Women over the age of 40 still need to be vigilant when it comes to contraception, new research indicates.

Doctors in the US looked into this issue and found that women who enter their 40s often become less vigilant about contraception, believing that they will not become pregnant at that age.

Some also worry about the health effects of certain types of contraception, such as the oral contraceptive pill and intrauterine devices (IUD), such as the Mirena coil.

"Despite declining fertility, women over age 40 still require effective contraception if they want to avoid pregnancy. In addition, the benefits of birth control outweigh the risk. Even for women with risk factors, there are methods that can be safely used," explained Dr Rebecca Allen of the Women & Infants Hospital of Rhode Island.

She said that women need to discuss with their GP what type of contraception is best for them, as methods of birth control they used in the past may no longer be suitable, for example, if they have certain medical conditions.

Dr Allen also noted that some forms of contraception can offer relief from early symptoms of the menopause. For example, contraceptive pills that contain oestrogen can reduce the severity of hot flashes and night sweats.

The research was published in the Canadian Medical Association Journal.