Couples who have difficulties conceiving can seek fertility treatment. At the same time, contraception is freely available to couples who want sex without producing a baby. Can this be right? As a society we value babies so much that we are prepared to allow - and fund - IVF. So how can we sanction - and fund - the deliberate prevention of babies being conceived? We can't have it both ways. Contraception should be banned.

Do you disagree with this? Perhaps, like most people, you believe that people should have control over their fertility. Couple X, who want a baby, benefit from fertility treatment. Couple Y, who do not want a baby, benefit from the availability of contraception. You see no contradiction in helping both couples. Enabling people to have wanted babies, you argue, is a completely separate matter from preventing unwanted pregnancies. You believe also that developments in fertility treatment should have no bearing on whether or not we allow people to use contraception.

You should therefore be baffled at the prevailing official view that the time limit for abortion should depend on the age at which premature babies can be saved. Some campaigners are calling for the abortion limit to be cut from 24 weeks to 20 weeks because an increasing proportion of babies born before 24 weeks' gestation can survive. Dawn Primarolo, the Health Minister, argues that survival rates for babies born at less than 24 weeks remain very poor, and therefore the abortion limit should be kept as it is. While she disagrees with the campaigners about the facts regarding the survival of premature babies, she has not questioned the notion that the abortion limit should be reduced when medical advances lead to a substantial improvement in the viability of premature babies.

This is nonsensical. The capacity of medicine to save a premature but much wanted baby is a completely separate matter from whether or not a woman should be permitted to abort a viable but unwanted pregnancy. In so far as ethics should determine a time limit on abortion, the relevant question is at what stage, if at all, a foetus should be regarded as a person, and in particular the extent to which it has a developed brain and can experience emotions. The state of incubator technology cannot answer that question, any more than progress in IVF technology should determine whether contraception should be permittted.

Advances in medicine normally lead to people having more choice. Linking the time limit on abortion to the age limit at which premature babies can be saved implies that medical progress should lead to less choice. This is perverse.

Dr Peter Sozou is a research Fellow at the London School of Economics

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