Contraception - General Overview

Family planning is, arguably a pressing global concern.
In the UK, population is officially projected to rise from 60.2 million (mid-2005) to 70.7 million in 2074 - another one and a half Londons in less than a lifetime.¹
The United Nations predict that world population will rise from today's 6.6 billion to 9.2 billion by 2050. This represents a growth rate of 78 million a year - a population almost the size of Germany's.
Whilst considering and respecting different religious and cultural values, we should strive to ensure that every woman, who wishes to, has access to safe and effective contraception.

Two types of contraceptive failure:

• User failure; when the contraceptive method not being used properly
• Method failure; pregnancy results even though the contraceptive method was used properly

User failure rates are much higher than method failure rates, especially in first year of use.

The combined oral contraceptive pill is a highly effective form of contraception³ and used by 24% of women aged 16 to 49 years in the UK to control fertility.⁴
The COCP contains a combination of synthetic oestrogen and progestogen. They have been classified into first, second and third generation preparations reflecting their hormonal content and period of development. All current brands contain 20-40mcg of oestrogen.

Mode of action

The COCP prevents conception by acting on:⁵

• The hypothalamic-pituitary-ovarian axis, to suppress synthesis and secretion of follicle-stimulating hormone and the mid-cycle surge of luteinising hormone, thus inhibiting the development of ovarian follicles and ovulation
• Cervical mucus to prevent penetration of sperm
• The endometrium to inhibit blastocyst implantation

Work by preventing ovulation, thickening cervical mucus and reducing endometrial receptivity.
This combination is now also available as a transdermal combined contraceptive (a patch), which appears to be equivalent to COCP.⁶

Benefits

• Highly effective, easy to reverse and convenient to use
• Can bring relief from menstrual problems
• Reduces incidence of benign breast disease, ovarian cysts, ovarian cancer and endometrial cancer⁷

Problems

• Side effects e.g. breakthrough bleeding, breast tenderness, acne, mood swings
• Increased risk of venous thromboembolism; increased c/f non-users, but much less than pregnancy⁵
• Increased risk of MI; increased risk most pronounced in women with risk factors e.g. smoking, hypertension, diabetes
• Increased risk of stroke; 2x that of non-users overall, but higher in women with hypertension and smokers
• Slightly increased risk of breast cancer; as incidence of breast cancer under age 40 years is low, absolute risk in young women is small
• Increased risk of cervical cancer; but may be related to other factors e.g. number of sexual partners, non-barrier use during intercourse
• Increased risk of primary liver cancer; only with high dose oestrogen and absolute risk is very small
• Increased overall mortality despite careful selection and follow-up

Contain one of the following: norethisterone, ethynodiol diacetate (metabolised to norethisterone) or levonorgestrel. Desogestrel (Cerazette) is a newer progestogen that is converted in the body to the active form of etonogestrel. It tends to be metabolically "cleaner" than the older progestogens and appears very promising. Amenorrhoea is more likely to occur, being present in 50% of desogestrel users compared with 10% of those taking levonorgestrel in one study. Failure rate was also lower with desogestrel but the numbers were so small that confidence intervals were very wide and there was considerable overlap. The feature of this formulation that is likely to have the greatest impact is the 12 hours window for "forgetfulness" rather than just 3 hours.

Mode of action

Work by inhibition of ovulation - with desogestrel this occurs in 97% of cycles,⁸ transport of the ovum is delayed, the cervical mucus becomes more viscous and impenetrable to sperm and the endometrium is unsuitable for implantation.

Benefits

• Reliable if taken correctly, easily reversible and convenient to use
• Avoids cardiovascular risks of oestrogen
• Can often be used by women with contraindications to COCP
• Can be used during breast feeding

Problems

• Menstrual problems such as amenorrhoea and breakthrough bleeding
• Needs to taken at the same time daily
• Increase risk of functional ovarian cysts (30% increased risk) and possibility of breast cancer (similar to COCP)
• Typically used for women who do not tolerate a COCP or for whom they are contraindicated

Products available in the UK:

• IM medroxyprogesterone acetate (Depo-Provera); provides contraception for 12 weeks for women who have been advised of the chances of menstrual disturbance and the possibility of a delay in return to full fertility.
• IM norethisterone oenanthate (Noristerat); licensed for short-term use with 2 injections only for women who need highly reliable contraception without chance of user error.

Mode of action

They contain long acting progestogen that prevent ovulation, thicken cervical mucus and reduce uterine receptivity.

Benefits

• Very effective and convenient
• Can be used during breast feeding

Problems

• Cannot be stopped
• Menstrual irregularities are common
• Weight gain; occurs in majority of women using Depo-Provera
• Delayed returned of fertility; can be >1 year with Depo-Provera
• Possible risk of depression; not clearly shown yet
• Possible increased risk of breast cancer; not clearly shown yet
• Reduced bone mineral density⁹

This is a long acting reversible contraceptive. Etonogestrel contained in a rod is released slowly into the systemic circulation following subdermal insertion in the upper arm.
Implanon™ is now the only contraceptive implant on the UK market.¹⁰ It is a 4cm flexible rod containing 68mg etonogestrel (a progestogen). Implanon™ must be removed after 3 years when it can then be replaced.

