefold. The protective effect lasts for at least eight years after cessation.6

Disadvantages
Approximately one in two women stop using DMPA within the first year of use,1 with between 30-40 per cent citing bleeding problems as the main reason for discontinuation.

On stopping DMPA it may take 6-12 months before a regular cycle is re-established. Amenorrhoea may be very acceptable after careful pretreatment counselling but frequent, irregular and prolonged bleeding will lead to dissatisfaction.

Within the first three months up to 33 per cent of women may complain of prolonged bleeding (>10 days) but this decreases to 12 per cent at 12 months.2

DMPA use is associated with weight gain and this should be discussed pre-treatment. There is also comparative evidence demonstrating that DMPA users gain more weight than women using a levonorgestrel intrauterine system or copper intrauterine device.7

DMPA is safe to use in obese women with no reported increase in serious adverse events or loss of efficacy.8

Concerns have been raised relating to the use of DMPA and its effects on bone mineral density. Misinformation and inaccurate interpretation of data by 'experts', has generated fear in healthcare professionals. This has led to reduced prescribing of DMPA.

The Committee on Safety of Medicines gave clear advice in 2004 (see box overleaf).9

Fertility
A common myth is that DMPA causes 'permanent infertility'. This is untrue, however there may be a delay in return to normal fertility due to persistence of this depot progestogen.

The mean time to conception has been reported to be nine months after the last DMPA injection (the true delay therefore being 5.5 months), with 78 per cent of couples having conceived at one year and 92 per cent at two years after stopping the injection.10 Pregnancies have been reported as early as 14 weeks after the last injection. The mean time to ovulation has been reported as 5.3 months.2

Thus, even if amenorrhoea persists, another method of contraception should be used immediately to avoid an unplanned pregnancy.

Conclusion
From appraising the evidence, DMPA is still a safe, highly effective, reversible contraceptive method. Unfortunately it has been subject to adverse publicity and misinterpretation of methodologically flawed studies.

This has resulted in clinicians losing confidence and failing to offer true contraceptive choice.

  • Dr Mansour is consultant in community gynaecology and reproductive health care in Newcastle upon Tyne CSM advice on DMPA
  • In adolescents, DMPA may be used as first-line contraception but only after other methods have been discussed with the patient and discounted.
  • In women of all ages, careful re-evaluation of risks and benefits should be carried out for those who wish to continue use for more than two years.
  • In women with significant lifestyle and/or medical risk factors for osteoporosis, other methods of contraception should be considered.

References

1. Long-acting reversible contraception, NICE, Clinical Guideline 30, London, 2005.

2. Depo-Provera Patient Information Sheet. Pharmacia Ltd. November 2004.

3. Heavy menstrual bleeding, NICE Clinical Guideline 44, London, 2007.

4. De Ceular K, Gruber C, Hayes R et al. Lancet 1982; 2: 229.

5. Lumbiganon P, Rugpao S, Phandhu-fung S et al. Br J Obstet Gynaecol 1996;103:909-14.

6. WHO. Collaborative Study of Neoplasia and Steroid Contraceptives. Int J Cancer 1991; 49: 186-190.

7. Yela D A, Monteiro IM, Bahamondes LG et al. Rev Assoc Med Bras 2006; 52: 32-6.

8. Bonny A E, Ziegler J, Harvey R et al. Arch Pediatr Adolesc Med 2006; 160: 40-5.

9. Committee on Safety of Medicines. MHRA, November 2004 http://medicines.mhra.gov.uk accessed 23 March 2009.

10. Pardthaisong T. J Biosoc Sci 1984; 16: 23-34.

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