The most important, though obvious, reason is to help us better understand sex-linked genetic defects in men after birth.

ECONOMIST: Genetics

Traditionally the most important civilizing role that women played was insisting that sex be linked to commitment and fatherhood.

FORBES: The Missing Elephant in the Bedroom

This means they are less prone to sex-linked genetic defects.

ECONOMIST: Genetics

The ultrasound and other technologies that identify the sex of a fetus started out as diagnostic devices to help people with sex-linked diseases, such as haemophilia, conceive healthy children.

ECONOMIST: Sex selection: Cat got your tongue? | The

If a well-rested, smarter and nonsmoking self is not enough, exercise has also been linked to a better sex life.

CNN: Exercise: Key to good sex, good sleep

The current combined pill, which contains progesterone and another female sex hormone oestrogen, has been linked to an increased risk of breast cancer.

BBC: NEWS | Health | Birth pill 'may cut cancer risk'