Mode of action

The main mechanism of action of Implanon™ is to inhibit ovulation. It also thickens the cervical mucus, inhibiting the passage of sperm to the uterus, as well as thinning the endometrium, preventing implantation were an egg to be fertilised.²

Benefits

• Highly effective with very few pregnancies reported
• Long duration of action
• Reversible
• Very convenient

Problems

• Irregular bleeding; common in first year but declines thereafter
• Weight gain; 20% of women show 10% increase

The IUCD is a safe and effective method of contraception. Although use in the UK has increased in recent years, only 5% of contraceptive users aged 16-49 years currently use an IUD.¹¹ There are 150 million users of the IUCD worldwide. The majority are in China. They are ideal for a woman in her forties, with children. Recent evidence suggests that the latest banded copper IUCDs are better than the combined oral contraceptive and as effective as reversible sterilisation.^12,13The Gold standard IUCD is the banded T-safe copper 380A. All should only be fitted by properly trained personnel who are fitting IUCDs regularly i.e. >50/year.
They have a duration of action of 5-10 years if contain 380mm copper, or until contraception is no longer required in later years of reproductive life.
IUCDs have a monofilament thread to permit checking of presence and to allow removal.

Mode of action

They work predominantly by inducing an inflammatory response in the uterus which affects the viability of sperm and ova. They prevent fertilisation and implantation.

Benefits

• Highly effective, reversible and convenient
• Effective directly following fitting

Problems

• Spotting and bleeding between periods. 50% patients request removal within 5 yrs.
• Increased blood loss and more painful periods especially during first few cycles
• Displacement or expulsion; 37/1000 insertions become expelled usually during first 3 months and may go unnoticed
• Increased risk of PID; in first 20 days only and women should be screened before insertion
• Uterine perforation; 1/1000 insertions
• Ectopic pregnancy; risk is 1 in 20 if pregnant with IUCD in-situ, so absolute risk is very low

The LNG-IUS has been licensed as a contraceptive in the UK since May 1995. Recent National Statistics suggest the LNG-IUS is used by only 1% of women aged 16-49 years who are currently using a method of contraception.¹⁴ The LNG-IUS now also has a licence for the management of idiopathic menorrhagia and may therefore be used by women who do not require contraception.
Only one system available (Mirena®) a T-shaped device. It can be effective for 5 years or until contraception is no longer required.

Mode of action

This is mainly by reducing endometrial growth and preventing implantation.

Benefits

• Very effective, convenient and reversible
• Reduces blood loss and dysmenorrhoea
• May reduce risk of PID compared with normal IUDs
• Does not significantly interact with other drugs as action is principally local.

Problems

• Menstrual irregularities are common in first few months, with 60% patients requesting removal within 5 years.
• Typical progestogenic side effects
• Dysfunctional ovarian cyst, but usually resolves spontaneously
• Need for fitting; larger than normal IUDs and may require cervical dilatation with local anaesthesia.

Their popularity as forms of contraception have declined with the availability of more effective methods and with awareness of the need to protect against sexually transmitted infections.
Diaphragms are thin, dome-shaped devices made of latex or silicone and range in size between 55 and 100mm. Diaphragms should lie diagonally between the posterior fornix and behind the pubic bone. Caps are smaller than diaphragms fitting closely over the cervix. Both should be used with spermicides. They come in 3 styles:

• Flat spring; for women with normal vaginal muscular strength
• Arcing spring; for women with poor vaginal muscular strength
• Coil spring; may cause less discomfort in some women

Mode of action

Caps and diaphragms form a physical barrier, preventing entrance of sperm to the cervix.¹⁵

Benefits

• Insertion before intercourse can allow spontaneity
• May offer some protection against cervical carcinoma, STD and PID

Problems

• Women needs to be well motivated and careful in its use
• Spermicides can cause local reaction
• UTI with diaphragms

The female condom has been available in Great Britain since 1992. It is made of soft pliable polyurethane, pre-lubricated and has 2 flexible rings.

Mode of action

This is a barrier method.

Benefits

• No known side effects
• Helps prevent STD and possibly reduces risk of cervical carcinoma
• Can be inserted prior to intercourse

Problems

• Needs careful insertion
• Can be pushed into vagina or bypassed
• May be uncomfortable

The only contraindication to the use of latex condoms is for people with sensitivity or allergy to latex proteins as risks generally outweigh benefits.¹⁶ Men and women with sensitivity to latex may use male or female polyurethane condoms or deproteinised latex male condoms.

Mode of action

This is a barrier method

Benefits

• Ready availability
• Protects against STD and may protect woman against cervical cancer

Problems

• Relatively expensive if purchased (free condom uptake at FPCs is low)
• Needs prior planning
• Lacks spontaneity
• Requires cooperation of both partners
• May reduce sensitivity
• Can break or slip off, although research shows failures due to breakage or slippage decrease with increasing experience of use.

Several methods available including calendar, temperature, cervical mucus and palpating the cervix. Also Persona device measures urinary estrone 3-glucuronide and LH.

Benefits

• No side effects
• Complies with religious practices of some patients

Problems

• Requires considerable commitment from both partners
• Unreliable with unpredictable cycles

Several groups of women have special requirements regarding contraception, they include:

• Contraception for the mature woman - >40 years old
• Women who are breast feeding
• Women who have migraine headaches
• Smokers
• Contraception for younger women
• Diabetic women