SEXUAL HEALTH
NEW CHOICES IN CONTRACEPTION
Yasmin
This was launched last year after a long period of advance publicity. Yasmin is a combined oral contraceptive pill that contains the usual oestrogen at a dose of 30 micrograms (the same as most other widely used pills), but a totally new progestogen, drospirenone.
The main claim for this pill is that it won't cause weight gain, so its launch was eagerly awaited by those women who have experienced weight gain on the pill, and those who have previously chosen not to take the pill because of worries about possible weight gain. Unfortunately, the situation is not quite as clear-cut as was suggested. Yasmin does perform better than other pills in respect of weight gain due to fluid retention. It doesn't, however, perform any better in respect of weight gain due to fat deposition.
Cerazette
This is a progesterone-only pill (POP, also known as the mini-pill) with a real difference. Trials have shown that it prevents ovulation in most users, if taken correctly. This gives it a failure rate comparable to the combined pill and Depo-Provera injection. Other POPs have a higher failure rate because they only inhibit ovulation in a proportion of users. In many users, their contraceptive action relates to a thickening of the cervical mucus, which prevents sperm penetration. This can lead to a failure rate of around 1-2%. Cerazette is taken in the same way as other POPs and has a similar side-effect profile.
Implanon
This is a small, flexible rod that is inserted just beneath the skin on the inside of the upper arm. It slowly releases a progestogen, which inhibits ovulation as well as thickening the cervical mucus. The contraceptive action lasts for up to three years, and so far, no pregnancies have been reported by its users.
Insertion of Implanon is very quick, but removal takes a little longer. Removal is performed under local anaesthetic. A small cut is made at one end of the rod and then it is pulled out. This doesn't usually take more than about three minutes. Implanon produces similar side effects to POPs, and in addition the insertion and removal of the rod may cause slight pain or skin irritation.
Mirena
This is a small, T-shaped piece of plastic that is impregnated with a progestogen. It is like a coil, but because it acts in a quite different way, it is referred to as an IUS (intra-uterine system) rather than an IUD (intra-uterine device).
The progestogen acts directly on the lining of the womb to make it very thin and unsuitable for a fertilised egg to implant. It also thickens the cervical mucus and can prevent ovulation in some women. Its failure rate is very low, and is comparable to the combined pill and sterilisation (less then 0.5 %). Once in place, it works for five years, and its reliability remains the same throughout. An additional advantage is that it makes the periods extremely light, and some women find that their periods stop altogether while using it.
Side effects are less common than with the POP, as only very small amounts of hormone enter the bloodstream. The Mirena is larger than an IUD, so fitting may be difficult or painful in women who have never had children. Work is underway to develop a smaller device for this purpose.